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Which COVID-19 Vaccine Should You Get? The One You Can

All three are 100 percent effective in preventing severe illness and death

Doctor showing two coronavirus vaccine options

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En español | Federal authorization of Johnson & Johnson's COVID vaccine raises new hope for getting more Americans vaccinated sooner than expected. However, because the J&J vaccine has a lower efficacy rate than the two vaccines already in use, Pfizer-BioNTech and Moderna, its authorization also raises questions about which shot to get. The answer, health experts say, is get the one you can get, and get it now.

Don't hold out for a preferred vaccine, says Aaron Richterman, M.D., a fellow in the Division of Infectious Diseases at Penn Medicine in Philadelphia, because the earlier people are vaccinated, the better. “The greatest risk for this infection and exposure to infection is now,” Richterman says. “Any immune protection that you can get as soon as you can is, on balance, going to be the best."

Pfizer-BioNTech and Moderna COVID-19 vaccines — used in the U.S. since December — were shown in clinical trials to be about 95 percent effective in preventing symptomatic COVID-19 after two doses. The J&J vaccine was shown to be 66.1 percent effective in preventing COVID-19 symptoms after one dose in multi-country clinical trials and 72 percent effective among participants in U.S. trials. Health experts note that all three vaccines were shown to be 100 percent effective in preventing hospitalization and death from COVID-19.

"It's important to remember that they're not head-to-head comparisons,” says Amesh Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security in Baltimore. “These are all separate clinical trials that were done in different parts of the world and at different times. Johnson & Johnson [trials] started later, when there was much more community spread going on and you're more likely to get infected.”

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The J&J vaccine is “absolutely a blockbuster in terms of all the things that are really, really important,” Richterman says. “No one who got it was hospitalized.” The only thing suggested by the trials, he adds, is that people vaccinated with the J&J shot are slightly more likely to get COVID-19, but if they do, it will be “a very mild illness … like a mild, cold-like infection we deal with all the time.”

Public health advocates view availability of the J&J one-shot vaccine as an opportunity to more easily vaccinate hard-to-reach people, including migrants and those who are homebound. Northwell Health's House Calls program, which is based in New Hyde Park, New York, and serves about 1,500 patients in the region, plans to start home vaccinations soon. “Johnson & Johnson will make this easier,” says the program's medical director, Karen Anna Abrashkin, M.D. But with patients continuing to get infected with COVID-19, she adds, “We're really ready to use whatever we can get access to. Time is of the essence.”

Christina Ianzito is a Washington, D.C.-based journalist who joined AARP in 2010. She's the travel and books editor for and AARP The Magazine, and also edits and writes health, entertainment and other stories for She received a 2020 Lowell Thomas Award for travel writing.