Tuesday, June 15, 2010

Pandemic (H1N1) 2009 - update 104

WHO's Weekly update

11 June 2010 -- As of 6 June, worldwide more than 214 countries and overseas territories or communities have reported laboratory confirmed cases of pandemic influenza H1N1 2009, including over 18156 deaths.

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 information.

Situation update:
Active but declining transmission of pandemic influenza virus persists in limited areas of the tropics, particularly in Southeast Asia and the Caribbean. As countries of the temperate southern hemisphere enter winter, only sporadic influenza activity has been detected so far, except in Chile and Uruguay, both of which have recently reported small numbers of pandemic influenza virus detections. Although seasonal influenza B viruses have been the predominant type of influenza virus circulating worldwide since the end of February 2010, there have been increasing but low level detections of seasonal influenza H3N2 viruses, particularly in South America and in East Africa.

In the tropics of the Americas, overall pandemic influenza activity is low, however, both seasonal influenza H3N2 and type B viruses are actively circulating in parts of tropical South America. Active but declining transmission of pandemic influenza virus continues to be detected primarily in Cuba. Since early 2010, pandemic influenza virus has circulated at low levels in Costa Rica. Sporadic detections of pandemic influenza virus continue to be reported in Brazil. During the most recent reporting week (last week of May 2010), both Brazil and Venezuela reported regional spread of influenza activity associated with an increasing trend of respiratory diseases. In Venezuela, recent influenza activity (which began during early May 2010) has been predominantly due to circulating seasonal influenza A viruses. In Bolivia, circulation of seasonal influenza viruses, predominantly type B, was observed between March and May 2010 and now appears to be subsiding.

In Asia overall pandemic influenza virus transmission remains low, except in parts of tropical South and Southeast Asia, particularly Singapore, Malaysia, and Bangladesh. In Singapore, overall levels of ARI remained slightly below the epidemic threshold and the proportion of respiratory samples testing positive for pandemic influenza virus increased slightly to 34%. In Malaysia, limited data suggests that pandemic influenza virus transmission has begun to decline since plateauing during May 2010. In Bangladesh, there has been stable persistent low level co-circulation of pandemic and seasonal influenza B viruses since March 2010. Sporadic detections of pandemic influenza virus continued to be reported across other parts of Asia. In East Asia, overall influenza activity remains low, however, seasonal influenza B viruses continue to circulate at low and declining levels.

In Sub-Saharan Africa, pandemic influenza virus continued to circulate at low levels in parts of West Africa, most notably in Ghana. During the most recent reporting week, 13% of all respiratory samples tested positive for pandemic influenza virus in Ghana. Small but significant numbers of seasonal H3N2 viruses have been detected in Kenya and Tanzania since late May 2010.

Overall, in the temperate regions of the northern hemisphere, pandemic influenza viruses have been detected only sporadically during the past month. In the temperate southern hemisphere, only two countries, Chile and Uruguay, have recently reported small numbers of pandemic influenza virus detections. In Chile, there was low level geographically limited circulation of pandemic influenza virus during May 2010; 3.4% of respiratory samples tested positive for pandemic influenza virus during the last week of May 2010. Of note, in Uruguay, 11 (44%) of 25 samples tested positive for pandemic influenza during the most recent reporting week (the last week of May 2010); however, the corresponding intensity of respiratory diseases in the population is not yet known. Other respiratory viruses, most notably RSV, are known to be circulating in Chile and Argentina. There have been no recent detections of pandemic influenza virus in South Africa. In New Zealand and Australia, overall levels of ILI remain low; only sporadic detections of seasonal and pandemic influenza viruses have been recently reported in Australia.

Source: http://www.who.int/csr/don/2010_06_11/en/index.html

WHO defends pandemic actions, says rules need tightening

Jun 10, 2010 (CIDRAP News) – The World Health Organization (WHO) replied at greater length today to recent criticism of the way it used science advisors in pandemic planning, defending its response to the H1N1 flu pandemic but allowing that its policies concerning transparency and relations with the pharmaceutical industry need strengthening.

Today's WHO statement largely reiterates points made by WHO Director-General Margaret Chan in a Jun 8 letter, but it offers more details and goes a step further by expressing regret that the agency did not list the industry connections of WHO advisors who helped develop pandemic guidance published in 2004 on the use of vaccines and antivirals.

