UKHSA detects human case of influenza A(H1N2)v (November 27, 2023) + Guidance, WHO rpt, links

[Pathfinder]

Press release


UKHSA detects human case of influenza A(H1N2)v


The UK Health Security Agency (UKHSA) has detected a single confirmed human case of influenza A(H1N2)v.

From: UK Health Security Agency

Published 27 November 2023

Influenza A(H1N2)v is similar to flu viruses currently circulating in pigs in the UK. This is the first detection of this strain of flu in a human in the UK.

As is usual early in emerging infection events, UKHSA is working closely with partners to determine the characteristics of the pathogen and assess the risk to human health.

The case was detected as part of routine national flu surveillance undertaken by UKHSA and the Royal College of General Practitioners (RCGP). The individual was tested by their GP after experiencing respiratory symptoms. Influenza A(H1N2)v virus was detected by UKHSA using polymerase chain reaction (PCR) testing and characterised using genome sequencing.

The individual concerned experienced a mild illness and has fully recovered. The source of their infection has not yet been ascertained and remains under investigation.

Close contacts of the case are being followed up by UKHSA and partner organisations. Any contacts will be offered testing as necessary and advised on any necessary further care if they have symptoms or test positive.

People with any respiratory symptoms should continue to follow the existing guidance; avoid contact with other people while symptoms persist, particularly if the people they are coming into contact with are elderly or have existing medical conditions.

UKHSA is monitoring the situation closely and is taking steps to increase surveillance within existing programmes involving GP surgeries and hospitals in parts of North Yorkshire. To assist in the detection of cases and assessment of transmission, those people who are contacted and asked to test are encouraged to do so.

Meera Chand, Incident Director at UKHSA, said:
It is thanks to routine flu surveillance and genome sequencing that we have been able to detect this virus. This is the first time we have detected this virus in humans in the UK, though it is very similar to viruses that have been detected in pigs.

We are working rapidly to trace close contacts and reduce any potential spread. In accordance with established protocols, investigations are underway to learn how the individual acquired the infection and to assess whether there are any further associated cases.
Chief Veterinary Officer, Christine Middlemiss, said:
We know that some diseases of animals can be transferred to humans – which is why high standards of animal health, welfare and biosecurity are so important.

Through our animal and human surveillance systems we work together to protect everyone. In this case we are providing specialist veterinary and scientific knowledge to support the UKHSA investigation. Pig keepers must also report any suspicion of swine flu in their herds to their local vet immediately.
Background on influenza viruses


Influenza A(H1) viruses are enzootic in swine populations in most regions of the world. When an influenza virus that normally circulates in swine is detected in a person, it is called a ‘variant influenza virus’.

H1N1, H1N2 and H3N2 are major subtypes of swine influenza A viruses in pigs and occasionally infect humans, usually after direct or indirect exposure to pigs or contaminated environments.

There have been a total of 50 human cases of influenza A(H1N2)v reported globally since 2005; none of them related genetically to this strain. Influenza A(H1N2)v has not previously been detected in humans in the UK. Human infections with swine influenza viruses occur sporadically.

Based on early information, the infection detected in the UK is a distinct clade (1b.1.1), which is different from recent human cases of influenza A(H1N2) elsewhere in the world but is similar to viruses in UK swine.

In 2009, there was a pandemic in humans caused by an influenza virus (influenza A H1N1(pdm09)) commonly referred to as ‘swine flu’. That virus contained genetic material from viruses that were circulating in pigs, birds and humans in the 1990s and 2000s.

Influenza A H1N1(pdm09) is now circulating in humans seasonally and is no longer referred to as swine flu. It is distinct from the viruses currently circulating in pigs.

...

https://www.gov.uk/government/news/ukhsa-detects-human-case-of-influenza-ah1n2v

[Michael Coston]

UKHSA Issues Guidance For Public On Possible H1N2v Exposure






#17,794

Five days ago the UKHSA Announced the 1st H1N2v (Swine Variant) Infection In the UK, in an individual who apparently tested positive in early November. The patient reportedly had mild illness and has recovered.

