People Are Trying To “Boost” Their Johnson & Johnson Vaccine. Experts Are Cautioning Against It.

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With swirling news of the delta variant, "breakthrough COVID," and booster shots, it's natural to wonder if you're really doing everything you can to protect yourself and those around you. And while it's important for fully vaccinated individuals to keep following CDC protocol, wearing masks when needed, and staying alert in a crowd, one thing you shouldn't worry about is whether you're vaccinated enough. Yes, even if you received the single-dose Johnson & Johnson vaccine.
As the delta variant spreads throughout the U.S., some people have started expressing an interest in boosting their Johnson & Johnson dose with a second Pfizer-BioNTech shot for added protection. According to Dr. Mia Taormina, chair of the Department of Infectious Disease at DuPage Medical Group, some are even getting a Pfizer shot without sharing that they're already vaccinated. 
"What's happening here is people are not being forthcoming," Dr. Taormina told The Chicago Tribune. "They've received Johnson & Johnson, they're worried, and they're just showing up at CVS and Walgreens and not even disclosing they received the Johnson & Johnson."
Unlike the mRNA-based Pfizer and Moderna vaccines, the Johnson & Johnson shot uses "more traditional virus-based technology," said Dr. Michael Stevens, associate chair of the Division of Infectious Diseases at the Virginia Commonwealth University School of Medicine. The J&J jab has many benefits: It's easier to store and distribute, it's a single-shot, and most importantly, it offers protection against COVID. But some people still worry that its efficacy rate — 66%, or 72% when it comes to severe cases — is lower than those of Moderna and Pfizer. "I feel like I'm half-vaccinated," one person told the Tribune
But experts, including CDC Director Rochelle Walensky, say that this doesn't mean you should mix vaccines. "Right now, we have no information to suggest that you need a second shot after J&J, even with the delta variant," Walensky said in a June 30 segment on NBC’s Today show
Walensky added that J&J's "sister vaccine," made by AstraZeneca, has proven to be effective against the delta variant in other countries. And in a small study released July 1, Johnson & Johnson announced that the shot "generated strong, persistent activity against the rapidly spreading Delta variant and other highly prevalent SARS-CoV-2 viral variants."
All of this is to say, no, you should not get a second shot if you've already received the Johnson & Johnson vaccine. And even if you want to, it probably isn't a good idea: We just don't have enough research yet, and mixing vaccines could pose unknown health risks. "Until we have better data, it probably is not wise to go and get [additional] vaccines unless it's part of a clinical trial," Dr. Hana Mohammed El Sahly, a molecular virology and microbiology expert at Baylor College of Medicine, told Time
There is a clinical trial underway, though. As Dr. Anthony Fauci said in a June 1 news release, the trial will hopefully yield results on whether it's safe to receive multiple different COVID vaccines. Until then, though, try to find solace in the fact that your vaccine — be it Moderna, Pfizer, or J&J — offers you a lot of protection against the virus.
"If you look at people who are being hospitalized now, it's really been those persons who have not been previously vaccinated," Robert Atmar, a professor of infectious diseases at Baylor College of Medicine, told The Washington Post. "What we need to do, in my opinion, is try and get our populations who aren't vaccinated to accept a vaccine that's readily available, and that will have a much larger impact than trying to roll out a booster strategy at this point."

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