The FluMist experience
The FluMist episode is viewed by many European pediatric infectious disease experts as a debacle. Europeans eager to develop a pan-European strategy for seasonal immunization against influenza in children and adolescents viewed the U.S. FluMist episode with dismay. For the 2016-2017 and 2017-2018 flu seasons, the ACIP recommended against FluMist, a previously approved intranasally administered quadrivalent live attenuated virus vaccine, on the basis of a single study showing subpar effectiveness against influenza A H1NI. Then at its October 2017 meeting, ACIP reversed itself and reinstated FluMist for the 2018-2019 season after viewing data from Finland and several other countries demonstrating that, in countries where it hadn’t been taken off the market, the vaccine had performed as well as injectable inactivated influenza vaccines in the 2016-2017 flu season.
“I think from the European side, it’s been a bit of a sorry spectacle,” commented Dr. Osterhaus, referring to the ACIP’s waffling. After all, authorities in Canada and European countries where FluMist was available had looked at the same data that caused ACIP to derecommend the vaccine but hadn’t found it convincing.
“We’re very happy to see ACIP has reinstated the vaccine,” Dr. Nohynek said.
Dr. Abramson declined to defend the ACIP decision to drop FluMist.
“From my standpoint, knowing that influenza B kills more children than A does, if I had been on the ACIP committee – and I’m not anymore – that would not have been my vote,” he said. “Whatever you want to say about the live attenuated influenza vaccine, about how good it is against some A strains or not, it’s better than other vaccines against influenza B. And the death rate is higher from B than A in children, although that is not true in adults.”
Plus, FluMist was an important option for people avoiding immunization because they dislike shots.
“The vast majority of deaths due to flu in children in 2010-2016 have been in kids who didn’t get vaccinated,” he noted.
Dr. Nohynek said the Finnish real-world experience recorded in comprehensive national registries for the 2017-2018 flu season – a bad year for vaccine/virus mismatch in Europe – confirmed Dr. Abramson’s comments about the superiority of quadrivalent live attenuated influenza vaccine against influenza B. Among 54,611 Finnish children aged 24-35 months, the laboratory-confirmed vaccine effectiveness of trivalent inactivated virus vaccine, with 9% coverage, was 4.5% for influenza A and 12.2% for influenza B. In contrast, the vaccine effectiveness for the intranasal quadrivalent live attenuated influenza vaccine was 32% for A and a whopping 80% for B.
“It’s quite amazing, at least to me, to see figures like this in real world data,” she commented.
Session cochair Adam Finn, MD, PhD, said he has found it instructive to take a closer look at the U.K. data for the past several flu seasons.
“We’ve seen greater control of the epidemic in Scotland and Northern Ireland, where coverage in primary school kids was higher, in the 60%-70% area, and lower in England and Wales, where it was more like 50%. So we’re beginning to think that’s the kind of level of annual coverage in children we might need to suppress an epidemic. I think that’s a really important message that people should understand: We’re not looking for 95% coverage,” observed Dr. Finn, aprofessor of pediatrics at the University of Bristol (England).