Giuseppe
Emeritus
Public health measures taken at international borders during early stages of pandemic influenza A (H1N1) 2009: preliminary results (Wkly Epidemiol Rec., edited)
[Source: World Health Organization, Full PDF Document (LINK). Extract, edited.]
Weekly epidemiological record - Relev? ?pid?miologique hebdomadaire
21 may 2010, 85th year / 21 mai 2010, 85e ann?e - No. 21, 2010, 85, 185?196
http://www.who.int/wer
Public health measures taken at international borders during early stages of pandemic influenza A (H1N1) 2009: preliminary results
Background
Article 2 of the International Health Regulations (2005)(1) discourages unnecessary interference with international traffic and trade. Signatories to the regulations may consider applying health measures other than the relevant WHO recommendations and those defined in the regulations for points of entry, but careful appraisal of the potential impact and appropriateness of such measures should be made before implementation.
By March 2010, the pandemic influenza A (H1N1) 2009 virus had affected >200 countries and territories and claimed ≥17 483 lives among laboratory-confirmed cases alone.(2) As the outbreak emerged in April 2009, points of entry throughout the world became a focus of attention, and public health measures were rapidly implemented. In the early stages of the pandemic, particular efforts were made in many countries to prevent or at least delay and mitigate the crossborder spread of disease by applying intensified health screening and other safeguards to inbound and outbound travellers, as well as to modes of transport and cargo traffic. More than 170 countries are estimated to have implemented public health measures at points of entry, but the scope and methods of these measures, and their consequences on international traffic and trade, have not been elucidated except in reports and media reports.(3) This prompted the examination of, and an attempt to document, public health measures implemented at points of entry by authorities and the international travel industry during the first 3 months of the pandemic. The results of this survey will help countries adopt a consensus and evidence-based approach to implementing border measures to protect public health.
This report presents the preliminary results of an evaluation of public health measures taken at international points of entry in response to the pandemic (H1N1) 2009 virus from 20 April 2009 to 31 July 2009.
Methods
An informal advisory group was set up to formulate a multisectoral survey of public health measures applied at international borders to combat crossborder transmission of the emerging influenza virus. Collaborators included: WHO; subject-matter experts; the United States Centers for Disease Control and Prevention; the Hamburg Port Health Center (Germany); the International Civil Aviation Organization; and industry and trade associations including the Airports Council International (575 members operating >1633 airports in 179 countries and territories), the International Air Transport Association (230 airline members in 125 countries), the International Shipping Federation (32 national ship owners association members), and Cruise Lines International Association (25 cruise-line members representing >97% of the cruise capacity marketed in North America).
Four questionnaires were developed, each specifically tailored to a particular sector ? namely public health authorities (a full-length form with 31 questions and an excerpted form of 12 questions), the maritime industry (18 questions), airlines (13 questions), and airports (9 questions). Respondents, namely national focal points for the International Health Regulations (2005) or representatives of ship operators, airlines or airports, were prompted to document the control measures used from 20 April 2009 through 31 July 2009 and their impressions of the impact of the measures. Questionnaires were primarily distributed in English; a Spanish version of the questionnaire for national public health authorities was available to Spanish-speaking countries in the WHO Region of the Americas.
The questionnaires were designed to allow electronic reporting. They were disseminated by e-mail in early November 2009 through the WHO Regional Offices, airports, and the various industry and trade associations cited earlier; the deadline for responses was 27 November 2009. Preliminary results were presented at an informal consultation held by WHO during 9?11 December 2009. The meeting was attended by representatives of national public health authorities, academic institutions and industry partners, and provided an opportunity to discuss implementation of the International Health Regulations (2005) and public health measures at ports, airports and ground crossings in response to public health emergencies. To improve response rates, the deadline was extended to 15 February 2010, and reminders were sent.
Responses were compiled in a secure database maintained by WHO. Only de-identified and aggregated data were shared with the project?s partners for processing and further analysis. Descriptive analysis was performed separately for each sector because the questionnaires were not identical. Detection rates were calculated by country and aggregated for all reporting countries by dividing the number of cases detected by the number of passengers screened.