H1N2v is a swine variant influenza A virus that has been identified in other countries, including the United States, more than 4 dozen times over the past decade.

Normally swine variant viruses don't transmit well between humans, but some human-to-human transmission has been reported. This patient in the UK reportedly did not have direct or indirect contact with pigs, and their exposure had not been identified.

While no additional cases have been reported, today the UK's HSA has released detailed, and unusually stringent, guidelines for any one who has been notified that they have had contact with a ` . . . person who has or probably has influenza A(H1N2)v'

This guidance is divided into 3 parts, depending upon the category (High, Medium, Low) of exposure. The main announcement follows, after which I'll have some excerpts from the guidance for High Category Contacts, including self-isolation and home testing.

Guidance
Influenza A(H1N2)v: guidance for affected members of the public

Information for members of the public who have been affected by the detection of influenza A(H1N2)v in humans for the first time in the UK.

From:UK Health Security Agency Published 1 December 2023

Influenza A(H1N2)v: information for high category contacts

Influenza A(H1N2)v: information for medium category contacts

Influenza A(H1N2)v: information for low category contacts

Details

This guidance is for members of the public affected by influenza A(H1N2)v. You will have been told if this guidance applies to you.

It contains information about the disease and the actions that people should take if they have potentially been exposed to influenza A(H1N2)v. It also contains information about the disease and the actions that people should take if they potentially have an influenza A(H1N2)v infection. If this guidance is relevant to you, you will be told which piece of guidance applies to your situation.

Influenza A(H1N2) is a virus which normally infects pigs. Humans can be infected with this virus and the symptoms experienced are similar to human seasonal influenza (also called ‘flu’). The first human case of influenza A(H1N2)v in the UK was detected in November 2023. More information about what this means isprovided in a press releaseissued by the UK Health Security Agency (UKHSA).

The disease is usually mild to moderate and symptoms typically last for 3 to 5 days. More serious complications, such as pneumonia, are possible but rare.

It isn't clear from these documents what constitutes a High, Medium, or Low Category Contact, a determination that is apparently made by the UKHSA during contact tracing.

For High Category Contacts, they've announced some unusually rigorous guidelines (excerpts below), that far exceeds anything I've seen published for swine variant influenza exposure before.

Follow the links to read all of the documents in their entirety. Hopefully we'll learn more about their decision to publish these guidelines in the near future.

Guidance
Influenza A(H1N2)v: information for high category contacts

Published 1 December 2023

You have been given this information as you have been identified as someone who has had contact with a person who has or probably has influenza A(H1N2)v.

While you are at low risk of developing an infection, it can take up to 10 days for an infection to develop after you were exposed to influenza A(H1N2)v.

To help limit the spread of influenza A(H1N2)v and to protect others that you come into contact with, you should self-isolate until at least 10 days after you were last in contact with the person who has or probably has influenza A(H1N2)v. Your self-isolation period will end if you receive a negative test result for all of the nose and throat swabs you take during your isolation period, including the last swab which you will take on day 10.

You will have been given a designated contact number to phone. If you do not have this number, contact your local health protection team. Report any symptoms that develop to your designated contact up to 10 days following your last exposure.

(SNIP)

Actions to take

You should take the following actions to protect the health and safety of you, your family and anyone else that you may have contact with. These actions will reduce the spread of virus to others and ensure that if you develop the infection, it can be identified quickly.

As a precautionary measure, you should self-isolate at home for at least 10 days from when you were last exposed. This means you should stay at home and not go to work, school or public areas. You may end your self-isolation period if you receive a negative test result from the swab you will take on day 10 of your self-isolation period, and if all of your other test results have also been negative.

If you live on a farm with pigs, or keep these animals as pets, you should avoid any contact with them during your isolation period if you can.

If it is not possible to avoid contact with pigs, wear a face covering, and clean your hands with alcohol gel or soap and water before and after contact. Your face covering should cover your nose and mouth and fit well without gaps between the covering and your face.

