WHO: Pandemic (H1N1) 2009 – update 63

Pandemic (H1N1) 2009 – update 63

Weekly update

In the southern hemisphere, most countries (represented by Chile, Argentina, New Zealand, and Australia) appear to have passed their peak of influenza activity and have either returned to baseline levels or are experiencing focal activity in later affected areas; while a few others (represented by South Africa and Bolivia) continue to experience high levels of influenza activity.
Many countries in tropical regions (represented by Central America and tropical regions of Asia), continue to see increasing or sustained high levels of influenza activity with some countries reporting moderate strains on the healthcare system. In temperate areas of the northern hemisphere (represented by North America, Europe, and Central Asia), influenza and respiratory disease activity remains low overall, with some countries experiencing localized outbreaks. In Japan, the level of influenza activity has passed the seasonal epidemic threshold, signaling a very early beginning to the annual influenza season.
Pandemic H1N1 influenza virus continues to be the predominant circulating strain of influenza, both in the northern and southern hemisphere. Antiviral susceptibility testing has increased in several countries, confirming that pandemic H1N1 influenza virus remains sensitive to the antiviral oseltamivir, except for sporadic reports of oseltamivir resistant pandemic H1N1 virus detailed in the previous web update (No. 62).


WHO: Pandemic (H1N1) 2009 briefing note 9

Pandemic (H1N1) 2009 briefing note 9

Preparing for the second wave: lessons from current outbreaks

28 AUGUST 2009 | GENEVA –

Monitoring of outbreaks from different parts of the world provides sufficient information to make some tentative conclusions about how the influenza pandemic might evolve in the coming months.

WHO is advising countries in the northern hemisphere to prepare for a second wave of pandemic spread. Countries with tropical climates, where the pandemic virus arrived later than elsewhere, also need to prepare for an increasing number of cases.

Countries in temperate parts of the southern hemisphere should remain vigilant. As experience has shown, localized “hot spots” of increasing transmission can continue to occur even when the pandemic has peaked at the national level.

H1N1 now the dominant virus strain

Evidence from multiple outbreak sites demonstrates that the H1N1 pandemic virus has rapidly established itself and is now the dominant influenza strain in most parts of the world. The pandemic will persist in the coming months as the virus continues to move through susceptible populations.

Close monitoring of viruses by a WHO network of laboratories shows that viruses from all outbreaks remain virtually identical. Studies have detected no signs that the virus has mutated to a more virulent or lethal form.

Likewise, the clinical picture of pandemic influenza is largely consistent across all countries. The overwhelming majority of patients continue to experience mild illness. Although the virus can cause very severe and fatal illness, also in young and healthy people, the number of such cases remains small.

Large populations susceptible to infection

While these trends are encouraging, large numbers of people in all countries remain susceptible to infection. Even if the current pattern of usually mild illness continues, the impact of the pandemic during the second wave could worsen as larger numbers of people become infected.

Larger numbers of severely ill patients requiring intensive care are likely to be the most urgent burden on health services, creating pressures that could overwhelm intensive care units and possibly disrupt the provision of care for other diseases.

Monitoring for drug resistance

At present, only a handful of pandemic viruses resistant to oseltamivir have been detected worldwide, despite the administration of many millions of treatment courses of antiviral drugs. All of these cases have been extensively investigated, and no instances of onward transmission of drug-resistant virus have been documented to date. Intense monitoring continues, also through the WHO network of laboratories.

Not the same as seasonal influenza

Current evidence points to some important differences between patterns of illness reported during the pandemic and those seen during seasonal epidemics of influenza.

The age groups affected by the pandemic are generally younger. This is true for those most frequently infected, and especially so for those experiencing severe or fatal illness.

To date, most severe cases and deaths have occurred in adults under the age of 50 years, with deaths in the elderly comparatively rare. This age distribution is in stark contrast with seasonal influenza, where around 90% of severe and fatal cases occur in people 65 years of age or older.

Severe respiratory failure

Perhaps most significantly, clinicians from around the world are reporting a very severe form of disease, also in young and otherwise healthy people, which is rarely seen during seasonal influenza infections. In these patients, the virus directly infects the lung, causing severe respiratory failure. Saving these lives depends on highly specialized and demanding care in intensive care units, usually with long and costly stays.

During the winter season in the southern hemisphere, several countries have viewed the need for intensive care as the greatest burden on health services. Some cities in these countries report that nearly 15 percent of hospitalized cases have required intensive care.

Preparedness measures need to anticipate this increased demand on intensive care units, which could be overwhelmed by a sudden surge in the number of severe cases.

Vulnerable groups

An increased risk during pregnancy is now consistently well-documented across countries. This risk takes on added significance for a virus, like this one, that preferentially infects younger people.

Data continue to show that certain medical conditions increase the risk of severe and fatal illness. These include respiratory disease, notably asthma, cardiovascular disease, diabetes and immunosuppression.

When anticipating the impact of the pandemic as more people become infected, health officials need to be aware that many of these predisposing conditions have become much more widespread in recent decades, thus increasing the pool of vulnerable people.

Obesity, which is frequently present in severe and fatal cases, is now a global epidemic. WHO estimates that, worldwide, more than 230 million people suffer from asthma, and more than 220 million people have diabetes.

Moreover, conditions such as asthma and diabetes are not usually considered killer diseases, especially in children and young adults. Young deaths from such conditions, precipitated by infection with the H1N1 virus, can be another dimension of the pandemic’s impact.

Higher risk of hospitalization and death

Several early studies show a higher risk of hospitalization and death among certain subgroups, including minority groups and indigenous populations. In some studies, the risk in these groups is four to five times higher than in the general population.