Definitions
For the purpose of this survey, the following definitions were used and provided in the questionnaires.
Results
A total of 144 responses were received: 56 from national public health authorities, representing 29% of WHO?s 193 Member States (17/56 responding health authorities [30%] completed the full-length form and 39/56 [70%] completed the excerpted form); 32 from airports; 25 from air operators; and 31 from shipping companies. Table 1 shows the geographical representation of responses by region and sector. This report focuses primarily on the survey of national public health authorities; results of the surveys of the aviation and maritime sectors will be presented later.
Altogether 91% (51/56) of countries reported providing pandemic-related health information to travellers. Information campaigns were initiated by 93% (43/46) by 8 May 2009; the distribution of these campaigns was similar across regions. Information was commonly provided by posters and handouts at points of entry, on official web sites and through news media. Other methods of distributing information included making announcements at points of entry and on-board aircraft, and using text messaging. Dissemination of information was actively conducted by the aviation industry and the maritime industry; and respondents from the travel industry generally felt that this dissemination was effective.
Twenty-six out of 56 responding countries (46%) recommended that their citizens avoid travelling to affected countries during the early stages of the pandemic; the median duration of travel advisories was 5 weeks, with some countries extending their recommendations beyond the study period. While no country mentioned cancelling flights or voyages to affected countries, the aviation and maritime industries reported cancellations, albeit rarely. Two countries (one each from the Region of the Americas and the European Region) reported denying entry to people from affected countries.
Six out of 56 countries (11%) reported restricting the entry of animals or goods from affected countries. Responses to questions about conveyance declarations of health and on-board inspections suggested a general trend towards intensifying requirements at the start of the pandemic; this occurred for all modes of transport (aircraft, ships and ground transport) (Table 2). Five out of 56 (9%) countries reported having denied free pratique to ≥1 mode of transport, mostly owing to the presence of ill people on-board; these responses corresponded to the experiences of a few ship operators and airlines whose vehicles were refused permission to embark or disembark passengers or crew due to illness or having visited affected countries prior to arrival.
Eighteen out of 56 (32%) countries reported having conducted routine entry screening of international travellers for communicable diseases prior to the pandemic; this number almost doubled to 34 (61%) during the early stages of the pandemic (20 April?31 July 2009).
The regional distribution of countries conducting screening during the survey period included 8/11 (73%) in the Americas, 8/25 (32%) in the European Region, 5/5 (100%) in the South-East Asia Region, and 13/15 (87%) in the Western Pacific Region. Altogether, 27/34 (79%) countries that conducted screening reported having done so at airports, of which 20/34 (74%) reported covering the majority of airports (76?100%); 18 (53%) screened at shipping ports and 15 (44%) screened at ground crossings.
Detailed results on primary health-screening methods were available from 17 countries that responded to the complete version of the form (10 in the Western Pacific Region, 3 in the European Region, 2 in the South-East Asia Region and 2 in the Region of the Americas). The use of travellers? health declarations increased from 9 countries (53%) prior to the pandemic to 13 (76%) between 20 April and 31 July 2009, although only 6 (46%) reported that all health declarations were reviewed.
The number of countries conducting visual inspection for signs of illness increased from 6 (35%) to 13 (76%), and temperature screening from 5 countries (29%) to 16 (94%). Of countries that reported screening passengers? temperatures, 14 (88%) used thermal scanners, 10 (63%) used thermometers and 5 (31%) used disposable temperature-measuring devices.
In some instances, passenger-locator cards were used to trace contacts of passengers arriving from affected areas instead of implementing systematic individual screening of passengers.
All 17 countries reported having performed secondary evaluations at points of entry using different combinations of temperature measurement, interviews and medical evaluations; influenza testing was conducted at points of entry by only 4 countries (24%). Reported fever thresholds ranged from 37.0 ?C to 38.5 ?C (median, 38.0 ?C).