Try to maintain distance from people living in the same household during your self-isolation period. If possible, stay in separate rooms from other household members.

If you use shared facilities, like the kitchen or bathroom, during your self-isolation period, avoid using them at the same time as other people and use a separate towel. Use them after everyone else, wear a face covering and clean surfaces after use. Your face covering should cover your nose and mouth and fit well without gaps between the covering and your face.

Clean surfaces in your home often. Pay particular attention to surfaces that are touched frequently, such as handles, light switches, work surfaces and electronic devices such as remote controls.

Maintain good ventilation of rooms by opening windows and leaving them open for at least 10 minutes after leaving rooms, particularly in shared rooms.

If you have to be in the same room as others during your self-isolation period, try to maintain good ventilation of the room, keep at least 2 metres away from others, and wear a face covering. Follow the advice given in the guidance on ventilation to reduce the spread of respiratory infections, including COVID-19.

Clean your hands regularly with alcohol gel or soap and water, especially before using shared rooms and after coughing, sneezing or blowing your nose.

Any non-essential medical or dental treatment should be postponed during your isolation period. You should discuss any essential treatment required with your designated contact before attending a healthcare facility.

Do not invite or allow social visitors, such as friends and family, to visit at home during your isolation period.

On days 1, 3, 5, 8 and 10 of your isolation period, use the nose and throat swab provided to you to test if you have developed an infection. If you were given the swabs later than 1 day after you were exposed, then use your first swab as soon as you receive it. Then continue with swabbing on correct days. For example, you may receive your swabs on day 4 and use the first one on day 4. You would then take your day 5, 8, and 10 swab as normal. You may only have received some of these swabs. In this case, you should use the swabs you have on the days instructed.

You may only end your isolation period if you receive a negative test result for all of the swabs you take during isolation period. This means you must wait until you receive the result of your day 10 test before you know whether you can end isolation.

Inform your designated contact point daily of any of the symptoms listed below within 10 days of your last exposure.

During your self-isolation period, you may be offered medication to help prevent an infection or to reduce the severity of your symptoms if you were to become ill.

You may be asked to take blood tests to help understand and control the spread of influenza A(H1N2)v.

Stay tuned.

https://afludiary.blogspot.com/2023/12/ukhsa-issues-guidance-for-public-on.html

[Michael Coston]

WHO DON Update On H1N2v Virus Infection in the UK






#17,795

On the heels of the UK's release of Guidance for the Public in the event they are identified as having had contact with a possible H1N2v case, we have the WHO DON (Disease Outbreak News) report on the UK's first case.

Thus far we've seen no indication of additional cases, although contract tracing is apparently still ongoing.

The link and some excerpts from the WHO update follow. Click the link to read it in its entirety.

Influenza A(H1N2) variant virus infection - United Kingdom of Great Britain and Northern Ireland
1 December 2023

Situation at a Glance

On 25 November 2023, the International Health Regulations National Focal Point (IHR NFP) of the United Kingdom of Great Britain and Northern Ireland (United Kingdom) notified the World Health Organization (WHO) of a human case of swine-origin influenza A(H1N2) virus infection. This is the first swine influenza A(H1N2)v case reported in the United Kingdom.

Human infections with swine-origin influenza viruses have been sporadically detected in the past in countries in the Americas, Asia, Australia and Europe. When a human is infected with a swine-origin influenza virus, the virus is referred to as a variant (or “v”) virus. Most human cases result from exposure to swine influenza viruses through direct contact with infected swine or contaminated environments. Current evidence suggests that these swine-origin influenza viruses have limited ability for sustained transmission among humans.

This case was identified as part of routine surveillance of respiratory illnesses. The source of infection for this case is under investigation and contact tracing is in process. To date, no other confirmed cases associated with this event have been reported. WHO is in communication with national authorities to monitor the situation closely. Ongoing investigations are in place to identify the source of the infection and to characterize the risks of this influenza variant virus. WHO assesses the risk of spread of swine-origin influenza viruses through humans and/or community-level spread among humans as low.

