Clinical Updates
23 October 2009
Pandemic (H1N1) 2009 influenza: Update 20: Current status of the pandemic
The World Health Organization (WHO) reports that as of 17 October 2009, nearly 415,000 confirmed cases of pandemic influenza (H1N1) 2009 have occurred, with nearly 5,000 deaths from 196 countries and territories [1]. As most countries have stopped counting individual cases, this represents a significant underestimate of the actual number of cases. The European Centre for Disease Prevention and Control (ECDC) produces a map of countries affected by pandemic influenza with the number of fatal cases per country [2].
In temperate countries of the northern hemisphere, rates of influenza-like activity (ILI) (fever and two or more of: cough, sore throat, runny nose, body aches, or headache) are generally increasing [1, 3]. Countries in North America are reporting ILI above baseline seasonal influenza rates. In Western Europe several countries, including the United Kingdom (UK), are reporting above baseline activity indicating an early start to the influenza season. There are also increases in ILI in Eastern Europe and Asia.
Tropical countries in the Americas and Asia are generally reporting lower activity. In temperate countries of the southern hemisphere, transmission has fallen below baseline rates of ILI. The 22 October 2009 issue (Volume 14, Issue 42) of Eurosurveillance is devoted to articles describing the pandemic in the southern hemisphere.
Pandemic (H1N1) 2009 influenza virus remains the predominant virus isolated in most regions [4]. China is an exception where nearly 50% of its isolates are seasonal influenza A (H3N2) which is co-circulating with pandemic virus. Pandemic viruses that are currently being isolated remain antigenically and genetically similar to the original isolate: A/California/7/2009, which is the virus used in pandemic vaccines.
Thirty-nine isolates have been found to be resistant to oseltamivir, each with the same mutation [4]. They remain sensitive to zanamivir, the other neuraminidase inhibitor. The finding of resistance has not changed recommendations for oseltamivir as the drug of choice for treatment and prophylaxis of pandemic influenza [5].
Several countries, including the UK, have begun vaccinating risk groups with pandemic (H1N1) 2009 influenza vaccine.
Clinical illness
Extensive experience with clinical cases of pandemic influenza has confirmed that most individuals experience an uncomplicated ILI with full recovery, even without anti-viral treatment. However, a small number of patients have severe illness with rapidly progressive pneumonia and respiratory failure [6]. Most of these patients have a primary viral pneumonia, but about a third of them have secondary bacterial infections, usually with Streptoccocus pneumoniae or Staphylococcus aureus. There is growing evidence that early treatment (usually within 48 hours) with oseltamivir or zanamivir improves the outcome. The groups at greatest risk of severe disease are pregnant women, children younger than two years, and persons with chronic medical conditions, particularly those with chronic lung disease including asthma [6-8]. Severe illness requiring intensive care does occur in persons without predisposing conditions.
Hajj travel
Hajj, the annual pilgrimage to Mecca, is scheduled to fall between the 25th and 29th of November 2009. This represents the largest gathering of Muslim pilgrims in the world. Guidance has been developed by the Ministry of Health of the Kingdom of Saudi Arabia for prevention of illness during the Hajj and includes recommendations for the prevention of influenza. The influenza guidelines are summarised in the NaTHNaC information sheet [9] and are:
- All Hajj pilgrims must receive vaccination against 2009-2010 seasonal influenza at least two weeks before applying for a visa. Proof of vaccination is required to obtain the visa, without exception.
- There will be screening of passengers on arrival at all ports into Saudi Arabia, and if persons are suspected to have pandemic influenza, they will be temporarily quarantined and admitted to hospital for further testing.
Pilgrims should check the NaTHNaC website and that of the Foreign and Commonwealth Office for any changes or updates to these recommendations. In addition, they should follow the other recommendations and requirements for the pilgrimage [9].
Advice for travellers
Travellers need to be aware that some countries have put into place health screening of arriving passengers [10, 11]. Travellers should check with their tour operator, and they can also consult the country pages of the Foreign and Commonwealth Office for specific information. Travellers should obtain travel insurance that covers trip cancellation and any potential disruptions to their trip, such as quarantine.
Those who are ill with an ILI should delay their travel, and seek medical advice. The Department of Health launched the National Pandemic Flu Service on 23 July 2009. Travellers can consult this service for guidance on managing an ILI, however, if they have serious underlying health conditions, are pregnant, or are calling about children under one year of age, they should contact their GP directly.
