Key threat to unvaccinated people is other unvaccinated people

A counterintuitive claim about COVID-19 argues that people who are not vaccinated actually face a bigger threat from vaccinated people than from the unvaccinated. 

The Instagram post says:

"Be careful of vaccinated people spreading COVID to you! They are a threat to the unvaccinated. Less severe symptoms means they may not know they have it and then may spread it to you, putting your life at risk They are the real threat. The ones who are spreading it unknowingly."

The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

Unvaccinated people can become infected by vaccinated people who get a breakthrough case of COVID-19.

But the greater threat to unvaccinated people is other unvaccinated people.

The claim "is wrong — dangerously so," said virologist Robert Garry, professor at the Tulane University School of Medicine.

"Unvaccinated people are most likely to spread to other unvaccinated people," he said. The next most likely pattern is unvaccinated people spreading to vaccinated people, he said. 

"Third is vaccinated spreading to unvaccinated," he said, "but this is going to be much rarer than the first two scenarios. Least likely is vaccinated to vaccinated."

In late July, the federal Centers for Disease Control and Prevention reverted to previous guidance and recommended that everyone, including fully vaccinated people, wear masks in indoor public spaces in areas where spread of COVID-19 was high. 

The guidance was updated "to ensure the vaccinated public would not unknowingly transmit virus to others." 

The update was based on the discovery that infection from the highly contagious delta variant resulted in similarly high viral loads in vaccinated as well as unvaccinated people. In other words, unlike with other variants, vaccinated people could get breakthrough cases of COVID-19 and transmit the virus.

But this was a precaution to help prevent the spread.

The Instagram claim ignores the fact that the unvaccinated are more likely to become infected, and to become seriously ill. And like vaccinated people, they can also be asymptomatic and spread the disease unknowingly.

They are more likely to spread the disease. A study led by University of Oxford researchers that was posted Oct. 15 found among cases in England that vaccinated people who get breakthrough infections are less likely than unvaccinated people to infect others with the delta variant. 

A study in China published in August also found that the unvaccinated were more likely to spread infection. A third study, done in Singapore and published in July, found that vaccination is associated with faster decline in viral load, a possible indicator of declining infectiousness. None of the studies had been peer reviewed.

Unvaccinated people lack protection against the disease. The CDC reported in September that the range of COVID-19 vaccine effectiveness remained high in the United States, even though it had decreased since the onset in late June of the delta variant, which the agency said is more than twice as contagious as previous variants. The effectiveness against infection ranged from 39% to 84%, and against hospitalization ranged from 75% to 95%. 

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A study in the Netherlands published in August said that the COVID-19 vaccines not only protect the vaccinated person, "but also offer protection against transmission to close contacts."

Unvaccinated people face greater risk of hospitalization and death. In September, the CDC analyzed vaccine effectiveness across 13 U.S. jurisdictions from April 4 to July 17 and matched that data to vaccine registries from those areas. It found that after delta became dominant, unvaccinated people were five times more likely to be infected than fully vaccinated people, and more than 10 times more likely to be hospitalized or die. 

Meanwhile, as of Oct. 18, more than 189 million people in the United States had been fully vaccinated against COVID-19, according to the latest CDC statistics. Of them, 41,127 got COVID-19 and were hospitalized or died. That is 0.021%. About 85% of the deaths and 66% of the hospitalizations were among those 65 or older.

Unvaccinated people are most likely to be infected by other unvaccinated people because the unvaccinated "are far more likely to get COVID, and when they get it, they are infectious for a significantly longer time than vaccinated people are," said Dr. Robert Wachter, professor and chair of the Department of Medicine at the University of California, San Francisco. 

With the delta variant and over time, the vaccine effectiveness wanes a bit, Wachter said, "but vaccinated people remain far less likely to have and to spread infection."

An Instagram post claimed that, with COVID-19, vaccinated people "are the real threat to" unvaccinated people.

Unvaccinated people can get COVID-19 from vaccinated people who get breakthrough infections. 

But the greater threat to the unvaccinated is other unvaccinated people. Unvaccinated people are more likely than the vaccinated to get COVID-19, more likely to spread it, and much more likely to become seriously ill or die. 

We rate the post False.

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