The US Centres for Disease Control and Prevention’s (CDC) advisory committee on immunisation practices (ACIP) has voted in favour of renewing the recommendation for the use of live attenuated influenza vaccine (LAIV) Flumist® Quadrivalent for the 2018-2019 influenza season.
The recommendation was based on new data which showed that the 2017-2018 H1N1 LAIV post-pandemic strain performed significantly better than the 2015-2016 strain. “This study validates the improvements we’ve made to our strain selection process and confirms an improved H1N1 LAIV strain was included in the 2017-2018 formulation,” said Gregory Keenan, vice president, US medical affairs, AstraZeneca.
In 2016, the ACIP had recommended that the LAIV, or the “nasal spray” flu vaccine, should not be used during the 2016-2017 flu season. A review of data from 2013 through 2016 showed that the vaccine offered children almost no protection against flu; in the 2015-2016 season LAIV protection rate was only 3%.
According to the new study, the antibody response induced with the 2017-2018 LAIV strain was comparable to that seen with the strain included in the vaccine before the 2009 influenza pandemic. The study included 200 children between the ages of 2 to <4 years; after the first dose, 23% of children vaccinated with the 2017-2018 LAIV strain developed a 4-fold antibody rise, compared to 5% with the 2015-2016 LAIV strain. This increased to 45% and 12%, respectively, after the second dose.
Flumist Quadrivalent remains available in limited quantities for the current season and, pending strain approval by the US Food and Drug Administration, it will be available for the 2018-2019 influenza season. The vaccine is approved for use in persons 2 through 49 years of age.
The vote for FluMist, the only non-injected flu vaccine licensed in the US, may have come too late for the vaccine to play a major role in next winter’s vaccination programme, says a STAT News report. Dr Nancy Messonnier, director of the CDC’s national centre for immunisation and respiratory diseases is quoted as saying that 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 Programme have already been let.
But, the report says, 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, would abandon the vaccine if it could not find a way back to the US market.
“We are pleased that the ACIP has voted in support of a renewed recommendation for Flumist,” Keenan said. “(We) look forward to continuing to work with public health authorities to optimise protection against influenza.”
AstraZeneca signalled it will ask CDC if its purchase through its Vaccines for Children Programme 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 report says 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.
The report says 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 US would remain minimal.