Although the reasons are not fully understood, possible explanations include lower standards of living and poor overall health status, including a high prevalence of conditions such as asthma, diabetes and hypertension.

Implications for the developing world

Such findings are likely to have growing relevance as the pandemic gains ground in the developing world, where many millions of people live under deprived conditions and have multiple health problems, with little access to basic health care.

As much current data about the pandemic come from wealthy and middle-income countries, the situation in developing countries will need to be very closely watched. The same virus that causes manageable disruption in affluent countries could have a devastating impact in many parts of the developing world.

Co-infection with HIV

The 2009 influenza pandemic is the first to occur since the emergence of HIV/AIDS. Early data from two countries suggest that people co-infected with H1N1 and HIV are not at increased risk of severe or fatal illness, provided these patients are receiving antiretroviral therapy. In most of these patients, illness caused by H1N1 has been mild, with full recovery.

If these preliminary findings are confirmed, this will be reassuring news for countries where infection with HIV is prevalent and treatment coverage with antiretroviral drugs is good.

On current estimates, around 33 million people are living with HIV/AIDS worldwide. Of these, WHO estimates that around 4 million were receiving antiretroviral therapy at the end of 2008.


Britain and France receive first batches of H1N1 vaccine

The Associated Press reported that Britain and France received their first batches of swine flu vaccine “as governments begin to arm themselves against a widely expected second wave of the pandemic in the northern winter.” British and French health officials said the H1N1 vaccine should win licensing approval for distribution in their countries by October. Britain’s Department of Health said it received a first batch of 100,000 doses of swine flu vaccine from Baxter. France “has reserved 94 million doses of vaccine from four pharmaceutical companies and expects to have several million doses by mid-October when the vaccines are set to win market approval.


FDA issues EUA for H1N1 influenza virus test for troops overseas

The FDA announced that it issued an Emergency Use Authorization (EUA) that allows a 2009 H1N1 influenza virus test to be used to detect the virus in troops serving overseas. The EUA “allows the U.S. Department of Defense to distribute the H1N1 test to its qualified laboratories that have the required equipment and trained personnel to perform the test and interpret its results. An EUA authorizes the use of unapproved medical products or unapproved uses of approved medical products during a declared public health emergency.” FDA Commissioner of Food and Drugs Margaret A. Hamburg, M.D. commented, “The FDA worked quickly with the Defense Department to authorize the use of this test to better protect our troops. The test will aid in more rapid diagnosis of 2009 H1N1 influenza infections so that deployed troops can quickly begin appropriate medical treatment.” http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm180153.htm

MMWR: ACIP Recommendations on H1N1 Vaccines

The MMWR: August 28, 2009 / Vol. 58 / No. RR–10 includes:
2009 Pandemic Influenza A (H1N1) Virus Infections
Chicago, April–July 2009

On April 21, 2009, CDC reported the first cases of 2009 pandemic influenza A (H1N1) virus infection in the United States. On April 24, in response to those reports, the Chicago Department of Public Health established enhanced surveillance for 2009 pandemic influenza A (H1N1) virus infections. The first cases were identified on April 28. This report summarizes laboratory confirmed cases identified during April 24–July 25, and provides clinical and epidemiologic data for a subset of those cases

Use of Influenza A (H1N1) 2009 Monovalent Vaccine
Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2009
This report provides recommendations by CDC’s Advisory Committee on Immunization Practices (ACIP) regarding the use of vaccine against infection with novel influenza A (H1N1) virus. Licensed vaccine is expected to be available by mid-October 2009. Highlights of these recommendations include 1) the identification of five general population target groups for initial focus of vaccination efforts (pregnant women, persons who live with or provide care for infants aged <6 months, health-care and emergency medical services personnel, children and young adults aged 6 months–24 years, and persons aged 25–64 years who have medical conditions that put them at higher risk for influenza-related complications), 2) establishment of a priority for a subset of persons within the initial target groups in the event that initial vaccine availability is unable to meet demand, and 3) guidance on use of vaccine in other adult population groups as vaccine availability increases.


WHO: two doses of measles vaccine as standard for all national programmes

The WHO issued its revised position paper on measles vaccination making “vaccination of all children with two doses of measles vaccine as the standard for all national immunization programmes.” WHO said the second dose can be administered through routine services or given periodically through mass vaccination campaigns to defined age groups. In 2007, WHO estimated that 82% of the world’s children received one dose of measles vaccine by their first birthday and about 197,000 people, mostly children under the age of five, died from measles. “To eliminate measles, countries need to reach at least 95% nationwide coverage with two doses of measles vaccine. To achieve reduction of measles mortality, vaccination coverage should reach at least 90% at the national level and 80% in each district,” WHO said.

WHO position paper on measles vaccine [pdf 724kb]

Gates Foundation names Dr. Stefano Bertozzi as HIV director

The Bill & Melinda Gates Foundation’s Global Health Program announced that Dr. Stefano Bertozzi will join as HIV director effective 31 August 2009. Dr. Bertozzi “will lead a team that manages the foundation’s portfolio of grants in HIV vaccine development, biomedical prevention research, diagnostics, development and resistance monitoring, and strategies for introduction and scaling-up of the foundation, said, “Stefano brings a wealth of experience to his new role. His intimate knowledge of the medicine, science, economics and policy of HIV will help make this important portfolio have the most impact.” Gates said that Dr. Bertozzi worked with the foundation in his previous roles at UNAIDS, the World Health Organization (WHO) and the World Bank. For the last 11 years, he has been with the National Institute of Public Health (INSP) in Mexico. http://www.gatesfoundation.org/press-releases/Pages/dr-stefano-bertozzi-leading-hiv-vaccine-team-090826.aspx