The new statement was issued in response to an article and editorial published Jun 3 in BMJ (formerly the British Medical Journal) and a report by a committee of the Parliamentary Assembly of the Council of Europe (PACE), a human rights organization. The reports and editorial raised questions about possible conflicts of interest among the WHO's pandemic advisors because they had done paid work for pharmaceutical companies. The PACE committee report went further, branding the WHO's pandemic response an "unjustified scare" that led to wasteful spending.

Concerning potential conflicts of interest, the WHO notes that many leading experts who advise the agency have ties with industry, such as research funding, consulting work, and participation in industry-sponsored conferences. To guard against biased advice, the WHO requires expert advisors to declare their interests, and it assesses those interests to decide if any action is required, the statement says.

It adds, "The publication of summaries of relevant interests following meetings is inconsistent and needs to be made routine. WHO further acknowledges that safeguards surrounding engagement with industry need to be tightened, and is doing so."

The BMJ critique focused heavily on the 2004 pandemic guidance, stating that the industry connections of three scientists who helped write the guidance were not listed in the document. The guidance was based on a meeting held in 2002.

"In line with WHO policy, all experts who participated in this meeting were required to submit a declaration of interest form and all such forms were duly reviewed by WHO," today's statement says. "However, a summary of relevant interests was not issued together with the publication. WHO regrets this oversight.

"Since that time, a number of administrative and legal changes have been implemented to strengthen procedures for addressing potential conflicts of interest that might influence the advice provided to WHO. WHO is committed to tightening these procedures further and ensuring their more consistent application."

The BMJ critique also dwelt on the WHO's withholding of the names of members of the Emergency Committee it established last year to advise on its response to the pandemic. The article implied that the panel members may have conflicts of interest that slant their advice.

The WHO has said it has withheld the names to protect the members from commercial or political pressures. Today's statement provides more background on this rationale.

Whether to release the names was debated when the committee was set up under the International Health Regulations, the WHO said. The names of members of other advisory groups are released after their meetings. However, the SARS (severe acute respiratory syndrome) epidemic in 2003 showed that public health emergencies can cause considerable economic and social disruption, suggesting that "experts could well be lobbied or pressured for commercial or political reasons."

After considering the issues, the WHO decided to follow its usual practice of disclosing the names of experts after completion of the advisory group's work. But the committee has held a number of meetings over more than a year, rather than a single meeting like most advisory groups, so the release of names has been delayed.

The names of members and summaries of their declarations of interest will be issued after the pandemic is declared over, the WHO said. Meanwhile, "Procedures for revealing names of member of future Emergency Committees are under review."

Other points in today's statement, which is presented in a question-and-answer format, deal more with the substance of the WHO's pandemic guidance and decisions.

For example, the statement summarizes how the H1N1 virus differed from seasonal flu and met the criteria for a pandemic: it was genetically unique, it circulated in summer, it hit younger people, it crowded out other flu viruses, and antibodies to seasonal H1N1 flu did not protect people.

The WHO rejects the critics' assertion that it removed severity from its definition of a pandemic. In particular, it addresses a 2003 WHO document—often cited by critics—stating that a flu pandemic causes "enormous numbers of deaths and illnesses."

"At the time, this was considered a likely scenario should the highly lethal H5N1 avian influenza virus develop an ability to spread readily among humans, but it was never a formal definition," the statement says.

The WHO also repeated Chan's flat rejection of the allegation that it declared a pandemic to boost the earnings of drug companies, saying no evidence for this has been found.

The statement also defends the agency's guidance on use of antivirals during the pandemic.

Source: http://www.cidrap.umn.edu/cidrap/content/influenza/swineflu/news/jun1010who.html

Study raises questions about age-group impact of H1N1

Jun 14, 2010 (CIDRAP News) – A study by French researchers suggests that the H1N1 influenza pandemic may not have differed from seasonal influenza epidemics in its effects on different age-groups quite so much as has been supposed.

The general understanding is that H1N1 has disproportionately affected children and young adults, leaving elderly people relatively unscathed. The new study agrees that the younger groups have borne a much larger share of pandemic deaths than they do in seasonal flu, but it suggests that the age distribution of total cases is much the same as in past seasonal flu epidemics.

