Pandemic H1N1 Virus Should Be Added to 2010-2011 Seasonal Influenza Vaccine, Says WHO

Robert Lowes

Authors and Disclosures 

February 18, 2010 — The World Health Organization (WHO) recommended today that the 2010-2011 seasonal influenza vaccines for the northern hemisphere should include a strain of the "dominant" pandemic A (H1N1) virus, as well as 2 nonpandemic influenza strains.
National public health authorities will decide whether to include a strain of the pandemic virus in the traditional trivalent vaccine or administer it separately as a monovalent vaccine, said Keiji Fukuda, MD, MPH, the special pandemic influenza advisor to the WHO director-general, at a press conference today.
WHO is dropping the older, nonpandemic seasonal A (H1N1) virus strain from its recommended mix because it does not expect this strain to circulate at significant levels.
The decision to replace the nonpandemic A (H1N1) strain with a pandemic strain was based on input from a WHO advisory committee composed of experts mostly from the laboratories and national public health agencies that make up the WHO Global Influenza Surveillance Network.
"In essence, what the scientists said was that in the past year, the overwhelming number of influenza viruses isolated around the world were the pandemic H1N1 virus," said Dr. Fukuda. "The experts believe, based on this information, that these viruses will continue to be one of the dominant viruses in the coming fall and winter season in the northern hemisphere."
Trivalent Vaccine with Pandemic Strain Makes Sense for Countries "That Use a Lot of Seasonal Flu Vaccine"
The 3 influenza strains recommended by WHO for northern hemisphere vaccines are an 

1) A/California/7/2009 (H1N1)–like virus, which is a pandemic strain; an 
2) A/Perth/16/2009 (H3N2)–like virus; and a 
3) B/Brisbane/60/2008-like virus.

In September 2009, WHO recommended these same strains for seasonal influenza vaccines for the southern hemisphere in 2010. WHO issues these recommendations for vaccine composition each September and February for the southern and northern hemispheres, respectively, for the coming influenza season.
If national public health authorities choose to use the pandemic strain for a monovalent vaccine, then the other 2 strains could make up a second vaccine.
Dr. Fukuda said a trivalent vaccine containing the pandemic virus would make sense for countries "that use a lot of seasonal flu vaccine."
Vaccine manufacturers and national governments, he said, would theoretically be able to use their current stockpiles of pandemic vaccines in bulk form for 2010-2011 seasonal vaccines in a trivalent formulation. In contrast, pandemic vaccine already packaged in vials and syringes could not be reused.
Dr. Fukuda emphasized that the recommendation to give seasonal-vaccine status to the pandemic influenza virus does not mean that the current pandemic is over. However, a WHO emergency committee will convene next week to decide whether the pandemic has entered an official "postpeak period," which means the worst is over, although the pandemic virus continues to cause sickness and even cause outbreaks in new regions. As proof, Dr. Fukuda noted that WHO has received new reports this week of communitywide transmission of the pandemic virus in Mauritania, which comes on the heels of outbreaks in neighboring Senegal.

• H1N1 Influenza A (Swine Flu) Alert Center

Medscape Medical News

WHO to Consider Whether H1N1 Pandemic Has Peaked

Robert Lowes

February 11, 2010 — An emergency advisory committee of the World Health Organization (WHO), meeting later this month, will consider making it official what WHO has indicated for weeks — that the H1N1 influenza pandemic, although still active in many parts of the world, is winding down.
However, at a press conference today, Keiji Fukuda, MD, MPH, the special pandemic influenza advisor to the WHO director-general, cited a recent outbreak of H1N1 infection in Senegal as proof that the pandemic has not run its full course.
"We are seeing an overall declining pattern in the Northern Hemisphere, but it's very clear the virus hasn't disappeared," said Dr. Fukuda. "It's continuing to cause disease and death in many parts of the world."
Dr. Fukuda said WHO has received its first reports of communitywide infection in Senegal, where there have been 42 mild cases of pandemic H1N1 influenza, but no deaths. "Western Africa is one part of the world where we haven't seen much activity," he said. "We may be seeing a general decline, but in some places community outbreaks can [still] be expected."
The emergency committee, formed under the International Health Regulations approved by WHO member states, will review epidemiologic data and then recommend whether WHO should classify the pandemic as having entered a postpeak, or transition, phase, said Dr. Fukuda.
The postpeak phase is part of a pandemic classification system used by WHO that immediately follows phase 6, which marks a full-blown pandemic. In a postpeak period, according to WHO's Web site, "pandemic activity appears to be decreasing; however, it is uncertain if additional waves will occur and countries will need to be prepared for a second wave." Official designation of the postpeak period will help national public health authorities plan for the future, Dr. Fukuda said.
The final stage in the WHO spectrum is the postpandemic period. Here, influenza disease activity returns to "levels normally seen for seasonal influenza."
Dr. Fukuda said he expects the emergency committee to meet during the last week of February, although an exact date has not yet been set.
H1N1 Could Be Component of Next Seasonal Flu Vaccine for Northern Hemisphere
Dr. Fukuda also announced that WHO will convene its annual meeting of experts next week to begin deliberating on which influenza virus strains should make up the 2010-2011 seasonal influenza vaccine for the Northern Hemisphere. These experts hail from national public health agencies and laboratories that make up the WHO Global Influenza Surveillance Network. Dr. Fukuda said that this group will likely consider including the pandemic H1N1 virus as 1 of the 3 strains normally constituting the seasonal influenza vaccine.
"I don't want to second-guess what the expert advisors will recommend," said Dr. Fukuda. "But it's fair to point out that the current pandemic virus is by far the most common virus that's been isolated around the world. It's a good bet we'll see it around for quite a while."
Each September, WHO convenes the same experts to recommend the composition of the next year's seasonal influenza vaccine for the southern hemisphere. At their meeting in September 2009, they included a strain of the pandemic H1N1 virus — specifically, an A/California/7/2009 (H1N1)-like virus — as 1 of the 3 strains for 2010. The other recommended strains were an A/Perth/16/2009 (H3N2)-like virus and a B/Brisbane/60/2008-like virus.
Another WHO advisory group, the Strategic Advisory Group of Experts on Immunization, recommended last year that nations ordering vaccines should have the option of either including a pandemic H1N1 virus in the traditional trivalent vaccine for seasonal influenza or making it a separate monovalent vaccine, with the other 2 recommended strains in a second vaccine.
"This Is a True Pandemic"
Dr. Fukuda continued to defend WHO against charges issued by European critics that profit-minded vaccine manufacturers swayed the agency to exaggerate the severity of the H1N1 outbreak. "Our position is very clear," he said. "This is a true pandemic."
WHO, he said, is currently assessing how WHO and other national public health agencies performed in responding to the pandemic so they can "do it better the next time." However, this investigation is not based on allegations by any particular individuals, he added.