12 June 2009

Swine influenza in humans: Update 13: The World Health Organization declares influenza pandemic

On 11 June 2009, the World Health Organization (WHO) raised the worldwide influenza pandemic alert level from phase 5 to phase 6 [1, 2]. This indicates that a global influenza pandemic is occurring; there is sustained community transmission of influenza A (H1N1)v virus (v = variant influenza virus) in several areas of the world. Although the pandemic alert is at level 6, this does not mean that illness with swine influenza has increased in severity. The WHO considers the current influenza pandemic to be of moderate severity, similar to seasonal influenza [3]. They encourage all countries to continue to monitor the outbreak, communicate information about it to the public, roll out sustainable plans for mitigating the health and social impact of influenza, and provide adequate medical care for those who are affected. 

Current status of the outbreak

As of 12 June 2009, the WHO reports nearly 30,000 cases [4]. Cases have been reported in 77 countries; see Table listing affected countries.

Most confirmed cases have been characterised by an uncomplicated febrile respiratory illness, with fever, cough, sore throat, malaise and headache [5]. However, gastrointestinal symptoms have been seen in up to a quarter of patients in the United States (US). Two to five percent of persons in the US and Canada have been hospitalised with severe illness characterised by pneumonia and respiratory failure; there has been a case fatality rate of 0.1 to 0.2 for these cases [5-7]. Many of those who have died have either been pregnant or had underlying conditions such as asthma or other chronic lung disease, diabetes, immunosuppression, and neurologic or cardiovascular disease. 

The predominant age group has been those under the age of 30 years [6]; the median age in the European Union is 23 years [8]. The younger age of cases may be related to exposure that has occurred during travel or in school settings. However, there is evidence that adults age 60 and older may have some pre-existing antibody to the swine influenza virus [9]. The complete implications of this finding are not known.

Advice for travellers

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

Before you travel

• If you are ill with a respiratory illness you should delay travel
• Check to see if your destination is reporting cases of swine flu. You can look on the NaTHNaC website for up-to-date case totals: http://www.nathnac.org/pro/swineflu.htm 
• You should consider:
• whether you need to go to a swine flu affected area
• the risk of getting swine flu at your destination
• the level of medical care at your destination including access to anti-viral medications in the event you need treatment for an influenza-like illness (ILI) (fever plus two or more of cough, sore throat, runny nose, muscle aches or headache).
• You should receive appropriate vaccines and other preventive measures for your destination. This includes seasonal influenza vaccine if you come under the recommended risk groups (see NaTHNaC Health Information Sheet on Influenza)
• You should obtain comprehensive travel health insurance, and clarify if there are any exclusions to coverage

During travel

Influenza is transmitted via the respiratory route and you should exercise sensible precautions:

• follow public health guidance at your destination
• avoid crowding or mass gatherings
• avoid close contact (within 2 meters) with persons who are ill with an ILI
• wash hands with soap and water; use waterless alcohol-based hand gels when soap and water is not available
• avoid touching your nose, mouth or eyes, to prevent the spread of germs
• cover your nose and mouth with a tissue when you cough or sneeze and dispose of the tissue promptly
• keep hard surfaces (e.g. door handles, countertops) clean using a normal cleaning solution
• assure that children follow similar advice
• swine flu is not passed through properly handled and prepared pork; the virus is killed by cooking to temperatures of 70°C
• there is little evidence of the effectiveness of wearing masks at a mass level, however, properly fitted, special grade masks can be worn in situations such as healthcare settings

After you travel

Travellers who have visited affected areas should monitor their health for seven days after the visit. If you develop a febrile illness with cough, sore throat, runny nose, headache or muscle aches, within seven days you should:

• check your symptoms on NHS Direct (www.nhsdirect.nhs.uk) or NHS Choices (www.nhs.uk), and if you remain concerned, contact your GP or NHS Direct (0845 4647) and inform them of your travel history
• limit contact with other people
• cover your nose and mouth with a tissue when you cough or sneeze and dispose of the tissue promptly
• wash hands with soap and water
• keep hard surfaces (e.g. door handles, countertops) clean using a normal cleaning solution
• There is guidance for health professionals who evaluate persons with suspected swine influenza on the Health Protection Agency website, listed below.

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: http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAuto

ListName/Page/1240732817665?p=1240732817665

Health Protection Agency: Algorithm for the management of suspected cases of swine influenza (A/H1N1v) (including returning travellers and visitors from countries affected by swine influenza A/H1N1v and contacts of known cases). S5a. 3 June 2009. [Accessed 12 June 2009]. Available at: http://www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1240732819

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WHO, Influenza A (H1N1): 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

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

The Lancet: H1N1 Flu Resource Centre: http://www.thelancet.com/H1N1-flu

References

1. World Health Organization. World now at the start of 2009 influenza pandemic. 11 June 2009. [Accessed 12 June 2009]. Available at: http://www.who.int/mediacentre/news/statements/2009/h1n1_p

andemic_phase6_20090611/en/index.html

2. World Health Organization. Current WHO phase of pandemic alert. [Accessed 12 June 2009]. Available at: http://www.who.int/csr/disease/avian_influenza/phase/en/index.

html

3. World Health Organization. What is phase 6? 11 June 2009. [Accessed 12 June 2009]. Available at: http://www.who.int/csr/disease/swineflu/frequently_asked_quest

ions/levels_pandemic_alert/en/index.html    

4. World Health Organization. Influenza A (H1N1) – update 48. 12 June 2009. [Accessed 12 June 2009]. Available at: http://www.who.int/csr/don/2009_06_12/en/index.html 

5. World Health Organization. Human infection with new influenza A (H1N1) virus: clinical observations from Mexico and other affected countries, May 2009. Wkly Epidem Rec 84:185-189, 2009. Available at: http://www.who.int/wer/2009/wer8421.pdf 

6. World Health Organization. Considerations for assessing the severity of an influenza pandemic. Wkly Epidem Rec 84:197-202, 2009. Available at: http://www.who.int/wer/2009/wer8422.pdf

7. Centers for Disease Control and Prevention. Hospitalized patients with novel influenza A (H1N1) virus infection – California, April-May, 2009. MMWR. 58:536-541, 2009. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5819a6.htm

8. ECDC working group on influenza A(H1N1)v. Preliminary analysis of influenza A (H1N1)v individual and aggregated case reports from EU and EFTA countries. Eurosurveillance 14(23). 11 June 2009. Available at: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=1923

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9. Centers for Disease Control and Prevention. Serum-cross-reactive antibody response to a novel influenza A (H1N1) virus after vaccination with seasonal influenza vaccine. MMWR 58:521-524. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5819a1.htm