In a reversal of its recommendation last year, the CDC Advisory Committee on Immunization Practices has voted to approve an update for the 2016-2017 season stating that the live attenuated influenza vaccine, offered as a nasal spray, should not be used in any setting.
In a 13-1 vote, with one abstention, members of the committee approved the interim recommendation based on the reported ineffectiveness of the live attenuated influenza vaccine (LAIV) over the last three influenza seasons. Data reviewed both by the Advisory Committee on Immunization Practices (ACIP) and its working group indicated the LAIV had been ineffective against influenza A (H1N1) in children aged 2 to 17 years. It also performed poorly in a study among active military.
These data ran counter to previous evidence, which indicated that LAIV had worked as well as inactivated influenza vaccine (IIV). That evidence had led the ACIP last year to recommend the use of both LAIV and IIV, with no preference between the two, in people aged 2 to 49 years. Many of the committee members this year expressed their disappointment in the LAIV’s reported ineffectiveness by voting to approve the recommendation “with regret.”
“I think it is a very sad day for the influenza vaccination program,” Nancy Bennett, MD, ACIP chairwoman, said following the vote. “I think we all had great hopes, but it’s not over. If you’ve seen one influenza year, you’ve only seen one influenza year. We may be back here next year reaching a very different conclusion.”
Among the ACIP working group’s other considerations in making their recommendation were uncertainty regarding LAIV’s effectiveness against influenza A (H3N2) and B viruses, data indicating that IIV is more effective than LAIV against influenza A (H1N1)pdm09, and a “conviction that policy should encourage use of the most effective vaccines available,” according to officials prior to the vote.
In preliminary data made available in May, from studies conducted during the 2015-2016 season, the estimated effectiveness of LAIV among children aged 2 to 17 years was 3% against any influenza virus. IIV had an estimated effectiveness of 63% against any influenza virus among the same age group. According to the CDC, the data from the 2015-2016 season follows two previous seasons of poor results for LAIV.
According to the working group, there are currently 14 million projected LAIV doses, representing about 8% of the 171 million to 176 million total maximum number of projected doses for all influenza vaccines.
Committee members were also told by the working group that providers may have difficulty purchasing other products to replace LAIV, as not all products are approved for all age groups. According to ACIP officials, the CDC has contacted manufacturers about mitigating any potential shortages.
The vote may also impact school-based vaccine programs that primarily use the LAIV. According to the working group, an estimated 5% of children were vaccinated at school in recent seasons. Of those, 55% received the LAIV.
The lone dissenting vote was cast by committee member Cynthia Pellegrini, who requested that the ACIP postpone the vote until the following morning. Not a member of the working group, Pellegrini argued she and other committee members need more time to consider the data.
“This is a lot of information to absorb on short notice and to make a very important decision,” Pellegrini, who is senior vice president of public policy and government affairs at the March of Dimes, in Washington, D.C., said. “Some of the things I’m struggling with include the differences in effectiveness data among the strains, and among the strains from year to year… On the basis of this, I would like the committee to consider postponing a vote to first thing tomorrow morning, so we have time to read through this, process it and absorb it. I know I would benefit from that.” – by Jason Laday