Ten countries (6 in the Western Pacific, 2 in the Americas, 1 in South-East Asia, 1 in the European Region) reported screening between 5000 and 39 million passengers (median, 4.6 million) at airports during 20 April?30 July 2009. Four countries that screened a total of 1.8 million passengers (range, 5000 to 1.6 million; median 58 000) reported detecting confirmed cases of pandemic (H1N1) 2009 virus at rates ranging from 0.2/10 000 passengers screened to 2/10 000 screened, providing an aggregate detection rate of 1/10 000 screened. The other 6 countries, representing 50.6 million passengers screened (range, 5000 to 39 million; median, 1.2 million) did not detect any cases at airports. Thus, an aggregate total for the 10 countries may be calculated as 199 confirmed cases in >52 million passengers screened, providing a rate of approximately 4 cases/million passengers screened.
Fifteen out of 17 (88%) countries isolated suspected or confirmed cases; in 7 (47%) countries, criteria for isolation included symptoms of influenza-like illness; in 1 (7%) results from rapid influenza testing; in 8 (53%) confirmation of pandemic (H1N1) 2009 virus by polymerase chain reaction. Symptomatic travellers were isolated at hospitals, on-board ships, at designated quarantine facilities and at their homes. Ten out of 17 (59%) countries reported quarantining asymptomatic close contacts of cases for 3?10 days (median, 8 days).
Most countries defined close contacts on aircraft as someone sitting within 2?3 rows of the index case; 1 country included everyone on-board the airplane. For ships, 5/8 countries (63%) considered cabin-mates to be contacts; 2/8 (25%) included everyone on-board the ship. Home or hotel quarantine was reported most frequently (by 8 countries, or 80%), followed by on-board ship (5 countries, or 50%).
Travel delays attributed to entry screening were reported by only 3/17 (18%) countries, and were described as minimal (<1 hour); in contrast, surveys of the airline industry suggested that delays >30 minutes would be perceived as unacceptable.
Only 3/56 (5%) countries (2 in the Western Pacific Region and 1 in the European Region) reported conducting exit screening during the survey period both at airports and shipping ports; 2 countries conducted exit screening at ground crossings. Conversely, shipping companies reported conducting health screening for passengers or crew prior to embarkation. When exit screening was conducted, it took place at or before the check-in area.
A total of 14/20 (70%) countries reported that their strategies for combating pandemics by implementing border measures changed during the first few months of the pandemic as the disease became more prevalent in their communities.
Anecdotal information suggested that travel advisories and information provided to travellers prompted selfidentification of cases after arrival. Screening was also felt to have raised awareness among asymptomatic travellers.
Being prepared in advance of the pandemic and multisectoral cooperation was thought to have been crucial for the conduct of successful screening operations; however, screening was perceived to be resourceintensive and logistically challenging. A total of 9/16 (56%) countries stated that screening delayed entry of the pandemic virus into their communities; 7 respondents stated that there was no evidence that entry screening affected the course of the pandemic in their countries.
Discussion
During a global public health event, the potential for disrupting international travel and trade by implementing measures designed to control the introduction and spread of infectious diseases is high. In the early stages of the influenza A (H1N1) 2009 pandemic, there was heightened concern about international transmission of the disease with the result that public health authorities in many countries decided that it would be appropriate to take measures to prevent or delay introduction of the virus. The travel industry was challenged to respond to demands from public health authorities and the public.
The efficacy of health screening is difficult to evaluate, and data are not widely available in the literature, although a recent review of data from 35 countries suggested that entry screening could delay local transmission by 1?2 weeks.(4) Screening efficacy depends on a number of factors, including the intensity of resources applied to screening (in terms of the number of personnel, their training, and the technology used) and containment (isolation and quarantine), as well as previous experience and planning. The results of this survey suggest that confirmed cases may have been detected at an aggregate rate of 4/1 000 000 passengers screened in 10 countries. However, it is important to note that these numbers represent a limited number of countries, and the number of passengers screened by some countries was small. Furthermore, the detection rate for screening at ports of entry is influenced by a variety of factors, including the size and type of screening operations, the methods of data collection, timing during the phase of the epidemic curve, the incubation period and travelling time, and the level of exposure to suspected cases.
