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Source : http://www.hpa.org.uk/webw/HPAweb&HP...=1231252394302
KEY POINTS
The rates of flu-like illness and related activity have started to increase in England. The increase was mainly seen in school age children.
Hospitalisations of people with suspected pandemic flu in England have levelled overall. The majority of cases continue to be mild.
Two samples from UK patients have been shown to have the genetic change associated with oseltamivir resistance. Both were from immunocompromised patients. One has been shown to be resistant, the other is undergoing further tests to confirm resistance. Globally over 10,000 specimens have been tested and 23 have been shown to be resistant to oseltamivir.
Interpretation of data to produce estimates on the number of new cases continues to be subject to a considerable amount of uncertainty. HPA modelling gives an estimate of 5,000 new cases in England last week (range 3,000 to 11,000).
This estimate incorporates data from National Pandemic Flu Service and GP consultations.
VIRAL CHARACTERISTICS
The Health Protection Agency has reported to the World Health Organization (WHO) the identification in the UK of a pandemic H1N1 2009 flu virus resistant to the antiviral oseltamivir (Tamilflu®
.
The resistant virus was identified in an immuno-compromised patient. The virus has a genetic change, H274Y in the N1 gene and is resistant to oseltamivir but retains susceptibility to the antiviral zanamivir (Relenza®.
Preliminary test results have also shown that a second virus (in a separate immuno-compromised patient) has the genetic change. We will be able to confirm if this virus is resistant at the end of the week.
There is no evidence of onward transmission of the resistant viruses.
This is not an unexpected development. If the second sample is confirmed, then these two samples are among a small number of resistant pandemic H1N1 2009 flu viruses to have already been identified worldwide through enhanced surveillance during the current pandemic. To date the manufacturers of oseltamivir (Roche) have reported 23 cases globally. Based on current information, these isolates appear to be sporadic and at this time there is no evidence of widespread antiviral resistance among pandemic H1N1 2009 flu viruses.
Testing carried out by the HPA indicates that both patients were initially infected with oseltamivir-susceptible virus, with resistance to the drug developing during their treatment. The emergence of antiviral drug resistant flu viruses during treatment has been reported in the past and its link to immuno-compromised patients is well established.
In a healthy individual the body's immune system would ordinarily effectively eliminate any virus. However, with immuno-compromised individuals, their immune response is affected and they continue to shed flu virus for prolonged periods.
The one, possibly two, UK cases were identified through testing carried out on flu virus samples received at the Agency's Centre for Infections. We are confident that these surveillance measures will enable us to identify any further resistant isolates.
To date (as of 16 September 2009) 913 viruses have been analysed by the Centre for Infections for the genetic marker commonly associated with resistance to oseltamivir in seasonal H1N1 flu (H274Y). These are the only two viruses found to carry this marker in the UK. In addition, 253 specimens have been fully tested for susceptibility; all, apart from one, were found to be sensitive to both oseltamivir and zanamivir.
The Agency is continually assessing its advice to government on health protection policies such as antiviral use. Currently there is no requirement to change existing guidance.
SEVERITY
Disease severity continues to be monitored. The disease is generally mild in most people so far, but is proving severe in a small minority of cases.
Swine flu hospitalisations in England: 143 patients (currently hospitalised as of 8am on 16 September).
Deaths - the number of deaths related to swine flu in England is 67 (This figure represents the number of deaths in individuals with swine flu but does not represent the number of deaths that can be attributed to swine flu).
KEY POINTS
The rates of flu-like illness and related activity have started to increase in England. The increase was mainly seen in school age children.
Hospitalisations of people with suspected pandemic flu in England have levelled overall. The majority of cases continue to be mild.
Two samples from UK patients have been shown to have the genetic change associated with oseltamivir resistance. Both were from immunocompromised patients. One has been shown to be resistant, the other is undergoing further tests to confirm resistance. Globally over 10,000 specimens have been tested and 23 have been shown to be resistant to oseltamivir.
Interpretation of data to produce estimates on the number of new cases continues to be subject to a considerable amount of uncertainty. HPA modelling gives an estimate of 5,000 new cases in England last week (range 3,000 to 11,000).
This estimate incorporates data from National Pandemic Flu Service and GP consultations.
VIRAL CHARACTERISTICS
The Health Protection Agency has reported to the World Health Organization (WHO) the identification in the UK of a pandemic H1N1 2009 flu virus resistant to the antiviral oseltamivir (Tamilflu®
.The resistant virus was identified in an immuno-compromised patient. The virus has a genetic change, H274Y in the N1 gene and is resistant to oseltamivir but retains susceptibility to the antiviral zanamivir (Relenza®
.Preliminary test results have also shown that a second virus (in a separate immuno-compromised patient) has the genetic change. We will be able to confirm if this virus is resistant at the end of the week.
There is no evidence of onward transmission of the resistant viruses.
This is not an unexpected development. If the second sample is confirmed, then these two samples are among a small number of resistant pandemic H1N1 2009 flu viruses to have already been identified worldwide through enhanced surveillance during the current pandemic. To date the manufacturers of oseltamivir (Roche) have reported 23 cases globally. Based on current information, these isolates appear to be sporadic and at this time there is no evidence of widespread antiviral resistance among pandemic H1N1 2009 flu viruses.
Testing carried out by the HPA indicates that both patients were initially infected with oseltamivir-susceptible virus, with resistance to the drug developing during their treatment. The emergence of antiviral drug resistant flu viruses during treatment has been reported in the past and its link to immuno-compromised patients is well established.
In a healthy individual the body's immune system would ordinarily effectively eliminate any virus. However, with immuno-compromised individuals, their immune response is affected and they continue to shed flu virus for prolonged periods.
The one, possibly two, UK cases were identified through testing carried out on flu virus samples received at the Agency's Centre for Infections. We are confident that these surveillance measures will enable us to identify any further resistant isolates.
To date (as of 16 September 2009) 913 viruses have been analysed by the Centre for Infections for the genetic marker commonly associated with resistance to oseltamivir in seasonal H1N1 flu (H274Y). These are the only two viruses found to carry this marker in the UK. In addition, 253 specimens have been fully tested for susceptibility; all, apart from one, were found to be sensitive to both oseltamivir and zanamivir.
The Agency is continually assessing its advice to government on health protection policies such as antiviral use. Currently there is no requirement to change existing guidance.
SEVERITY
Disease severity continues to be monitored. The disease is generally mild in most people so far, but is proving severe in a small minority of cases.
Swine flu hospitalisations in England: 143 patients (currently hospitalised as of 8am on 16 September).
Deaths - the number of deaths related to swine flu in England is 67 (This figure represents the number of deaths in individuals with swine flu but does not represent the number of deaths that can be attributed to swine flu).