Can Getting the COVID Vaccine Make You Contagious to Others?

None of the COVID vaccines currently rolling out across the U.S. will result in a person being contagious for the disease itself, experts say.

With multiple vaccines now approved for use, some people have turned to the internet for answers. Over the past day, there was a rise in searches from Americans asking if COVID can be contracted from a person who has just received a vaccine.

Searches included "Can you get COVID from someone who has just been vaccinated" and "Can you catch COVID from someone who just had the vaccine?"

The underlying suggestion on some of these queries logged by the search engine giant was that a dose of the vaccine could somehow make that person more likely to spread SARS-CoV-2, which is the name of the virus known to cause COVID disease.

Such an assumption could be based around the fact other vaccines use a virus itself to prompt the body to start an immune response. But health experts, and the companies making the COVID vaccines, are clear: That's not how these vaccines work.

The Centers for Disease Control and Prevention (CDC) has said COVID vaccines will not make a person sick with the disease. Crucially, none of the three approved vaccines contain the live virus that causes COVID, only instructions that teach our body how to
"recognize and fight" future infections of SARS-CoV-2, and build up immunity.

It says: "Sometimes this process can cause symptoms, such as fever. These symptoms are normal and are a sign that the body is building protection against the virus

"It typically takes a few weeks for the body to build immunity (protection against the virus that causes COVID after vaccination. That means it's possible a person could be infected with the virus that causes COVID just before or just after vaccination and still get sick. This is because the vaccine has not had enough time to provide protection."

There are three vaccines authorized for use in the U.S., from Pfizer-BioNTech, Moderna and Janssen/Johnson & Johnson. As of March 17, at least 113,037,627 doses had been administered and roughly 12 percent of the U.S. was fully vaccinated.

The Pfizer-BioNTech and the Moderna vaccines use a technique known as messenger RNA (mRNA), a genetic material that teaches your body how to make proteins. In this case, it is a "spike protein" that is found on the surface of the COVID virus.

After a vaccine shot, a person's immune cells start displaying the protein on the surface, which then forces the body to create antibodies—which combat future infection.

The CDC says on its website: "mRNA vaccines do not use the live virus that causes COVID. They do not affect or interact with our DNA in any way. mRNA never enters the nucleus of the cell, which is where our DNA (genetic material) is kept. The cell breaks down and gets rid of the mRNA soon after it is finished using the instructions."

The Janssen/Johnson & Johnson version is a similar "vector vaccine" that is based on proving instructions using genetic material from the virus—but not the virus itself. In all cases, people will not be contagious because of a COVID vaccine dosage.

People who are currently sick with the novel coronavirus cannot receive a vaccine for the disease while ill, either with or without symptoms, the CDC has said.

The World Health Organization (WHO) says infected people can be contagious and are believed to be most infectious roughly two days before the onset of symptoms. "People who develop severe disease can be infectious for longer," it previously warned.

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