For instance, a report from China, where intensive screening was conducted, indicated that the overall detection rate at ports of entry until late August 2009 was roughly 14 cases/1 000 000 screened.(5) Therefore, the results of the surveys are not applicable to all countries that screened for pandemic (H1N1) 2009 virus, and the conclusions that can be drawn regarding the efficacy of screening are limited.
The results suggest that measures introduced at borders changed during the first 4 months of the pandemic, showing that countries adapted to changing epidemiology and recommendations. Early in the pandemic, a few countries instituted travel and trade restrictions, and almost half recommended avoiding travel to areas affected by the pandemic; however these restrictions and advisories were generally discontinued after a few weeks, suggesting that strategies shifted from a broad precautionary approach to more focused response measures implemented at points of entry. Control measures later shifted to communities as more information about the pandemic virus became available, perceptions of risk changed, and community transmission became more prevalent. The way strategies unfolded during the fast-changing pandemic was largely consistent with the approach taken by health authorities at European ports, where an emphasis was placed on building consensus among stakeholders. This suggests a need to establish an international network of public health partners to facilitate cross-sectoral communication regarding health issues at borders.(6)
The surveys used in this study were designed in collaboration with international experts in public health and the travel industry, and they provide the only global data obtained directly from officials involved in the public health response at points of entry and on international modes of transport. Responses to the 4 surveys represent a cross-section of public health responses initiated at borders, and include perceptions of the impact of public health measures on international travel and trade. However, the data are subject to several limitations.
Although 56 countries responded to the survey, only 17 answered the full-length form, thus limiting the availability of some data. Respondents did not represent all regions of the world; therefore results may not be generalizable to regions with low representation. The surveys focused on the first 4 months of the pandemic and therefore did not provide information on measures used, or changes made to strategies, as the pandemic progressed. The availability of the questionnaires only in English and Spanish might have presented a language barrier for some countries. No information is available on nonrespondents and the reasons for nonresponse, thus there may be a response bias. Because these limitations make it difficult to assess the generalizability of these findings, they should be explored in future investigations.
Conclusions
Acknowledgements
WHO would like to acknowledge the informal advisory group for this survey, particularly the Quarantine and Border Health Services Branch, Division of Global Migration and Quarantine at the United States Centers for Disease Control and Prevention, and the Hamburg Port Health Center, Germany, for their dedicated technical support throughout the work. WHO also thanks the Public Health Agency of Canada for providing access to data from the Global Public Health Intelligence Network.
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[Source: World Health Organization, Full PDF Document (LINK). Extract, edited.]
Weekly epidemiological record - Relev? ?pid?miologique hebdomadaire
21 may 2010, 85th year / 21 mai 2010, 85e ann?e - No. 21, 2010, 85, 185?196
http://www.who.int/wer
Public health measures taken at international borders during early stages of pandemic influenza A (H1N1) 2009: preliminary results
Background
Article 2 of the International Health Regulations (2005)(1) discourages unnecessary interference with international traffic and trade. Signatories to the regulations may consider applying health measures other than the relevant WHO recommendations and those defined in the regulations for points of entry, but careful appraisal of the potential impact and appropriateness of such measures should be made before implementation.
By March 2010, the pandemic influenza A (H1N1) 2009 virus had affected >200 countries and territories and claimed ≥17 483 lives among laboratory-confirmed cases alone.(2) As the outbreak emerged in April 2009, points of entry throughout the world became a focus of attention, and public health measures were rapidly implemented. In the early stages of the pandemic, particular efforts were made in many countries to prevent or at least delay and mitigate the crossborder spread of disease by applying intensified health screening and other safeguards to inbound and outbound travellers, as well as to modes of transport and cargo traffic. More than 170 countries are estimated to have implemented public health measures at points of entry, but the scope and methods of these measures, and their consequences on international traffic and trade, have not been elucidated except in reports and media reports.(3) This prompted the examination of, and an attempt to document, public health measures implemented at points of entry by authorities and the international travel industry during the first 3 months of the pandemic. The results of this survey will help countries adopt a consensus and evidence-based approach to implementing border measures to protect public health.
