Fact check: False claim 2014 study shows flu nasal spray causes Strep A

The claim: 2014 study shows that flu nasal spray causes strep A

A Dec. 5, 2022, Facebook post (direct link, archived link) shows a screenshot of a 2014 research study titled "Live attenuated influenza vaccine enhances colonization of Streptococcus pneumoniae and Staphylococcus aureus in mice."

"It's the flu nasal spray that's causing strep A," reads the post's caption. "For those that needed a little extra help."

The post generated over 80 shares in less than two months.

Our rating: False

The authors of the study in question told USA TODAY their work in no way proves a link between flu nasal sprays and Strep A. Their study did not even examine Strep A.

Claim misinterprets 2014 study

The 2014 study referenced in the post investigated whether FluMist, a live attenuated influenza vaccine, facilitated bacterial growth and increased the susceptibility to invasive bacterial disease in mice.

Contrary to the post's claim, the study did not investigate Group A Streptococcus, also called Strep A, which causes strep throat, skin infections and acute rheumatic fever, according to Dr. Jon Mccullers, a pediatrics professor at the University of Tennessee who co-authored the study.

Rather, the study investigated Streptococcus pneumoniae, a bacteria that causes pneumonia and meningitis, and Staphylococcus aureus, a bacteria that causes sepsis, endocarditis and pneumonia, according to the Iowa Department of Public Health and the Centers for Disease Control and Prevention.

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"Neither Streptococcus pneumoniae nor Staphylococcus aureus could ever cause Strep A," Dr. Michael Mina, the lead author of the study, told USA TODAY in an email. "All three are entirely distinct organisms with very distinct biology and patterns of infection."

The study also never concluded that flu nasal spray causes any disease for that matter, Dr. Peter Manes, a sinus surgeon and associate professor of surgery at the Yale School of Medicine, told USA TODAY. Rather, it found that while bacterial growth in the upper respiratory tract increased in mice after exposure to FluMist, no increase in invasive disease was detected, according to Mina.

Dr. Keith Klugman, director of the pneumonia program at the Bill & Melinda Gates Foundation who co-authored the study, agreed that the claim misinterprets the study's methods and findings.

"There is no way our paper can be used to support an observation that an increase in serious group A streptococcal infections is caused by an oral flu vaccine," Klugman said.

USA TODAY reached out to the social media users who shared the claim for comment.

Reuters also debunked the claim.

Our fact-check sources:

• Jon McCullers, Jan. 20, Email exchange with USA TODAY

• Peter Manes, Jan. 20, Phone interview with USA TODAY

• Keith Klugman, Jan. 20, Email exchange with USA TODAY

• Michael Mina, Jan. 20-23, Email exchange with USA TODAY

• American Society for Microbiology, Feb. 18, 2014, Live Attenuated Influenza Vaccine Enhances Colonization of Streptococcus pneumoniae and Staphylococcus aureus in Mice

• The Washington Post, Dec. 23, 2022, Strep A: What to know about the usually mild infection tied to at least two U.S. pediatric deaths

• Iowa Department of Public Health, accessed Jan. 23, Streptococcus pneumoniae

• CDC, Jan. 17, 2011, Staphylococcus aureus in Healthcare Settings

• Reuters, Jan. 19, Fact Check-Flu vaccine study unrelated to Group A Strep doesn't show increase of illness

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Our fact-check work is supported in part by a grant from Facebook.

This article originally appeared on USA TODAY: Fact check: False claim 2014 study links flu nasal spray, Strep A

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