Travellers who fall in the clinical risk groups for seasonal influenza and pandemic (H1N1) 2009 influenza should receive vaccination prior to travel [12].
Further advice on the prevention of pandemic influenza during travel can be found on the NaTHNaC Health Information Sheet: Pandemic (H1N1) 2009 influenza: Advice for travellers.
Further information is available at the following sources
NaTHNaC Country Information pages: http://www.nathnac.org/ds/map_world.aspx
NaTHNaC Outbreak Surveillance Database: http://www.nathnac.org/countrysearch.aspx
Centers for Disease Control and Prevention, 2009 H1N1 Flu (Swine flu): http://www.cdc.gov/h1n1flu/
European Centre for Disease Prevention and Control. Pandemic (H1N1) 2009: http://ecdc.europa.eu/en/healthtopics/Pages/Influenza_A(H1N1)
Foreign and Commonwealth Office. Swine flu pandemic: http://www.fco.gov.uk/en/travelling-and-living-overseas/swine-flu
Health Protection Agency, Swine Influenza [Pandemic (H1N1) 2009 influenza]: http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAuto
ListName/Page/1240732817665?p=1240732817665
National Pandemic Flu Service: http://www.direct.gov.uk/pandemicflu
NHS Choices: http://www.nhs.uk/Pages/HomePage.aspx
WHO, Pandemic (H1N1) 2009: http://www.who.int/csr/disease/swineflu/en/index.html
References
1. World Health Organization. Pandemic (H1N1) 2009 - update 71. 23 October 2009. [Accessed 23 October 2009]. Available at: http://www.who.int/csr/don/2009_10_23/en/index.html
2. European Centre for Disease Control and Prevention. Reported cumulative number of confirmed cases of influenza A(H1N1)v and country reporting status by country, as of 22 October 2009, 16:00 hours CEST. [Accessed 23 October 2009]. Available at: http://ecdc.europa.eu/en/healthtopics/PublishingImages/World
3. Centers for Disease Control and Prevention. 2009 H1N1 Flu: Situation Update. 16 October 2009. [Accessed 23 October 2090]. Available at: http://www.cdc.gov/h1n1flu/update.htm
4. World Health Organisation. Pandemic (H1N1) 2009 – update 71. Weekly update (Virological surveillance data). 23 October 2009. [Accessed 23 October 2009]. Available at: http://www.who.int/csr/disease/swineflu/laboratory23_10_2009
5. World Health Organization. Antiviral drugs and pandemic (H1N1) 2009. 6 October 2009. [Accessed 23 October 2009]. Available at: http://www.who.int/csr/disease/swineflu/frequently_asked_
questions/swineflu_faq_antivirals/en/index.html
6. Clinical features of severe cases of pandemic influenza. Pandemic (H1N1) 2009 briefing note 13. 16 October 2009. [Accessed 23 October 32009]. Available at: http://www.who.int/csr/disease/swineflu/notes/h1n1_clinical
_features_20091016/en/index.html
7. Centers for Disease Control and Prevention. Recommendations for early empiric antiviral treatment in persons with suspected influenza who are at increased risk of developing severe disease. 19 October 2009.
8. Baker MG, Kelly H, Wilson N. Pandemic H1N1 influenza lessons from the southern hemisphere. Euro Surveill. 14(42):pii=19370, 2009. Available at: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19370
9. National Travel Health Network and Centre. Advice for pilgrims for the Hajj and Umrah season of 1430 (2009). September 2009. Available at: http://www.nathnac.org/pro/factsheets/Hajj_Umrah.htm
10. Centers for Disease Control and Prevention. Possible novel H1N1 flu screening for international travellers. 15 October 2009. [Accessed 23 October 2009]. Available at: http://wwwn.cdc.gov/travel/content/news-announcements/delays-H1N1-screening.aspx
11. NaTHNaC. Pandemic (H1N1) 2009 influenza: Update 16: Potential health screening of international travellers. 20 July 2009. Available at: http://www.nathnac.org/pro/clinical_updates/flu_200709.htm
12. Chief Medical Officer (CMO) letter. Department of Health. The H1N1 swine flu vaccination programme 2009-2010. 15 October 2009. [Accessed 23 October 2009]. Available at: http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets
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