Green light for nasal flu spray next year after 2-year ban

A CDC panel ruled that doctors can use the nasal spray flu vaccine as a first line of protection for children next year.

For the last two years, the federal agency’s vaccine advisory panel has refused to endorse the spray. 

Some research has found that the vaccine, known by the brand name FluMist, did not protect against certain strains of the flu. 

The Advisory Committee of Immunization Practices voted Wednesday to recommend the nasal spray as an option for next winter’s flu season, and experts say it might have protected more Americans from illness this year.

The Centers for Disease Control and Prevention has spent the last five months urging everyone over six months of age to get one of the two flu shots it recommended this year.

But, as officials announced last week, each of these was only about 36 percent effective against the flu this season. 

The shots were particularly weak protection against the aggressive H3N2 strain that has dominated the 2017-2018 season, preventing only 25 percent of adults from getting the bug.  

The shot was somewhat better at protecting children – about 59 percent effective – though they undoubtedly would prefer the spray. 

Unlike most countries, neither of the flu shots recommended in the US this season contained any live attenuated influenza virus (LAIV), the active ingredient in FluMist.    

FluMist, the only nasal spray vaccine approved in the US, was found to be relatively ineffective in recent years, particularly against the H1N1 strain of the flu that was responsible for the majority of illnesses during the 2015-2016 season.

In order for a live virus vaccine to be safe and effective for use humans, it has to strike just the right balance between replicating enough to activate an immune response, but not enough to cause the illness itself. 

FluMist’s past poor performance against H1N1 may mean that scientists at AstraZeneca, which makes the vaccine, picked proteins that were too weak. 

The company presented a data from a small study to the Advisory Committee of Immunization Practices during its meeting today. 

‘They probably fixed the H1N1 component in some way, [possibly by] picking proteins used in this particular LAIV that replicated better,’ says Dr Andrew Pekosz, a Johns Hopkins University immunology professor who has studied the spray.

It is difficult for even the foremost experts to predict what strains of the flu will strike each season, and pure coincidence that H1N1 did not come around the last two seasons.

But, ‘for the last two years when [FluMist] was not on the market, we’ve had H3N2, something [the spray] should have been good at’ protecting against, Dr Pekosz says.  

‘The strains of flu that are circulating are the ones that an LAIV has been working well for, so it probably would have helped us these last two seasons,’ he adds.

He notes that the spray was ‘utilized extensively in pediatric patients’ during years when it was recommended by the CDC for adults and children over two.  

This year, 84 children have died so far, and more are expected to succumb to the flu. 

Both children and adults are anecdotally more likely to accept the flu spray, says Pekosz, because it does not involve 

The nasal spray vaccine can also offer faster protection directly to the parts of the body the flu attacks.

The shot ‘activates in your arm, and generates a response in your blood, but what we really want to do is generate an immune response at the surface where [the virus] enters the body.

‘That’s what the FluMist does really well: it induces a mucosal response in your respiratory tract,’ where we typically inhale the flu virus, Dr Pekosz says. 

For this reason the nasal spray is ‘probably going to be a little better at stopping the flu virus in the first place,’ he adds. 

‘It is difficult to predict, but we usually don’t see two flu seasons with the same strain, so next year is probably going to be heavy on H1N1, so having an LAIV that is effective against H1N1,’ as he hopes FluMist will now be, ‘is a great tool to have against influenza next year,’ Dr Pekosz says.