This report presents the preliminary results of an evaluation of public health measures taken at international points of entry in response to the pandemic (H1N1) 2009 virus from 20 April 2009 to 31 July 2009.
Methods
An informal advisory group was set up to formulate a multisectoral survey of public health measures applied at international borders to combat crossborder transmission of the emerging influenza virus. Collaborators included: WHO; subject-matter experts; the United States Centers for Disease Control and Prevention; the Hamburg Port Health Center (Germany); the International Civil Aviation Organization; and industry and trade associations including the Airports Council International (575 members operating >1633 airports in 179 countries and territories), the International Air Transport Association (230 airline members in 125 countries), the International Shipping Federation (32 national ship owners association members), and Cruise Lines International Association (25 cruise-line members representing >97% of the cruise capacity marketed in North America).
Four questionnaires were developed, each specifically tailored to a particular sector ? namely public health authorities (a full-length form with 31 questions and an excerpted form of 12 questions), the maritime industry (18 questions), airlines (13 questions), and airports (9 questions). Respondents, namely national focal points for the International Health Regulations (2005) or representatives of ship operators, airlines or airports, were prompted to document the control measures used from 20 April 2009 through 31 July 2009 and their impressions of the impact of the measures. Questionnaires were primarily distributed in English; a Spanish version of the questionnaire for national public health authorities was available to Spanish-speaking countries in the WHO Region of the Americas.
The questionnaires were designed to allow electronic reporting. They were disseminated by e-mail in early November 2009 through the WHO Regional Offices, airports, and the various industry and trade associations cited earlier; the deadline for responses was 27 November 2009. Preliminary results were presented at an informal consultation held by WHO during 9?11 December 2009. The meeting was attended by representatives of national public health authorities, academic institutions and industry partners, and provided an opportunity to discuss implementation of the International Health Regulations (2005) and public health measures at ports, airports and ground crossings in response to public health emergencies. To improve response rates, the deadline was extended to 15 February 2010, and reminders were sent.
Responses were compiled in a secure database maintained by WHO. Only de-identified and aggregated data were shared with the project?s partners for processing and further analysis. Descriptive analysis was performed separately for each sector because the questionnaires were not identical. Detection rates were calculated by country and aggregated for all reporting countries by dividing the number of cases detected by the number of passengers screened.
Definitions
For the purpose of this survey, the following definitions were used and provided in the questionnaires.
- Primary health screening: The first health-screening measures applied collectively to all people at points of entry.
- Secondary health evaluation: Further health evaluation implemented for people who tested positive during primary health screening.
- Visual inspection: Identification of people who appear sick or have signs of illness, such as a cough.
- Isolation: The separation of people who are ill or believed to be contagious in order to prevent the spread of infection or contamination.
- Quarantine: The separation from others of a person suspected of being exposed but who is not ill or symptomatic.
- Influenza-like illness: Illness with typical signs and symptoms of seasonal influenza including fever, cough, headache, body aches, sore throat, runny nose, and sometimes vomiting or diarrhoea.
- Free pratique: Permission for a ship to enter a port, to embark or disembark, to discharge or load cargo or stores; permission for an aircraft, after landing, to embark or disembark, to discharge or load cargo or stores; and permission for a ground transport vehicle, upon arrival, to embark or disembark, discharge or load cargo or stores.
Results
A total of 144 responses were received: 56 from national public health authorities, representing 29% of WHO?s 193 Member States (17/56 responding health authorities [30%] completed the full-length form and 39/56 [70%] completed the excerpted form); 32 from airports; 25 from air operators; and 31 from shipping companies. Table 1 shows the geographical representation of responses by region and sector. This report focuses primarily on the survey of national public health authorities; results of the surveys of the aviation and maritime sectors will be presented later.
