COVID vaccine: Does Pfizer's coronavirus shot prevent you from infecting others?

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Monday, December 14, 2020
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The Pfizer and Moderna vaccines prevent people from getting very sick with the virus, but do they prevent someone from becoming infected with COVID-19?

CHICAGO (WLS) -- The Pfizer COVID-19 vaccine provides 95% protection from virus, but can you still be infected and pass the virus to others after getting a shot?

RELATED: First COVID-19 vaccines arrive in Illinois

Vaccine shipments arriving in Illinois and around the country are visual reminders that the end may be near. But, what exactly does the vaccine do?

"What the study does when it follows its subjects - these studies are about 40,000 people - it's whether you develop symptoms," said Dr. Alfredo Mena Lora, with St. Anthony Hospital Infection Prevention.

So far, what is known about the Pfizer and Moderna vaccines is that they prevent people from getting very sick with the virus, but it may not prevent someone from becoming infected with COVID-19. Early phases of vaccine research are only designed to test efficacy and safety.

"As time goes on, we will collect more information and that's why these studies are two years, we need to collect more data over that longer period of time," said Dr. Richard Novak, an infectious disease doctor for University of Illinois - Chicago.

Besides prevention from infection, Infectious disease doctors overseeing vaccine trials said what remains to be answered is how long the vaccine will last.

"We are not 100% sure, is it possible we need some sort of booster in 6 months or a year?" Dr. Mena-Lora said.

"Those are questions that have to be answered," Dr. Novak said. "We have not been studying children. They're just now starting trials in children to make sure they are efficacious in kids."

So until the general public is vaccinated and some of the unknowns are answered, doctors can't stress enough how important it is to continue following COVID-19 protocols.

See complete coverage of the COVID-19 vaccine at