However, because these viruses continue to be detected in swine populations worldwide, further human cases following direct or indirect contact with infected swine can be expected. Current evidence suggests that these viruses have not acquired the ability to sustain transmission among humans. Due to the constantly evolving nature of influenza viruses, WHO continues to stress the importance of global surveillance to detect virological, epidemiological and clinical changes associated with circulating influenza viruses that may affect human (or animal) health and timely virus sharing for risk assessment.

Description of the Situation

On 25 November 2023, under the IHR (2005), the United Kingdom notified the WHO of a human case of influenza A(H1N2)v virus infection. The case reported onset of mild symptoms on 5 November. He visited his general practitioner on 9 November; during this visit, a respiratory sample was collected and further analyzed as part of the national routine influenza surveillance programme. On 13 November, the sample was sent to United Kingdom Health Security Agency (UKHSA) laboratories and tested positive on 23 November for influenza A(H1N2)v virus, using reverse transcription polymerase chain reaction (RT-PCR). The sample was further characterized by whole genome sequencing and results were available on the same date. On 25 November, a follow-up RT-PCR test was performed and tested negative for influenza. The case is now fully recovered.

Further laboratory analyses conducted at the Worldwide Influenza Centre at the Francis Crick Institute (a WHO Collaborating Centre) and the World Organization for Animal Health (WOAH) avian and swine influenza reference laboratory at the Animal and Plant Health Agency, indicated that this influenza A(H1N2)v virus belongs to the swine influenza virus genetic clade 1B.1.1. Similar A(H1N2) viruses from this genetic clade have been previously detected in pigs in the United Kingdom. However, this is the first time a virus from this swine genetic clade has been detected in a human in the United Kingdom.

According to ongoing investigations, pig farms are located within a few miles of where the case resides; however, the case reported no direct exposure to pigs, pets, or farms. The source of infection is currently under investigation and contact tracing is continuing.

(SNIP)

WHO Risk Assessment

Influenza viruses circulate in swine populations in many regions of the world. Depending on geographic location, the genetic characteristics of these viruses differ. Most human cases result from exposure to swine influenza viruses through contact with infected swine or contaminated environments, although some cases have been reported without an apparent source of exposure to swine in the weeks prior to illness onset. Because these viruses continue to be detected in swine populations worldwide, further human cases following direct or indirect contact with infected swine can be expected.

Current evidence suggests that these viruses have not acquired the ability to sustain transmission among humans. There has been limited, non-sustained human-to-human transmission of variant influenza viruses, although ongoing community transmission has not been identified.

This is the first swine influenza A(H1N2)v case reported in the United Kingdom. There is no clear indication of direct contact with pigs or any ill individuals. Though the source of infection is unknown at this time, the virus is closely aligned to that circulating in the swine population in the United Kingdom. Several previous variant cases have also not had clear exposure histories to swine and there was no evidence of sustained human-to-human transmission in these cases. Limited human-to-human transmission may have played a role, but there is no definitive evidence.

Further virus characterization is ongoing. National routine surveillance indicators do not show any unusual increases in respiratory illness in the local population. The risk of there being additional human cases associated with this event appears to be low – though the possibility of limited person-to-person transmission cannot be excluded at this stage.

The risk assessment will be reviewed should further epidemiological or virological information become available.

(Continue . . . )


,,

https://afludiary.blogspot.com/2023/12/who-don-update-on-h1n2v-virus-infection.html

[sharon sanders]

Please see:

Michigan Reports Two Influenza Swine Variant Infections (H3 & H1N2) - WHO & CDC Updates - August 2023

Taiwan reports 3rd human H1N2v swine flu infection - May 2023

US - CDC FluView Reports Another Novel Swine Variant (H1N2v) Infection - September 2022

US - Michigan: MI: H1N2v case in a Berrier Co. fairgoer - September 2022

US - CDC Confirms Another Human Infection with Flu Virus from Pigs in Oregon (H1N2v) - August 2022

