FluMist, the only non-injected flu vaccine licensed in the United States, has regained a place on the list of flu vaccines that the Centers for Disease Control recommends for use, ending what was effectively a two-year suspension of the popular vaccine.
The Advisory Committee on Immunization Practices — an expert panel that advises the Centers for Disease Control and Prevention on immunization policy — voted Wednesday to once again recommend FluMist’s use, though the vote may have come too late for the vaccine to play a major role in next winter’s vaccination program.
Many doctor’s offices will have already ordered their flu vaccine stocks for next season and the contracts for the publicly funded Vaccines for Children program have already been let, said Dr. Nancy Messonnier, director of the CDC’s national center for immunization and respiratory diseases.
The decision will be a relief for MedImmune, which makes FluMist, and for people in public health who see this vaccine as an important part of the response to both annual flu outbreaks and the rare but often more dangerous flu pandemics. There had been mounting concern the company, a division of AstraZeneca (AZN), would abandon the vaccine if it could not find a way back to the U.S. market.
“We are pleased that the ACIP has voted in support of a renewed recommendation for Flumist,” Gregory Keenan, AstraZeneca’s vice president for U.S. medical affairs, said in a statement. “[We] look forward to continuing to work with public health authorities to optimize protection against influenza.”
AstraZeneca signaled it will ask CDC if its purchase through its Vaccines for Children Program can be increased to include FluMist for next winter. Messonnier said at the meeting that the idea is under consideration. “That is not our typical approach,” she noted. But “there may be extenuating circumstances and so we will consider that.”
The ACIP voted to drop FluMist from the list of recommended vaccines starting in the 2016-2017 flu season after studies conducted by the CDC showed that the vaccine component that targets H1N1 flu viruses was not protecting people who got the vaccine. That decision was later extended to cover this flu season as well.
MedImmune believes it traced the problem to the virus used in the H1N1 component. It has replaced it, and testing in ferrets and in cells from human nasal passages suggests the new virus is more effective.
The motion to recommend FluMist passed by a surprising 12-to-2 vote, the outcome of which belies the unease that a number of members of the committee clearly felt about the decision they were making.
They faced, in essence, a Catch-22: It has been impossible to generate the type of data that would normally be used to make a decision like this. That’s because since the H1N1 component problem first came to light, there has been too little H1N1 flu activity in places where the vaccine is used to prove that the changes the company made to FluMist have fixed the problem.
The only way to see if the problem has been solved is to use the vaccine. But without an ACIP recommendation, the vaccine’s use in the U.S. would remain minimal.
Further complicating that equation is the fact that influenza is so unpredictable there is no way to know when there will be enough H1N1 activity to show whether the tweaks were successful.
“The effectiveness of this formulation against [H1N1] is not known, and is likely to remain unknown until the next H1N1 predominant season, presuming adequate uptake of vaccine. We can’t predict when this will occur,” the CDC’s Dr. Lisa Grohskopf, who presented the report of the ACIP’s influenza working group, told the committee.
The group grappled with how to proceed, with several voting members — and nonvoting members representing groups like the American Academy of Pediatrics and the National Association of Pediatric Nurse Practitioners — voicing concern about a recommendation a number felt would confuse both the public and health care providers who administer flu vaccines.
In particular, some questioned whether the data MedImmune presented — which also compared immune responses of children given a reformulated FluMist with a new H1N1 component to the responses of children who received the prior version — could be used as a proxy for studies that showed the updated vaccine actually was more protective.
“I’m a little concerned about whether it would be interpreted that we’re compromising our interpretation of the science,” said Dr. Henry Bernstein, a pediatrics professor at the Zucker School of Medicine at Hofstra/Northwell. Bernstein voted against the recommendation.
In the end, a proposal to word the recommendation neutrally — not to say that ACIP recommended FluMist, but rather that it was among flu vaccines providers could use — provided a compromise that secured the vote’s passage.
But a number of members of the committee expressed concern that restoring FluMist to the recommended vaccines list before there is evidence to prove the H1N1 problem has been fixed could further undermine the battered reputation of flu vaccines, especially if it turns out that the change MedImmune made did not improve the vaccine’s performance.
Paradoxically, studies done in several other countries where the vaccine is used did not show the level of H1N1 failure recorded by the CDC studies. But the CDC studies were larger, which adds weight to their findings.
The vaccine is also licensed in Canada, Germany, Finland, Sweden, Norway, Austria, and the United Kingdom, where it is the recommended vaccine for children between the ages of 2 and 9. But the U.S. traditionally represented the bulk of the vaccine’s sales.
FluMist is puffed into a nostril using a sprayer. Unlike injectable flu vaccines, it contains live viruses that act by initiating infections. But the viruses are attenuated — weakened — which means the immune system can shut down the infection before symptoms develop. That process trains the immune system to be on guard for viruses like the ones in the vaccine.
Initially the vaccine had appeared to be more effective in children than injectable flu vaccines and for a year, it had a rare preferential recommendation — a signal from ACIP that the vaccine should be used over flu shots for children.
But over time, as it became apparent there was a problem with the H1N1 component of FluMist, it lost the preferential status and then its ACIP endorsement altogether.
Wednesday’s vote means it will likely be more widely used next winter. But it will take time for the vaccine to regain its previous market share.