Altogether 91% (51/56) of countries reported providing pandemic-related health information to travellers. Information campaigns were initiated by 93% (43/46) by 8 May 2009; the distribution of these campaigns was similar across regions. Information was commonly provided by posters and handouts at points of entry, on official web sites and through news media. Other methods of distributing information included making announcements at points of entry and on-board aircraft, and using text messaging. Dissemination of information was actively conducted by the aviation industry and the maritime industry; and respondents from the travel industry generally felt that this dissemination was effective.
Twenty-six out of 56 responding countries (46%) recommended that their citizens avoid travelling to affected countries during the early stages of the pandemic; the median duration of travel advisories was 5 weeks, with some countries extending their recommendations beyond the study period. While no country mentioned cancelling flights or voyages to affected countries, the aviation and maritime industries reported cancellations, albeit rarely. Two countries (one each from the Region of the Americas and the European Region) reported denying entry to people from affected countries.
Six out of 56 countries (11%) reported restricting the entry of animals or goods from affected countries. Responses to questions about conveyance declarations of health and on-board inspections suggested a general trend towards intensifying requirements at the start of the pandemic; this occurred for all modes of transport (aircraft, ships and ground transport) (Table 2). Five out of 56 (9%) countries reported having denied free pratique to ≥1 mode of transport, mostly owing to the presence of ill people on-board; these responses corresponded to the experiences of a few ship operators and airlines whose vehicles were refused permission to embark or disembark passengers or crew due to illness or having visited affected countries prior to arrival.
Eighteen out of 56 (32%) countries reported having conducted routine entry screening of international travellers for communicable diseases prior to the pandemic; this number almost doubled to 34 (61%) during the early stages of the pandemic (20 April?31 July 2009).
The regional distribution of countries conducting screening during the survey period included 8/11 (73%) in the Americas, 8/25 (32%) in the European Region, 5/5 (100%) in the South-East Asia Region, and 13/15 (87%) in the Western Pacific Region. Altogether, 27/34 (79%) countries that conducted screening reported having done so at airports, of which 20/34 (74%) reported covering the majority of airports (76?100%); 18 (53%) screened at shipping ports and 15 (44%) screened at ground crossings.
Detailed results on primary health-screening methods were available from 17 countries that responded to the complete version of the form (10 in the Western Pacific Region, 3 in the European Region, 2 in the South-East Asia Region and 2 in the Region of the Americas). The use of travellers? health declarations increased from 9 countries (53%) prior to the pandemic to 13 (76%) between 20 April and 31 July 2009, although only 6 (46%) reported that all health declarations were reviewed.
The number of countries conducting visual inspection for signs of illness increased from 6 (35%) to 13 (76%), and temperature screening from 5 countries (29%) to 16 (94%). Of countries that reported screening passengers? temperatures, 14 (88%) used thermal scanners, 10 (63%) used thermometers and 5 (31%) used disposable temperature-measuring devices.
In some instances, passenger-locator cards were used to trace contacts of passengers arriving from affected areas instead of implementing systematic individual screening of passengers.
All 17 countries reported having performed secondary evaluations at points of entry using different combinations of temperature measurement, interviews and medical evaluations; influenza testing was conducted at points of entry by only 4 countries (24%). Reported fever thresholds ranged from 37.0 ?C to 38.5 ?C (median, 38.0 ?C).
Ten countries (6 in the Western Pacific, 2 in the Americas, 1 in South-East Asia, 1 in the European Region) reported screening between 5000 and 39 million passengers (median, 4.6 million) at airports during 20 April?30 July 2009. Four countries that screened a total of 1.8 million passengers (range, 5000 to 1.6 million; median 58 000) reported detecting confirmed cases of pandemic (H1N1) 2009 virus at rates ranging from 0.2/10 000 passengers screened to 2/10 000 screened, providing an aggregate detection rate of 1/10 000 screened. The other 6 countries, representing 50.6 million passengers screened (range, 5000 to 39 million; median, 1.2 million) did not detect any cases at airports. Thus, an aggregate total for the 10 countries may be calculated as 199 confirmed cases in >52 million passengers screened, providing a rate of approximately 4 cases/million passengers screened.