CDC Confirms Another Human Infection with Flu Virus from Pigs in Oregon (H1N2v) - August 2022

US - CIDRAP NEWS SCAN: Omicron variant severity; Variant H1N2 flu in California; Deadly infant formula outbreak; Malawi wild poliovirus case; More H5 avian flu in US waterfowl - February 2022

Virol J . Human infection with a reassortant swine-origin influenza A(H1N2)v virus in Taiwan, 2021

US - Seasonal Flu 2009+, including H1N1 pandemic 2009

Europe -Seasonal Flu 2009+ including H1N1 pandemic 2009

China and related areas for the H1N1 pandemic 2009 - Please see this page of the seasonal flu forum and click on the "Next" button located at the bottom right corner for the previous time period: https://flutrackers.com/forum/forum/...racking/page27

[Michael Coston]

UKHSA Publishes Update & Risk Assessment On H1N2v



#18,011

Two weeks ago the UKHSA Announced the 1st H1N2v (Swine Variant) Infection In the UK, in an individual who apparently tested positive in early November. The patient reportedly had mild illness and has recovered, but their source of infection was unknown.

H1N2v is a swine variant influenza A virus that has been identified in other countries, including the United States, more than 4 dozen times over the past decade.

Eleven days ago (Dec 1st) we saw the UKHSA release unusually stringent Guidance For Public On Possible H1N2v Exposure, and the WHO released their DON (Disease Outbreak News) summary on the lone identified case.

As we've discussed often, detection of sporadic novel flu infections in the general population is often a matter of luck, even in countries with robust surveillance and reporting capabilities.

Last March, in UK Novel Flu Surveillance: Quantifying TTD, the UKHSA estimated their Time To Detection (TTD) could require 3-10 weeks, and the infection of dozens (or even hundreds) of people, before community spread could be established.

And this is for the UK. The TTD in many less-developed regions would presumably take longer.

Today the UKHSA has released a brief update and a more lengthy technical report/risk assessment, indicating that no additional cases have been identified, but that enhanced surveillance will continue for the next few weeks.

UKHSA publishes update on influenza A(H1N2)v

No further cases of influenza A(H1N2)v have been found. Enhanced surveillance will continue over the coming weeks.

From:UK Health Security Agency Published11 December 2023

The UK Health Security Agency (UKHSA) has published its investigation findings on the recent case of influenza A(H1N2)v.

The case was detected as part of routine national flu surveillance undertaken by UKHSA and the Royal College of General Practitioners (RCGP).

The virus was identified by UKHSA on 23 November using genome sequencing, the first time a human case of this particular virus has been confirmed in the UK.

Rapid work has been underway to learn more about the virus and its characteristics, including how it may have been acquired and whether it may have spread.

There remains only one human case of influenza A(H1N2)v in England. The case was an otherwise well person over 75 years of age, who has recovered fully.

Although the virus is similar to those detected in pigs in England and the case lives in a region containing pig farms, no direct contact between the case and any animal was reported.

No further cases have been detected through investigations, including follow-up of contacts to date and enhanced surveillance through local GP practices and hospital trusts.

Enhanced surveillance will continue over the coming weeks as a precaution.

UKHSA Incident Director Dr Meera Chand said:

This is the first time we have detected this virus in humans in the UK. Since the virus was confirmed we have been working rapidly to learn more about it and how it might have been acquired.

Investigations to date have not identified any further human cases and sporadic cases of influenza from swine viruses are known to occur.

The identification of this case highlights the importance of our flu surveillance and genomic sequencing in helping us to identify and learn more about new viruses.

UK Health Security Agency press office

10 South Colonnade
London
E14 4PU

Email ukhsa-pressoffice@ukhsa.gov.uk

The a link, and some excerpts from the full report follow:

Influenza A(H1N2)v: rapid technical assessment

Published 11 December 2023

Situation update

A human case of influenza A (H1N2)v clade 1B.1.1 was detected in England through routine community respiratory virus surveillance. The case is an otherwise well person over 75 years of age, who recovered fully. Although the virus was similar to those detected in pigs in England and the case lives in a region of England containing pig farms, no direct contact between the index case and any animal was reported.

