Fact check: COVID-19 vaccines primarily designed to prevent serious illness, death

·5 min read

The claim: CDC director says vaccines can’t prevent transmission of COVID-19

As the omicron variant surges across the world and the United States logs case numbers near and over 1 million per day, the virus is prompting scientists to develop new treatments and government officials to fight to curb the spread.

While the Biden administration continues to urge Americans to get vaccinated, a Jan. 10 Facebook post claims that Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said vaccines can’t prevent COVID-19 transmission. Other sites have shared the same claim, linking Walensky’s words back to an interview with CNN in August 2021.

“Our vaccines are working exceptionally well," Walensky said to CNN's Wolf Blitzer in the interview. "They continue to work well for delta, with regard to severe illness and death – they prevent it. But what they can't do anymore is prevent transmission."

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Though Walensky did say these words on CNN, the original interview was aired in early August, not recently. And while it's true vaccines can't entirely halt transmission, experts say they do reduce it – and reduce the chances of hospitalization and death – as USA TODAY previously reported.

USA TODAY reached out to the original poster of the claim for comment.

Various websites have written about the same claim, amassing thousands of interactions on Facebook.

Vaccine effects depend on several factors

In an email, Walensky spokesperson Kathleen Conley wrote that in August 2021 – when the interview originally ran – the delta variant was the dominant variant in the United States.

Experts at that time said it was clear the vaccines provided protection.

"Vaccines provide significant protection from 'getting it' – infection – and 'spreading it' – transmission – even against the delta variant," Akiko Iwasaki, a professor of immunobiology and molecular, cellular and developmental biology at Yale University, told USA TODAY in November.

However, Conley noted data did show vaccines were “less effective at preventing infections and transmission with Delta than with previous other variants.” Omicron has proven even more difficult to contain.

While mRNA vaccines – produced by Pfizer and Moderna – continue to offer some level of protection against transmission of omicron, other vaccines – such as Johnson & Johnson, Sinopharm and AstraZeneca – offer “almost no defense," according to a Dec. 19, 2021, report by the New York Times.

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Other factors beyond variant type, vaccination type and booster status can also influence whether or not a person contracts COVID-19.

Dr. David Dowdy, associate professor of epidemiology at Johns Hopkins Bloomberg School of Public Health, said it's difficult to succinctly explain the vaccines’ nuanced effects on transmission.

A vaccine might protect you from a passing interaction with someone at a grocery store, but it may not prevent infection from someone you live with and share air with for several hours a day.

“It gets very easy to misconstrue,” Dowdy said. “If someone asks, do vaccines prevent infection, and you have to give a yes or no answer, then the answer is no, they’re not a perfect blockade. But do the vaccines offer some protection against infection? The answer is yes.”

The Biden administration continues to urge Americans to get vaccinated as omicron spreads.
The Biden administration continues to urge Americans to get vaccinated as omicron spreads.

Vaccines still protect against serious disease

While vaccinations don’t offer perfect protection against the transmission of COVID-19, experts still urge people to get vaccinated.

According to Conley, COVID-19 vaccination remains effective against hospitalization and death caused by the virus. Getting a booster, she added, further decreases these risks, and the CDC continues to recommend that Americans receive vaccines and boosters.

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Dr. Chris Beyrer, professor of public health and human rights at the Johns Hopkins Bloomberg School of Public Health, said both the mRNA and J&J vaccines were never designed to prevent infection entirely.

It’s “very hard”, he said, to prevent infection via an injected vaccine when you’re dealing with a virus that enters the body through the nose and mouth. Instead, the vaccine trials were designed to study reduction in serious illness, hospitalization and death. All three vaccines were highly effective by this measure, Beyrer said.

“People who say, well, why would I take it if it doesn’t prevent me from getting infected?” Beyrer said. “You have to remember that having a COVID-19 infection can be everything from completely asymptomatic ... to a head-cold-like symptoms or full flu-like symptoms, all the way to death. So what the vaccines are doing is really dramatically increasing the likelihood that you will have mild infection. And that’s incredibly important.”

A CDC study released Jan. 21 showed booster shots of the Pfizer-BioNTech and Moderna vaccines were 90% effective at preventing hospitalizations from the omicron variant.

Our rating: Missing context

Because it can be misleading without additional information, we rate MISSING CONTEXT the claim that the CDC director says vaccines can’t prevent transmission of COVID-19. While vaccines do not offer 100% protection against COVID-19 infection, they can still partially defend against infection. Vaccines remain effective at protecting from COVID-19-caused serious illness, hospitalization and death.

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This article originally appeared on USA TODAY: Fact check: Vaccines limit serious illness and death from COVID-19