Fifteen out of 17 (88%) countries isolated suspected or confirmed cases; in 7 (47%) countries, criteria for isolation included symptoms of influenza-like illness; in 1 (7%) results from rapid influenza testing; in 8 (53%) confirmation of pandemic (H1N1) 2009 virus by polymerase chain reaction. Symptomatic travellers were isolated at hospitals, on-board ships, at designated quarantine facilities and at their homes. Ten out of 17 (59%) countries reported quarantining asymptomatic close contacts of cases for 3?10 days (median, 8 days).
Most countries defined close contacts on aircraft as someone sitting within 2?3 rows of the index case; 1 country included everyone on-board the airplane. For ships, 5/8 countries (63%) considered cabin-mates to be contacts; 2/8 (25%) included everyone on-board the ship. Home or hotel quarantine was reported most frequently (by 8 countries, or 80%), followed by on-board ship (5 countries, or 50%).
Travel delays attributed to entry screening were reported by only 3/17 (18%) countries, and were described as minimal (<1 hour); in contrast, surveys of the airline industry suggested that delays >30 minutes would be perceived as unacceptable.
Only 3/56 (5%) countries (2 in the Western Pacific Region and 1 in the European Region) reported conducting exit screening during the survey period both at airports and shipping ports; 2 countries conducted exit screening at ground crossings. Conversely, shipping companies reported conducting health screening for passengers or crew prior to embarkation. When exit screening was conducted, it took place at or before the check-in area.
A total of 14/20 (70%) countries reported that their strategies for combating pandemics by implementing border measures changed during the first few months of the pandemic as the disease became more prevalent in their communities.
Anecdotal information suggested that travel advisories and information provided to travellers prompted selfidentification of cases after arrival. Screening was also felt to have raised awareness among asymptomatic travellers.
Being prepared in advance of the pandemic and multisectoral cooperation was thought to have been crucial for the conduct of successful screening operations; however, screening was perceived to be resourceintensive and logistically challenging. A total of 9/16 (56%) countries stated that screening delayed entry of the pandemic virus into their communities; 7 respondents stated that there was no evidence that entry screening affected the course of the pandemic in their countries.
Discussion
During a global public health event, the potential for disrupting international travel and trade by implementing measures designed to control the introduction and spread of infectious diseases is high. In the early stages of the influenza A (H1N1) 2009 pandemic, there was heightened concern about international transmission of the disease with the result that public health authorities in many countries decided that it would be appropriate to take measures to prevent or delay introduction of the virus. The travel industry was challenged to respond to demands from public health authorities and the public.
The efficacy of health screening is difficult to evaluate, and data are not widely available in the literature, although a recent review of data from 35 countries suggested that entry screening could delay local transmission by 1?2 weeks.(4) Screening efficacy depends on a number of factors, including the intensity of resources applied to screening (in terms of the number of personnel, their training, and the technology used) and containment (isolation and quarantine), as well as previous experience and planning. The results of this survey suggest that confirmed cases may have been detected at an aggregate rate of 4/1 000 000 passengers screened in 10 countries. However, it is important to note that these numbers represent a limited number of countries, and the number of passengers screened by some countries was small. Furthermore, the detection rate for screening at ports of entry is influenced by a variety of factors, including the size and type of screening operations, the methods of data collection, timing during the phase of the epidemic curve, the incubation period and travelling time, and the level of exposure to suspected cases.
For instance, a report from China, where intensive screening was conducted, indicated that the overall detection rate at ports of entry until late August 2009 was roughly 14 cases/1 000 000 screened.(5) Therefore, the results of the surveys are not applicable to all countries that screened for pandemic (H1N1) 2009 virus, and the conclusions that can be drawn regarding the efficacy of screening are limited.
