Emergencies preparedness, response

Pandemic (H1N1) 2009 - update 75

Weekly update

As of 15 November 2009, worldwide more than 206 countries and overseas territories or communities have reported laboratory confirmed cases of pandemic influenza H1N1 2009, including over 6770 deaths.

As many countries have stopped counting individual cases, particularly of milder illness, the case count is likely to be significantly lower than the actual number of cases that have occurred. WHO is actively monitoring the progress of the pandemic through frequent consultations with the WHO Regional Offices and member states and through monitoring of multiple sources of data.

Situation update:

The situation remains similar since the last update. In temperate regions* of the northern hemisphere, the early arriving winter influenza season continues to intensify across parts of North America and much of Europe. However, there are early signs of a peak in disease activity in some areas of the northern hemisphere.

In the United States, influenza transmission remains active and geographically widespread, although disease activity appears to have recently peaked in most areas except in the northeastern United States. In Canada, influenza transmission continues to intensify without a clear peak in activity; the ILI consultation rate, which has been highest among children aged 5-19, continues to significantly exceed mean rates observed over the past 12 influenza seasons.

In Europe, widespread and increasing transmission of pandemic influenza virus was observed across much of the continent but the most intense circulation of virus occurred in northern, eastern, and southeastern Europe. Transmission appears to have peaked in few countries of Western Europe including Iceland, Ireland, the UK (Northern Ireland), and Belgium after a period of sustained intense transmission. Further east, a number of countries reported sharp increases in the rates of ILI** (Serbia, Moldova, Norway, Lithuania, Georgia) or ARI (Belarus, Bulgaria, Romania, and Ukraine). A moderate or greater impact on the healthcare system was reported in parts of northern and southeastern Europe. Greater than 20% of all sentinel respiratory specimens tested positive for influenza in at least 20 countries, with ≥ 50% of samples testing positive for influenza in Spain, Portugal, Estonia, Slovenia, Slovakia, Moldova, Bosnia and Herzegovina, Greece, Norway, Finland, Denmark, Belgium, Iceland, and Ireland. Over 99% of subtyped influenza A viruses in the Europe were pandemic H1N1 2009.

In Central and Western Asia, increasing diseases activity and pandemic influenza virus isolations continues to be reported in several countries. A high intensity of respiratory diseases with increasing trend was reported in Kazakhstan. Recent increases in rates of ILI or ARI have been observed in Uzbekistan and in parts of Afghanistan (particularly in the capital region and in southern and northeastern provinces). In Israel, sharp increases in rates of ILI and pandemic virus detections have been reported in recent weeks.

In East Asia, influenza transmission remains active. Intense influenza activity continues to be observed in Mongolia with a severe impact on the healthcare system; however, disease activity may have recently peaked in the past 1-2 weeks. In Japan, influenza activity remains elevated but stable nationally, and may be decreasing slightly in populated urban areas. A small number of seasonal H3N2 and H1N1 influenza viruses continue to be detected in China and South East Asia, though the proportion of seasonal viruses is declining in relation to the proportion of pandemic influenza H1N1.

In tropical zone of the Americas and Asia, the intensity of influenza transmission is variable. In the tropical areas of Central and South America, most countries continue to report declining influenza activity, with the exception of Peru and Colombia. In the Caribbean Epidemiology Centre (CAREC) countries, after a recent peak of disease activity, rates of ARI have declined over the past 3-4 weeks. With the exception of Sri Lanka, overall transmission continues to decline in most parts of tropical South and Southeast Asia. In Hong Kong SAR, rates of ILI have returned baseline after a recent wave of predominantly pandemic H1N1 influenza in September and October.

In the temperate region of the southern hemisphere, little pandemic influenza activity has been reported.

For more epidemiologic information please refer to the recent Weekly Epidemiological Report on Transmission Dynamics and Impact of Pandemic Influenza A (H1N1) 2009 Virus.

WHO estimates that around 80 million doses of pandemic vaccine have been distributed and around 65 million people have been vaccinated. Campaigns are using a variety of different vaccines. Although intense monitoring of vaccine safety continues, all data compiled to date indicate that pandemic vaccines match the excellent safety profile of seasonal influenza vaccines.

*Countries in temperate regions are defined as those north of the Tropic of Cancer or south of the Tropic of Capricorn, while countries in tropical regions are defined as those between these two latitudes.

Qualitative indicators (Week 29 to Week 45: 13 July - 8 November 2009)

The qualitative indicators monitor: the global geographic spread of influenza, trends in acute respiratory diseases, the intensity of respiratory disease activity, and the impact of the pandemic on health-care services.

The maps below display information on the qualitative indicators reported. Information is available for approximately 60 countries each week. Implementation of this monitoring system is ongoing and completeness of reporting is expected to increase over time.

Geographic spread of influenza activity
Trend of respiratory diseases activity compared to the previous week
Intensity of acute respiratory diseases in the population
Impact on health care services
Laboratory-confirmed cases of pandemic (H1N1) 2009 as officially reported to WHO by States Parties to the IHR (2005) as of 15 November 2009

The countries and overseas territories/communities that have newly reported their first pandemic (H1N1) 2009 confirmed cases since the last web update (No.74): none.

The countries and overseas territories/communities that have newly reported their first deaths among pandemic (H1N1) 2009 confirmed cases since the last web update (No 74): Sri Lanka, Pakistan and Slovenia.

*Given that countries are no longer required to test and report individual cases, the number of cases reported actually understates the real number of cases. **The total number of cases are no longer reported from these regions