A: The flu shot and flu nasal spray vaccines are about equally effective at preventing influenza illness and complications.
There are many flu vaccine options, but the best thing is for all people age 6 months and up to get vaccinated. The best flu vaccine is the one you can (and are willing) to get!
Influenza bites. Flu symptoms hit you all of a sudden and include fever, cough, sore throat, runny nose, body aches, and fatigue. The flu can cause mild to really bad illness. In the US between 2010 and 2020, the CDC estimated that flu caused 9-41 million illnesses; 140,000-710,000 hospitalizations; and 12,000-52,000 deaths every year. One of the best ways to prevent all of this is the flu vaccine.
The flu vaccine comes in both shots and a nasal spray. There are different types of flu shots (standard dose, high dose, egg free cell based, adjuvanted, and recombinant) and we can get into the details of different flu shots in another post. There is also a nasal spray flu vaccine, called FluMist. It is sprayed in the nose: 1/2 of the dose in each nostril. This is a live attenuated influenza vaccine (you may see if referred to as LAIV). The nasal spray is made up of weakened live influenza virus (the shots do not contain live virus). The weakened viruses in the nasal spray are cold-adapted, meaning they are designed to only replicate at cooler temperatures found in the nose and not in the lungs where it is warmer. Some people prefer it because it isn’t a shot and doesn’t require any needles.
How effective the flu vaccines are vary from year to year and depend on the circulating strain of flu virus, vaccine type, and by age and risk factors. After the 2009 influenza pandemic, there was a series of studies that showed that the nasal spray was as effective as the shot against some types of influenza virus (influenza B viruses and influenza A(H3N2) viruses) but not as effective against the H1N1 influenza virus. This caused the CDC to recommend against using the nasal spray during the 2016-2017 and 2017-2018 flu seasons. Since then, the manufacturers have switched to new influenza H1N1 vaccine virus ingredients when making the nasal spray. The nasal spray isn’t used as commonly in the US, so there isn’t really good data on the new ingredient efficacy from US trials. However, data from other countries show that this new and improved LAIV has similar efficacy to the standard dose inactivated flu vaccine shots in kids.
The nasal spray is available for healthy, non-pregnant people ages 2 to 49 years old. Not everyone can get the nasal spray though. People with certain medical conditions (like weakened immune systems, cochlear implants, asthma, or don’t have a spleen) should not get the nasal spray. It should not be given to people who had the flu and recently took antiviral flu medications (48 hours for oseltamivir and zanamivir, 5 days for peramivir, and 17 days for baloxavir). Antiviral flu medicines might reduce the effectiveness of the nasal flu vaccine. Check out the Advisory Committee on Immunization Practices detailed report for the full list of conditions and situations that should not get the nasal flu vaccine.
To sum it up: the nasal spray and flu shot are about equally effective. The CDC, American Academy of Pediatrics, and American Academy of Family Physicians recommend any licensed influenza vaccine appropriate for a person’s age and health status. For people under the age of 65, there is no preference for one product or another. It all comes down to what you can get and are willing to take. If you cannot stand needles or getting your kids to get a flu shot is a massive fight every year, the nasal spray may be a good choice.
Stay safe. Stay well.
Those Nerdy Girls
Links:
The CDC Estimate of Flu Burden
CDC Seasonal Flu Vaccine Primer
CDC explains Live Attenuated Influenza Vaccine
American Academy of Pediatrics Influenza Vaccine Recommendations
American Academy of Family Physicians Influenza Vaccine Recommendations
