The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC) voted to recommend that live attenuated influenza vaccine (LAIV; FluMist Quadrivalent, MedImmune) should not be used in the United States for the 2016 to 2017 influenza season. LAIV is the only nasal spray influenza vaccine; the CDC recommends annual influenza vaccination for all persons aged 6 months and older and says people should use either the inactivated influenza vaccine (IIV) or recombinant influenza vaccine instead.
ACIP is a committee of immunization experts that advises the CDC; this is an interim recommendation for the 2016 to 2017 influenza season, as data may be different in future seasons.
Case in point, the ACIP endorsed the quadrivalent nasal spray over influenza shots for children aged 2 to 8 years in 2014.
The vote (13 yes, 1 no, 1 abstain for conflict of interest) follows a review of new data that show LAIV has been ineffective for the last three influenza seasons (2013-2014 through 2015-2016) in children aged 2 to 17 years. The new data show that IIV is more effective than LAIV against influenza A(H1N1)pdm09, and there is uncertainty about whether or not LAIV quadrivalent (LAIV4) is effective against influenza A(H3N2) and influenza B viruses.
Preliminary data from the US Influenza Effectiveness Network showed that during the 2015 to 2016 season, LAIV vaccine effectiveness against any influenza virus among children aged 2 through 17 years was only 3% (95% confidence interval, −49% to 37%) compared with 63% (95% confidence interval, 52% - 72%) for IIV. LAIV vaccine effectiveness was also "poor and/or lower than expected," during the 2014 to 2015 and 2013 to 2014 seasons, according to a CDC news release.
There are fewer data in adults, but tests in active military personnel showed poor vaccine effectiveness for LAIV3/4 against A(H1N1)pdm09.
Data about the effectiveness of LAIV before and soon after licensure suggest it was at least as effective as IIV. The US Food and Drug Administration approved quadrivalent LAIV in February 2012. An earlier trivalent version of LAIV was approved in June 2003 and was later replaced by the quadrivalent formulation.
Tom R. Frieden, MD, MPH, director of the CDC, addressed the committee before the meeting; he acknowledged that yesterday's decision was a challenging one, but urged the committee not to postpone it. "In public health, we are often faced with a situation of having to take action based on what we know today, because if there is one thing we always have to keep in mind, [it is that] a nondecision is also a decision," he said.
The committee discussed potential programmatic implications of taking the LAIV off the table. There are a total of 171 to 176 million projected influenza vaccine doses; LAIV accounts for 8% (14 million projected doses) of the total projected influenza vaccine supply. Providers may have difficulty purchasing other vaccines, and not all vaccine products are licensed for all age groups.
Some 5% of schoolchildren were vaccinated against influenza at school in recent seasons. Of those, 55% received LAIV.
LAIV Off the Table Entirely for Upcoming Influenza Season
The committee was asked to vote on whether to recommend that LAIV not be used at all, or whether it could be used in certain situations in which a person might not otherwise be vaccinated, such as when IIV is not available or when a patient or their parent refuses an injectable vaccine such as IIV.
"Dr Frieden had certainly seen this data before he came this morning. What he tried to focus on was the need to make decisions based on imperfect data, and that, as a science-driven group, you have to make a decision about whether we have actionable data," Nancy Messonnier, MD, director, National Center for Immunization and Respiratory Diseases, CDC, said. Dr Messonnier is an Ex Officio committee member.
"My understanding from the working group deliberations is that despite the fact that there are discrepancies in the data, the working group felt strongly that this data was actionable...where they fell out of consensus was whether that was an absolute, 'you should not use this vaccine,' which is what [the American Academy of Pediatrics] is saying, or whether or not — partly because of some of these programmatic issues, which [the American Academy of Family Physicians] is pointing out — there should be some space where, if clinicians didn't have another option, it was better to give this than nothing," Dr Messonnier explained.
"It's the younger adults and children who tend to get more severe disease with H1N1, which is also the group that the IIV is targeted for," said voting committee member Kelly Moore, MD, MPH, director, Tennessee Immunization Program, Tennessee Department of Health, and assistant clinical professor, Department of Health Policy, Vanderbilt University School of Medicine, Nashville, Tennessee. "I would not feel comfortable knowing ahead of time that [LAIV] wouldn't work against that or there is not evidence of effectiveness."
Dr Moore added, "The public looks to us to make recommendation about the best possible vaccine.... We can find other places, other providers for those children to get vaccines if there are individual spot shortages."
The CDC's director must review and approve the committee's recommendation before it becomes CDC policy.
Reasons for Ineffectiveness Unclear
A number of factors can affect how well the influenza vaccine works, and its effectiveness can vary a great deal from season to season. These factors include characteristics of the person receiving the vaccination, the similarity between viruses used in the vaccine and circulating viruses, and which vaccine is being used. LAIV vaccines, which contain live, weakened influenza viruses, can stimulate a stronger immune response than IIV vaccines, which contain inactivated virus.
Vaccines for Children Program
The committee voted (13 yes, 1 no, 1 abstain for conflict of interest) to remove LAIV from the Vaccines for Children (VFC) program. The IIV component of the program will not be changed.
The VFC program is a federally funded program that provides free vaccines to children who are unable to pay for them.
"For VCF vaccines, providers receive those; they don't purchase [or] pay for those. We provide contracts and make doses available to states for the VFC program...we will make vaccines available for children that are covered by the VFC program, and those are the vaccines that providers in the VFC program will get and will be able to administer," Jeanne Santoli, MD, MPH, deputy director, Immunization Services Division, National Center for Immunization and Respiratory Diseases, CDC, explained.
"[Providers] don't bill for those; they bill for the administration fee, and that will happen as normal, but this is limiting what the formulary will be for the vaccines in the VFC program this year," Dr Santoli added.