Fact check: Vaccines protect against contracting, spreading COVID-19

The claim: The COVID-19 vaccine doesn't stop you from getting or spreading the virus, so it can't protect others

More than 70% of adults in the U.S. are fully vaccinated against COVID-19. Children started receiving their vaccines in early November, and booster shots may be on the way for most Americans.

COVID-19 cases dropped after the vaccines were introduced in the spring. But on Facebook, some still doubt whether the shots work.

"Since the (vaccine) doesn't stop you from getting it or spreading it... How ...are you actually protecting others," reads text in a Nov. 13 post from a page called The Lion's Roar.

The post accumulated more than 69,000 shares within four days. Similar claims have racked up tens of thousands of interactions on Facebook and Instagram over the past month, according to CrowdTangle, a social media insights tool.

In clinical trials, all three vaccines authorized in the U.S. were found to be safe and effective at preventing severe COVID-19 cases. Since then, public health officials have acknowledged the shots aren't 100% effective at preventing infection – and research suggests immunity wanes over time.

But that doesn't mean the COVID-19 vaccines are worthless. Experts and public health officials say they do protect people from getting infected and spreading the virus.

Fact check: COVID-19 vaccine protects both the person vaccinated and those around them

"This is false information," Akiko Iwasaki, a professor of immunobiology and molecular, cellular and developmental biology at Yale University, said in an email. "Vaccines provide significant protection from 'getting it' – infection – and 'spreading it' – transmission – even against the delta variant."

USA TODAY reached out to The Lion's Roar for comment.

Vaccines decrease chances of infection, transmission

All three COVID-19 vaccines authorized in the U.S. were designed to prevent severe infection, hospitalization and death. But experts and public health officials say the shots also protect people from contracting and spreading the virus.

"What we know is that individuals who are vaccinated are much less likely to be infected therefore much less likely to spread the virus," Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, said in an email.

Laryah Wakefield, 10, looks on as she receives a COVID-19 vaccine at Carter Traditional Elementary School during a vaccine drive Saturday morning. Nov. 13, 2021
Laryah Wakefield, 10, looks on as she receives a COVID-19 vaccine at Carter Traditional Elementary School during a vaccine drive Saturday morning. Nov. 13, 2021

Data from clinical trials indicate the vaccines from Pfizer-BioNTech and Moderna are about 95% effective at preventing symptomatic COVID-19 infections. Johnson & Johnson's shot was found to be about 72% effective at preventing moderate to severe disease. (That number is lower partly because of the higher volume of COVID-19 cases in the general population during the trial period.)

The vaccine rollout has affirmed those findings.

Fully vaccinated people made up about 9% of reported COVID-19 deaths in 13 U.S. jurisdictions between April and July, according to the Centers for Disease Control and Prevention. CDC studies have also shown unvaccinated people are 10 times more likely to be hospitalized with COVID-19.

Fact check: Infected with COVID-19 in the past? You still need the vaccine, experts say

The agency says on its website that, while breakthrough infections are possible, "most people who get COVID-19 are unvaccinated." Experts told USA TODAY the shots provide considerable protection against infection and transmission.

"Yes, it is true that vaccinated individuals can also be infected by and spread SARS-CoV-2 to others," Shweta Bansal, an associate professor of biology at Georgetown University, said in an email. "However, the evidence is crystal clear that risk of transmission for a vaccinated individual is significantly lower than for an unvaccinated individual."

Bansal pointed to data from the United Kingdom, which shows the COVID-19 vaccines reduce the chances of getting infected by 50%-75%. A preprint study, also conducted in the U.K., found that two doses of the Pfizer vaccine are 80% effective against preventing all infections with the delta coronavirus variant.

Data on how COVID-19 vaccination affects transmission is more complicated, but still promising.

"Within the breakthrough infections with delta, the viral load is similar to those who became infected and were unvaccinated," Iwasaki said. "This may be the source of confusion about the claim that vaccines don’t stop you from spreading the virus."

Research indicates vaccinated individuals who get infected with COVID-19 can transmit the virus at a similar level as unvaccinated people. But data also show they get better faster than the unvaccinated, meaning they may be less likely to spread the virus to others. Several studies awaiting peer review back that up.

And of course, the vaccinated are far less like to contract COVID-19 in the first place, as previously noted.

More: Want enhanced clarity on the news? Join text chat with USA TODAY's expert fact-checkers.

Public health experts are worried that some people who received the COVID-19 vaccine months ago may see their protection diminish over time. But that's not out of the ordinary for a vaccine, and booster shots have been shown to drastically increase protection against the virus.

"The COVID-19 vaccines incontrovertibly decrease (the) spread of the virus," Adalja said. "Just because they are not 100% does not mean it is nothing."

Our rating: False

Based on our research, we rate FALSE the claim that the COVID-19 vaccine doesn't stop you from getting or spreading the virus, so it can't protect others. While vaccinated individuals can get COVID-19, experts and public health officials say they are less likely to contract the virus than unvaccinated people. That means they're also less likely to spread the virus to others. When vaccinated people do get sick, the chances of severe illness, hospitalization or death are low. Research indicates they also get better faster than their unvaccinated counterparts.

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This article originally appeared on USA TODAY: Fact check: COVID-19 vaccines protect against infection, transmission