For more than a decade, millions of children have avoided the prick of the flu shot by getting the vaccine sprayed up their noses. But this fall, most parents taking their kids in for flu vaccination will find that their pediatricians are not offering the FluMist spray.
I've been looking into what's going on and have answers to all of your questions below.
What is FluMist and why has it been so popular?
FluMist was initially licensed in 2003. Instead of being injected into their arms, it's sprayed into their noses.
It's proved to be a popular alternative for shot-averse kids: Data from recent flu seasons suggests that the nasal spray accounted for about one-third of all flu vaccines given to children, according to the Centers for Disease Control and Prevention.
Beyond the way it's administered, there's another difference between the nasal spray and the flu shot: The nasal spray is a live, attenuated vaccine, meaning it contains live, but weakened, flu viruses. The flu shot, meanwhile, is an inactivated vaccine.
The nasal spray's manufacturer, MedImmune, explains on its website that the vaccine, "stimulates the immune system in the lining of the nose and throat," because, "that is where the flu virus enters the body."
Why would doctors stop using the nasal spray?
The CDC says during last year's flu season, the nasal spray vaccine provided no statistically significant benefit to children ages 2 to 17. It says the nasal spray was just 3 percent effective in preventing the flu.
And last year wasn't much of an outlier: The CDC says data from the previous two flu seasons also show that the nasal spray had poor or lower than expected effectiveness.
Does the CDC know why FluMist became so ineffective?
No. But Dr. Hank Bernstein, professor of pediatrics at Hofstra Northwell School of Medicine, has some hypotheses.
When the nasal spray vaccine was introduced in 2003, it protected against three strains of flu. An international study published in the New England Journal of Medicine in 2007 found the nasal spray to be more effective than the regular flu shot. But the nasal spray began protecting against four strains of flu in 2013, and hasn't been as effective since then.
Bernstein says one hypothesis is that the addition of the fourth strain may have caused some sort of interference with the other strains in the vaccine.
As a live vaccine, the nasal spray generates an immune response by virus replication in the nose. Another hypothesis, Bernstein says, is that the amount of replication might be blunted, since the kids have already been vaccinated in past years.
"Many of them have received influenza vaccine several times, because it is recommended each and every year, and the question is, did that influence how well the body's immune system responded to the intranasal vaccine?" says Bernstein, who's also associate editor of The Red Book Online, the American Academy of Pediatrics' guide to infectious diseases.
What are health experts saying about FluMist?
The CDC's Advisory Committee on Immunization Practices, which develops vaccination recommendations for the country, voted in June to not recommend the use of the nasal spray vaccine during the 2016-2017 flu season, while continuing to recommend that everyone age 6 months and older get the flu vaccine shot.
The American Academy of Pediatrics followed the group's lead. Last week, it also advised pediatricians to not use the nasal spray this year.
These recommendations are having immediate effects: Kaiser Permanente, for example, is only offering the injectable flu shot this year, according to Southern California spokeswoman Mayra Suarez.
Bernstein acknowledges that some parents and children will be disappointed that the nasal spray is not an option this year, but he stresses that it's still really important that everyone – children and adults – get a flu shot.
"We're encouraging and educating families on the importance of flu vaccine," he said, adding that people should get immunized as soon as shots are available, since it's hard to predict when flu season will ramp up.
Is there any concern there won't be enough flu shots now?
In June, the CDC said the makers of the nasal spray vaccine had projected a supply of as many as 14 million doses - or about 8 percent of the country's projected supply of flu vaccine.
The agency expects there to be sufficient supply of flu vaccine this year, although "providers may need to check more than one supplier or purchase a flu vaccine brand other than the one they normally select," says CDC spokeswoman Kristen Nordlund.