Medscape Medical News

Troy Brown, RN

February 28, 2014

 

The US Food and Drug Administration's (FDA) Vaccines and Related Biological Products Advisory Committee unanimously recommended at a meeting today that the virus strains used for the 2014-2015 northern hemisphere influenza season vaccine should remain the same as those in the 2013-2014 vaccine.

 

The decision follows recommendations made by the World Health Organization (WHO) in Geneva, Switzerland, on February 20. The FDA committee is under no obligation to endorse the WHO's recommendations, Robert Daum, MD, voting member and chair, Vaccines and Related Biological Products Advisory Committee, instructed the panel. Although WHO met before the FDA did this year, it hasn't always been that way, he added.

 

"As you know, WHO has already voted and said yes but that doesn't mean we have to," Dr. Daum said.

 

The 2013-2014 seasonal influenza vaccine is outperforming the previous year's vaccine, according to the Centers for Disease Control and Prevention. The 2013-2014 vaccine reduces a person's risk of requiring medical care for influenza illness by 61%, compared with an effectiveness rate of 51% for the 2012-2013 influenza season vaccine.

 

 

The committee recommended (16 yes, 0 no, 0 abstain) that the 2014-2015 vaccine should contain:

 

•  an A/California/7/2009 (H1N1)-like virus (current vaccine strain);

 

•  an A/Texas/50/2012 (H3N2)-like virus (current vaccine strain); and

 

•  a B/Massachusetts/2/2012-like virus (B/Yamagata lineage) (current vaccine strain).

 

 

The committee recommended (16 yes, 0 no, 0 abstain) that the 2014-2015 quadrivalent vaccines containing 2 influenza B viruses should contain the above 3 viruses and a B/Brisbane/60/2008-like virus (Victoria lineage), which is a recent vaccine strain and current quadrivalent vaccine recommended strain.

 

Approximately 50% of vaccines manufactured will be trivalent and 50% will be quadrivalent vaccine, said Sam Lee, PhD, senior director for Sanofi Pasteur's Pandemic Influenza Strategy.

 

 

A(H1N1)pdm09 viruses cocirculated with A(H3N2) and B viruses in varying proportions during the period of September 2013-January 2014, with outbreaks in several countries. Most A(H1N1)pdm09 viruses were antigenically similar to A/California/7/2009. Vaccines that contained A/California/7/2009 antigens elicited anti-HA antibodies in humans of similar titres against the vaccine virus and recent A(H1N1)pdm09 viruses.

 

Influenza A(H3N2) viruses were linked with outbreaks in several countries. Most recent viruses were antigenically and genetically similar to the cell-propagated A/Texas/50/2012 viruses. The majority of A(H3N2) viruses isolated since September 2013 were inhibited by ferret antisera raised against A/Texas/50/2012. Vaccines that contained A/Texas/50/2012 antigens elicited antibodies in humans of similar geometric mean HI titres to the cell-propagated vaccine virus and most representative recent A(H3N2) viruses.

 

 

Many countries reported influenza B activity with B/Yamagata/16/88 lineage viruses predominating.

 

B/Yamagata/16/88 viruses recently reported belonged to the HA phylogenetic clades 2 or 3 and were antigenically similar to B/Massachusetts/2/2012-like (clade 2) viruses.

 

Current vaccines that contained B/Massachusetts/2/2012 antigens elicited anti-HA antibodies in humans with similar titres against the vaccine virus and recent viruses of the B/Yamagata/16/88 lineage.

 

Most of the small number of recent B/Victoria/2/87 lineage viruses detected were antigenically and genetically closely related to B/Brisbane/60/2008.

 

Vaccine effectiveness rates were lower in the armed forces, but the reasons for this are unclear.

 

"I am concerned about the data we heard this morning," Dr. Daum said. He added that he believes these concerns should be addressed at another time, "but our job today is to assume that…the vaccine is still the best way that we have of preventing influenza.

 

"There hasn't been a driving force to change [virus strains] this year, but [in] other years, we've changed everything," Dr. Daum explained.

 

The voting members have disclosed no relevant financial relationships.

 

Recommended composition of influenza virus vaccines for use in the 2014-2015 northern hemisphere influenza season. WHO. 2014:1-15. Full report