FDA Advisers Pick 2016-2017 Influenza Vaccine Strains

Alicia Ault

March 04, 2016

SILVER SPRING, MD — A US Food A US Food and Drug Administration (FDA) advisory committee has recommended two changes for the influenza vaccine for the 2016-2017 season.

The Vaccines and Related Biological Products Advisory Committee today unanimously voted to adopt the World Health Organization's (WHO) recommendations for the 2016-2017 influenza vaccine for the northern hemisphere.

The WHO recommendations are based on global surveillance of circulating influenza strains and on the effectiveness of the northern hemisphere vaccine for the 2015-2016 season.

The US Centers for Disease Control and Prevention (CDC) previously reported that the 2015-2016 influenza vaccine had an overall effectiveness of 59%, with a 51% rate for the A(H1N1) component and 76% effectiveness against B strains. Overall, 146.4 million vaccine doses have been distributed in the US, according to the CDC.

For the vaccine for the northern hemisphere's influenza season that will begin in the fall of 2016, WHO recently recommended including the A/California/7/2009 (H1N1)pdm09-like virus, A/Hong Kong/4801/2014 (H3N2)-like virus, and B/Brisbane/60/2008-like virus (B/Victoria lineage), with the addition of B/Phuket/3073/2013-like virus (B/Yamagata lineage), for the quadrivalent vaccine.

These same strains were recommended in September by WHO for the southern hemisphere's 2016 winter vaccine.

The H3N2 strain and the B strain will be new for the US and northern hemisphere 2016-2017 trivalent vaccine. In 2015-2016, the trivalent vaccine included A/California/7/2009 (H1N1)pdm09-like virus, the A/Switzerland/9715293/2013 (H3N2)-like virus, and the B/Phuket/3073/2013-like virus. The quadrivalent vaccine included B/Brisbane/60/2008-like virus.

This Year's Flu Season

Surveillance data for the 2015-2016 influenza season so far indicates low activity, said researchers from the CDC.

In the US, almost 70% of the specimens characterized by the CDC have been A strains, with a slight majority being A/California/7/2009 (H1N1)pdm09-like, said Lisa Grohskopf, MD, MPH, associate chief for policy and liaison activities in the CDC's influenza division. The specimens in which a B virus caused illness were almost all either B/Phuket/3073/2013-like or B/Brisbane/60/2008-like virus.

Influenza activity has been higher outside of the US, with illness caused by A(H1N1)pdm09 viruses — the most frequently detected — higher than seen in the 2014-2015 northern hemisphere flu season, said Jacqueline Katz, PhD, acting deputy director of the CDC's influenza division.

Surveillance indicates some genetic drift in that strain, but the new forms are still similar to the recommended vaccine virus strain of A/California/7/2009, said Dr Katz, also director of the WHO Collaborating Center for Surveillance at the CDC.

Type A(H3N2) viruses are also showing some genetic changes, but the strains circulating around the globe are still covered by the vaccine, she said. The B viruses have caused mostly local or sporadic illness outside the US, with the exception of Canada and Brazil, which have reported widespread B-related outbreaks. B/Victoria lineage viruses are still dominating in most areas of the world, but the Yamagata lineage has begun taking over in some areas and is on the increase in the US, Dr Katz said.

Unlike the 2014-2015 influenza season, illnesses and deaths from the virus have been fairly modest in the US so far this flu season.

For the week ending February 6, almost 7% of all US deaths were due to pneumonia and influenza, according to the National Center for Health Statistics Mortality Surveillance System. That is above the baseline, but still not unprecedented, said Dr Grohskopf.

Pediatric deaths have dipped dramatically. In 2014-2015, the CDC reported 148 pediatric deaths due to flu. As of February 6, 14 deaths had been reported.

Based on data gathered by state and territorial health authorities, the CDC is reporting widespread flu in 21 states, Puerto Rico, and Guam; regional illness in 18 states; local outbreaks in 10 states and Washington, DC; and sporadic illness in one state and the US Virgin Islands.

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