UKHSA with APHA and Defra, the Francis Crick Institute, local NHS partners and the local authority therefore investigated:

1. To determine the source of infection, backwards contact tracing and assessment of potential locations for animal to human spillover in the vicinity of the case were undertaken. Although the case lives in an area of the country which contains pig farms and in proximity to sites containing animals (including a veterinary facility and a live auction market) no direct link or chain of transmission could be identified between the case and any animal. Environmental sampling is ongoing.

2. To identify any potential human to human transmission: contact tracing, polymerase chain reaction (PCR) testing and serology are being used. One household contact and one other contact were symptomatic but their symptoms had already resolved by the time they were identified, and therefore they were not tested whilst unwell. At the time of testing, one of these contacts had a non-influenza respiratory pathogen detected although its significance is unclear given timing with respect to symptoms. To date, no further cases have been detected through the investigations including follow-up of contacts (including precautionary follow up of the contacts of symptomatic contacts). Serological assessment is ongoing.

3. To rule out any local community transmission, enhanced surveillance is being conducted (community and hospital). Following the index case, no further cases have been detected to date through enhanced surveillance through local GP practices (Table 1) and hospital trusts, but this will continue for a further 4 weeks.

Exploratory studies have also been initiated to improve knowledge of spillover risk and to develop capability for future events, including an assessment of the potential of wastewater testing, environmental studies of potential spillover locations, and protocols for surveillance of occupational groups with relevant animal exposure. Work is also ongoing to assess the ability of currently available diagnostic assays to detect this strain.

This report provides a summary of the assessment that UKHSA makes for novel or emerging influenza viruses. Data used for the assessment was provided by UKHSA, APHA, and the Worldwide Influenza Centre at the Francis Crick Institute.

(SNIP)

Human to human transmission

There is no virologically confirmed human-to-human transmission. The human case viral genome is closely related to circulating viruses in pigs (‘moderate confidence’) and the mutational profile where it can be interpreted is consistent with a hypothesis of recent emergence (‘low confidence’).

The presence of a case without direct contact with animals, and the presence of a symptomatic household contact, mean that some limited degree of human-to-human transmission may have occurred (‘low confidence’).

No onwards transmission has been detected through PCR testing of contacts (‘low confidence’; given the normal surveillance lag time in identifying the influenza variant, most testing was relatively late compared to potential exposure and serological assessment is in process and may change this assessment).

No other cases have been detected through UKHSA enhanced community surveillance, including amongst 133 acute respiratory illness patients swabbed between 1 October and 1 December at the nearest 5 RCGP sentinel practices. This is the first ever detection of a non-human influenza strain through RCGP surveillance.

Influenza A(H1N2) sporadic human cases have been detected internationally, usually with direct links to swine, although these are not within the same specific clade.

Severity of disease

No conclusions can be drawn from a single case.
Antigenic characteristics

Based on rapid assessments undertaken by Worldwide Influenza Centre (WIC, FCI), currently available H1 subtype 1B lineage candidate vaccine viruses (CVVs) for prepandemic preparedness, would be unlikely to afford protection against the H1 1B.1.1 swine influenza A viruses detected in the UK.

Additionally, based on a small panel of UK sera taken pre- and post- vaccination with the 2023 to 2024 influenza vaccine, the current seasonal influenza vaccine will likely not afford protection against the H1 1B.1.1 swine influenza A viruses detected in the UK. Further assessment is underway.

(Continue . . . )

While a swine variant virus like H1N2v would likely have a far less severe impact compared to an avian flu like H5N1, it wouldn't necessarily be as mild as the 2009 H1N1 pandemic.

Hopefully this case was a one-off, dead-end infection.

But the swine source for these viruses remains, and future spillovers into humans - in the UK, and elsewhere in the world - may have more `legs'.

https://afludiary.blogspot.com/2023/12/ukhsa-publishes-update-risk-assessment.html