The results suggest that measures introduced at borders changed during the first 4 months of the pandemic, showing that countries adapted to changing epidemiology and recommendations. Early in the pandemic, a few countries instituted travel and trade restrictions, and almost half recommended avoiding travel to areas affected by the pandemic; however these restrictions and advisories were generally discontinued after a few weeks, suggesting that strategies shifted from a broad precautionary approach to more focused response measures implemented at points of entry. Control measures later shifted to communities as more information about the pandemic virus became available, perceptions of risk changed, and community transmission became more prevalent. The way strategies unfolded during the fast-changing pandemic was largely consistent with the approach taken by health authorities at European ports, where an emphasis was placed on building consensus among stakeholders. This suggests a need to establish an international network of public health partners to facilitate cross-sectoral communication regarding health issues at borders.(6)
The surveys used in this study were designed in collaboration with international experts in public health and the travel industry, and they provide the only global data obtained directly from officials involved in the public health response at points of entry and on international modes of transport. Responses to the 4 surveys represent a cross-section of public health responses initiated at borders, and include perceptions of the impact of public health measures on international travel and trade. However, the data are subject to several limitations.
Although 56 countries responded to the survey, only 17 answered the full-length form, thus limiting the availability of some data. Respondents did not represent all regions of the world; therefore results may not be generalizable to regions with low representation. The surveys focused on the first 4 months of the pandemic and therefore did not provide information on measures used, or changes made to strategies, as the pandemic progressed. The availability of the questionnaires only in English and Spanish might have presented a language barrier for some countries. No information is available on nonrespondents and the reasons for nonresponse, thus there may be a response bias. Because these limitations make it difficult to assess the generalizability of these findings, they should be explored in future investigations.
Conclusions
- Design additional studies to specifically evaluate the efficacy of health measures implemented at borders to better guide planning for future public health emergencies. An open and collaborative study would facilitate the evaluation and enhance its accuracy and robustness.
- Conduct additional surveys to evaluate responses made at borders during later stages of the pandemic.
- Continue developing WHO guidance for contingency planning for responses to public health emergencies at points of entry according to scientific principles, best practices and evidence.(7, 8)
- Explore strategies to enhance communication about public health-related activities at ports, airports and ground crossings to facilitate international collaboration, the sharing of expertise and lessons learnt in a timely and consistent manner.
Acknowledgements
WHO would like to acknowledge the informal advisory group for this survey, particularly the Quarantine and Border Health Services Branch, Division of Global Migration and Quarantine at the United States Centers for Disease Control and Prevention, and the Hamburg Port Health Center, Germany, for their dedicated technical support throughout the work. WHO also thanks the Public Health Agency of Canada for providing access to data from the Global Public Health Intelligence Network.
- International Health Regulations (2005). Geneva, World Health Organization, 2005 (also available at LINK, accessed May 2010).
- Pandemic (H1N1) 2009 ? weekly update 94. WHO Geneva, World Health Organization, 2010 (LINK, accessed May 2010).
- Global Public Health Intelligence Network [online database]. Public Health Agency of Canada, 2010.
- Cowling BJ et al. Entry screening to delay local transmission of pandemic influenza A (H1N1). BMC Infectious Diseases, 2010, 10:82.
- Cao B et al. Clinical features of the initial cases of 2009 pandemic influenza A (H1N1) virus infection in China. New England Journal of Medicine, 2009, 361:2507?2517.
- The 2009 influenza A (H1N1) pandemic ? Difficulties and lessons learned by the European port health authorities. SHIPSAN Trainet Newsletter, 2010, 8:5?8 (also available at LINK).
- Responding to new influenza A(H1N1): options for interventions at international points of entry. Manila, World Health Organization Regional Office for the Western Pacific, 2009 (also available at LINK).
- Mouchtouri V et al. Preparedness for the prevention and control of influenza outbreaks on passenger ships in the EU: the SHIPSAN TRAINET project communication. Eurosurveillance, 2009, 14(21):1?4 (also available at LINK).
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