"The age distribution of influenza-like illness was similar between the 2009 H1N1 pandemic and seasonal epidemics whereas the proportion of under-60s among influenza deaths was markedly higher during the 2009 pandemic (peak<20 years) than during the seasonal epidemics," says the report by Magall Lamaitre and Fabrice Carrat. It was published online last week by BMC Infectious Diseases.

The US Centers for Disease Control and Prevention (CDC) has estimated that about 90% of all pandemic H1N1 cases were in people younger than 65 and that 32% were in children (under 18). The BMC study implies that this disproportionate burden of illness in young people is not much different from what happens in seasonal flu.

The French researchers compared the age distribution of cases and deaths during two different seasonal flu epidemics in the United States and France with the age distribution of pandemic H1N1 cases and deaths in the two countries.

For the seasonal epidemics, the researchers chose the H1N1 epidemics of 1978-79 in the United States and 1998-89 in France and the H3N2 epidemics of 1989-90 in both countries.

They used influenza-like illness (ILI) as the indicator of cases (morbidity), gathering data from published studies, the CDC, and France's Sentinel flu surveillance system. The age distributions of flu-related deaths were obtained from national death registries.

To assess the relative burden of illness and deaths on different age-groups, the investigators calculated a relative illness ratio (RIR) and a relative mortality ratio (RMR). The RIR is the percentage of sick people in a given age-group divided by the percentage of the total population belonging to that age-group. Similarly, the RMR is the percentage of total flu deaths in a given age-group divided by the percentage of total all-cause deaths in that age-group. Any ratio greater than 1 signals a disproportionate burden.

Overall, the age profile of the 2009 pandemic resembled that of the seasonal epidemics, the researchers found. The highest illness burdens (RIR values) in the pandemic were in 5- to 9-year-olds in France (RIR, 2.97) and in 0- to 4-year-olds in the United States (RIR, 3.49).

The 5- to 9-year-old group had the highest illness burdens in both seasonal epidemics in France (H1N1, 2.15; H3N2, 1.77). In the US seasonal epidemics, the highest illness ratio in the 1978-79 H1N1 outbreak fell on 10- to 14-year-olds (2.99) and, in the 1989-90 H3N2 epidemic, on 5- to 24-year-olds (1.84). All the RIRs for those 35 and older were lower than 1.

In contrast to the morbidity pattern, the age pattern for deaths differed sharply between the pandemic and the seasonal epidemics, the researchers found. In the pandemic, RMRs for those under 60 were all higher than 1, with peak ratios in those under age 20. In the United States the hardest hit age-group was 5- to 24-year-olds (RMR, 38.66), while 5- to 9-year-olds were hardest hit in France (RMR, 37.39).

In three of the four seasonal epidemics, the highest RMRs were in those 65 and older, the report says. The exception was the 1978-79 H1N1 epidemic in the United States, in which the 5- to-24-year-old age-group had the highest relative mortality (RMR, 3.91). As the authors note, the H1N1 virus re-emerged in 1977 after a 20-year absence, leaving young people at the time relatively unprotected.

The researchers say their morbidity findings suggest that "the age distribution of risk of infection did not differ" between the pandemic and the seasonal epidemics. They add that previous studies have shown that school-age children are most susceptible to contracting seasonal flu and that studies of the 1918, 1957, and 1968 pandemics showed an age distribution of cases similar to that of seasonal flu epidemics.

As for mortality findings, the authors write that while mortality was highest in children and younger adults, it decreased with age between 20 and 60. "Prior exposure to seasonal influenza viruses thus seems to protect against the 2009 H1N1 virus," they add. They further comment, as have others, that the relatively low mortality in elderly people suggests they have immunity related to their exposure to H1N1 viruses that circulated before 1957.

Cecile Viboud, PhD, a staff scientist in the division of international epidemiology and population studies at the National Institutes of Health's Fogarty International Center, observed that the finding of a shift in the mortality burden to younger people in the H1N1 pandemic has been detected in several other studies and also has been described in the previous three pandemics.

However, "the authors do not find evidence of an age shift in the distribution of influenza cases" in the 2009 pandemic, "which is perhaps a little surprising," Viboud told CIDRAP News by e-mail.

She said the study may lack the statistical power to detect changes in the age distribution of cases in pandemics. This is "mostly because they only have two seasonal epidemics to compare with, and also because the morbidity data come from several different studies with likely large variations in sampling and testing practices."

