10 July 2009

Pandemic (H1N1) 2009 influenza (swine influenza): Update 15: WHO recommends a change in reporting of pandemic influenza.

On 11 June 2009, the World Health Organization (WHO) declared an influenza pandemic [1]. This indicated that sustained human-to-human transmission of pandemic (H1N1) 2009 virus was occurring in at least one country of two or more WHO regions of the world. As of 7 July 2009, there were 137 countries, territories and areas reporting more than 98,000 cases with over 440 deaths [2, 3]. 

With widespread transmission of pandemic influenza, it has become increasingly difficult for many countries to identify every case and then confirm the diagnosis of influenza with laboratory testing. For countries with known cases of pandemic influenza, WHO now recommends that they move to using national indicators of disease such as monitoring for influenza-like illness and pneumonia [2]. The United Kingdom adopted this approach on 2 July 2009 [4]. It is still important to monitor for unusual events, such as clusters of cases, unusually severe disease, and symptoms that have not been reported previously.

Countries that have not reported cases should test persons suspected to have pandemic influenza so that the presence of the virus can be confirmed.

NaTHNaC will no longer provide a table of case totals for countries that have reported pandemic influenza. However, countries or territories that have newly reported cases, or in which one or more deaths have occurred will continue to be listed on the NaTHNaC Outbreak Surveillance Database.

Naming the pandemic virus

WHO have recommended that the name of the virus be changed to: pandemic (H1N1) 2009. This is to distinguish it from seasonal H1N1 influenza virus and to avoid the stigma of associating the name with swine.  NaTHNaC will adopt this terminology.

Oseltamivir resistant viruses

Three isolates of pandemic (H1N1) 2009 virus that are resistant to oseltamivir (Tamiflu®) have been identified [2, 5, 6]. The three viruses had the same mutation conferring resistance; they remained sensitive to zanamivir (Relenza®).

• On 29 June 2009, the National Influenza Centre in Denmark reported a resistant virus from a person who was taking oseltamivir chemoprophylaxis.
• On 2 July 2009, Japan reported a resistant virus from a person who was ill 15 May 2009, and who had been taking oseltamivir chemoprophylaxis.
• On 3 July 2009, the Hong Kong Department of Health reported a resistant virus from a person who had arrived from San Francisco and was ill on 11 June 2009. This person had not been taking antiviral medication.

These cases are considered rare, sporadic events. Therefore there are no changes in recommendations for the use of antiviral drugs for treatment or prevention of pandemic influenza.

Advice for travellers

There are no travel restrictions to any country. The current pandemic alert level is at phase 6, indicating widespread global transmission. Consistent with this, the WHO do not recommend closure of borders, nor do they recommend travel restrictions.

Please see the NaTHNaC Health Information Sheet: Pandemic (H1N1) 2009 influenza: Advice for travellers. 

Further information is available at the following sources:

Foreign and Commonwealth Office. Swine flu outbreak: http://www.fco.gov.uk/en/travelling-and-living-overseas/swine-flu

Health Protection Agency, Swine Influenza (influenza A H1N1v): http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAuto

ListName/Page/1240732817665?p=1240732817665

WHO, Pandemic (H1N1) 2009: http://www.who.int/csr/disease/swineflu/en/index.html

European Centre for Disease Prevention and Control: http://ecdc.europa.eu/

Centers for Disease Control and Prevention, H1N1 Flu (Swine flu): http://www.cdc.gov/h1n1flu/

NaTHNaC Country Information pages: http://www.nathnac.org/ds/map_world.aspx

NaTHNaC Outbreak Surveillance Database: http://www.nathnac.org/countrysearch.aspx

NHS Choices: http://www.nhs.uk/Pages/HomePage.aspx 

References

1. World Health Organization. World now at the start of 2009 influenza pandemic. 11 June 2009. [Accessed 26 June 2009]. Available at: http://www.who.int/mediacentre/news/statements/2009/h1n1_pa

ndemic_phase6_20090611/en/index.html

2. World Health Organization. Virtual press conference with Dr. Keith Fukuda. 7 July 2009. [Accessed 10 July 2009]. Available at: http://www.who.int/mediacentre/multimedia/swineflupressbriefin

gs/en/index.html

3. World Health Organization. Influenza A (H1N1) – update 54. 6 July 2009. [Accessed 10 July 2009]. Available at: http://www.who.int/csr/don/2009_07_06/en/index.html

4. Health Protection Agency. Treatment approach announced for pandemic flu. 2 July 2009. [Accessed 10 July 2009]. Available at: http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb

_C/1246519368102

5. World Health Organization. Pandemic (H1N1) 2009 news brief: no. 1. Viruses resistant to oseltamivir (Tamiflu) identified. 8 July 2009. [Accessed 10 July 2009]. Available at: http://www.who.int/csr/disease/swineflu/newsbriefs/h1n1_antivir

al_resistance_20090708/en/index.html

6. Centers for Disease Control and Prevention. CDC Health Advisory: Three reports of oseltamivir resistant novel influenza A (H1N1) viruses. 9 July 2009