It was a shock to both parents and health care providers to hear the latest word on nasal flu vaccines, which had long been favored as a painless and more effective alternative to flu shots for children. Not this year. An advisory panel to the U.S. Centers for Disease Control and Prevention announced last week that the nasal form is hardly effective at all at preventing flu and should not be used for the 2016-17 flu season.
How could this be? Was it another case of science telling us something inaccurate for years, until research finally uncovered the truth? The public is used to hearing what once were seemingly inarguable truths are now considered myths—the effectiveness of low-fat diets for weight control, for example, or low-cholesterol diets to prevent high blood cholesterol levels.
But the change regarding the nasal flu vaccine recommendation is made of something quite different. It wasn’t the science that changed; it was the actual effectiveness of the vaccine.
For years, studies showed the nasal mist to be not just less frightening to children, but better protection for that age group against flu, probably because it was made of live attenuated virus believed to provoke a stronger immune response. But the most recent rounds of research have found that the flu mist no longer offers that stronger immunity; in fact, it conferred almost no benefit in recent years.
A 2012 review of scientific literature published in Lancet had found that the nasal vaccine was 83 percent effective in young children. But during its most recent meeting, ACIP reviewed studies, from 2013 to 2016, and found that the nasal mist had been relatively ineffective in all of those flu seasons, the Associated Press reported. In 2015-16, the committee found, the nasal vaccine was only about 3 percent effective in children ages 2 to 17—virtually nil.
“We could find no evidence (the spray) was effective,” CDC flu expert Joseph Bresee told AP. But there is no evidence, he said, that the mist’s ineffectiveness in recent years has resulted in any increase in flu deaths.
Yet, far from making families lose faith in flu vaccines, this latest announcement should, if anything, strengthen the public’s confidence in the CDC and its Advisory Committee on Immunization Practices.
The committee meets three times a year to discuss the latest research on vaccines, and has working groups that specialize in the various kinds. As a result, ACIP's immunization schedule is based on the most up-to-date and complete research available; parents who follow the guidelines can be reassured that its recommendations on the flu and all other immunizations are based on a solid foundation of sound science. And when the latest research calls for a change of immunization advice, ACIP can be counted on to act in accordance with the science. This latest recommendation is evidence of that.
The failure of the nasal mist doesn’t mean children shouldn’t be vaccinated.
The flu kills an average of 23,000 people every year in the United States, more than all other vaccine-preventable diseases combined, and affects 5 to 20 percent of the U.S. population every year. Although many of the deaths are in older adults, 77 U.S. children died last year because of flu--many of them previously healthy, with no underlying medical conditions. In short, the flu is a big deal.
Flu shots, ACIP found, were 67 percent effective for all age groups. The only responsible conclusion was to recommend against the nasal mist and direct families to the more effective injected flu vaccine, which ACIP recommends for everyone over the age of 6 months.
That wasn’t a painless decision for the children who used to get the nasal vaccine or for doctors and medical centers that administer them to patients. Many clinics place their orders early in the year, AP reported, which could lead to problems for the vaccination programs meant for children. The nasal mist has represented only 8 percent of flu vaccinations, but a third of those for children.
Still left to be determined is why the nasal mist has lost its mojo.
One factor seems to be the H1N1 virus, one of several flu viruses targeted by the nasal mist. A January study in the journal Pediatrics found that the nasal vaccine was very effective against two other types of flu virus, but not H1N1, which has been particularly prevalent in recent years.
According to LiveScience, the particular strain of H1N1 used in the vaccine might be implicated, because studies hint that it might provoke less of an immune response. Another possibility, LifeScience reported, is that this H1N1 strain might be more susceptible to degradation at higher temperatures. But there could be other factors as well, Forbes reported, including weakened immune response after repeated use.
The decision by ACIP doesn’t mean that the nasal mist will never be effective again. There could be changes in the formulation, or changes in the predominant flu strains. Families should continue vaccinating—albeit with the kind of vaccine that pinches. Bring tissues.
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