Viboud added that at least two previous studies "have noted a change in the age distribution of cases in [past] pandemics, with proportionally more children being sick than expected. Also, we know that seasonal A/H1N1 epidemics tend to cause illness in younger individuals than H3N2 epidemics, which is not obvious from their [Lamaitre and Carrat's] data, and suggests that the study may be underpowered."

She said another possible problem with the study is its use of data on deaths specifically coded as influenza, which underestimate the true flu burden and may introduce age-related biases in coding. She added that she looks forward to further studies on the age distribution of cases and deaths as more data on the 2009 pandemic become available.

Source: http://www.cidrap.umn.edu/cidrap/content/influenza/swineflu/news/jun1410age.html

Tuesday, June 8, 2010

Studies Needed to Address Public Health Challenges of the 2009 H1N1 Influenza Pandemic: Insights from Modeling

In light of the 2009 influenza pandemic and potential future pandemics, Maria Van Kerkhove and colleagues anticipate six public health challenges and the data needed to support sound public health decision making in the June edition of PLoS Medicine. Summary points from the group’s paper include the following:
  • As the global epidemiology of the pandemic (H1N1) 2009 influenza (H1N1pdm) virus strain unfolds into 2010, substantial policy challenges will continue to present themselves for the next 12 to 18 months.
  • Here, we anticipate six public health challenges and identify data that are required for public health decision making: Measuring age-specific immunity to infection; accurately quantifying severity; improving treatment outcomes for severe cases; quantifying the effectiveness of interventions; capturing the full impact of the pandemic on mortality; and rapidly identifying and responding to antigenic variants.
  • Representative serological surveys stand out as a critical source of data with which to reduce uncertainty around policy choices for both pharmaceutical and nonpharmaceutical interventions after the initial wave has passed.
  • Continuing to monitor the time course of incidence of severe H1N1pdm cases will give a clear picture of variability in underlying transmissibility of the virus during population-wide changes in behavior such as school vacations and other nonpharmaceutical interventions.

    The entire article is worth reading, and can be viewed by clicking on the hyperlink below.

    Source: http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000275
    Article: Van Kerkhove MD, Asikainen T, Becker NG, Bjorge S, Desenclos J-C, et al. (2010) Studies Needed to Address Public Health Challenges of the 2009 H1N1 Influenza Pandemic: Insights from Modeling. PLoS Med 7(6): e1000275. doi:10.1371/journal.pmed.1000275

Wednesday, June 2, 2010

Scientists advising WHO could recommend ending the pandemic alert

(AFP) – 1 day ago

"GENEVA — Scientists advising the World Health Organisation on Tuesday held a meeting to give their latest assessment of swine flu, in a move that could end the pandemic alert, a WHO spokesman said.

The UN health agency said the result of the confidential meeting would be announced on Wednesday.

Speaking shortly before the teleconference began, WHO spokesman Gregory Haertl said the scientists would be 'reviewing the epidemiological situation around the world' and that a 'recommendation or announcement one way or the other' would be made. Asked if the emergency committee of scientists could recommend an end to the pandemic declared by the UN health agency nearly a year ago, Haertl said: 'They could.' 'The two most likely outcomes are either the status quo or post-pandemic,' he told journalists.

WHO Director General Margaret Chan has closely followed the advice of the 15-member emergency committee headed by Australian infectious diseases expert John Mackenzie since swine flu was first uncovered in April 2009. It played a crucial role in recommending an international emergency over the new virus and scaling up different stages of alert, including the declaration of a pandemic on June 11, 2009. The committee declined to wind down the pandemic alert at its last meeting in February after the disease appeared to wane in North America and Europe.

Mackenzie said in April that he was waiting to see how A(H1N1) influenza progressed in the southern hemisphere's traditional autumn and winter flu seasons, amid predictions of a second wave. Last Friday, the WHO's weekly pandemic assessment noted that there was 'little evidence of pandemic influenza activity in the temperate zone of the southern hemisphere,' except for parts of Chile.

Haertl told journalists: 'Examining what's happening, or has not yet happened, in the southern hemisphere yet will probably be key to their discussions this afternoon (Tuesday).' "

Source: http://www.google.com/hostednews/afp/article/ALeqM5jp6SUYPWGAXOE7nHjUCvGUghK4Uw