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By Jessica Rendall (Source: CNET Oct. 18, 2021)

An advisory panel to the US Food and Drug Administration unanimously voted Friday to recommend boosters of Johnson & Johnson's COVID-19 vaccine, at least two months after the one-dose vaccine. The panel wants the FDA to authorize a second shot for all Johnson & Johnson recipients, which is broader than the recommendations the panel made for who should get a booster dose of Pfizer or Moderna, with some members arguing Johnson & Johnson should've been a two-dose vaccine from the beginning. Johnson & Johnson's vaccine is authorized for people age 18 and older. Provided by Once given the official go-ahead by the FDA, an advisory committee to the US Centers for Disease Control and Prevention will meet to decide how to roll out the boosters. It's also increasingly possible that health officials may give the green light for Americans to mix COVID-19 vaccines, meaning that Johnson & Johnson recipients would be able to get a shot of Moderna or Pfizer as a booster instead. But no vote or recommendation on mixing COVID-19 vaccines has taken place yet. Fewer people have gotten Johnson & Johnson's one-dose vaccine than Pfizer or Moderna: About 15 million people have been vaccinated with J&J, according to the CDC, a small number compared with those vaccinated with Pfizer or Moderna. This is partly because it was available in the US later than both mRNA vaccines, experienced production issues that resulted in millions of wasted doses and was paused briefly in April after concerns over a link to a rare but serious blood clotting disorder that isn't seen with the mRNA vaccines. Those who got the one-dose J&J vaccine -- including immunocompromised people -- were initially left out of the country's booster shot plans because of a lack of data on the one-dose vaccine. (The booster rollout in general is a controversial one -- members of the World Health Organization have called on countries such as the US to slow the process of giving booster doses to people who are already vaccinated because much of the world remains unvaccinated against COVID-19. As few as 2.7% of people in low-income countries have had a coronavirus vaccine, according to Our World in Data.) While health agencies continue to iron out booster recommendations, here's what we know now about second shots of Johnson & Johnson. 

I'm immunocompromised and got the Johnson & Johnson shot. Can I get an mRNA booster? 

An extra dose of an mRNA vaccine (Moderna or Pfizer) is only recommended by the CDC, and authorized by the FDA, for people who got fully vaccinated with either of those two vaccines -- it is not recommended for immunocompromised people who received a J&J shot. This is because, according to the CDC, "There is not enough data at this time to determine whether immunocompromised people who received the Johnson & Johnson's Janssen COVID-19 vaccine also have an improved antibody response following an additional dose of the same vaccine." That is, fewer people got J&J, so the available data on a third dose's benefits for immunocompromised folks centers on those who got Pfizer or Moderna shots. However, once the FDA accepts the advisory committee's recommendation on Johnson & Johnson boosters, as it's expected to do, every J&J recipient should be able to get a booster. There have been many experts who disagree with the CDC and FDA's stance on waiting for more data when it comes to those who are more vulnerable to severe COVID-19 and who received J&J. Research shows that viral vector vaccines like J&J and AstraZeneca are likely less effective than mRNA vaccines. This was confirmed at the recent FDA committee meeting, where members voted to recommend boosters of Johnson & Johnson based on less-than-perfect data provided to and reviewed by the FDA. In an editorial for the Washington Post on why public health agencies should allow J&J recipients to receive a dose of mRNA vaccine, CNN medical analyst Dr. Leana Wen wrote: "This isn't a one-size-fits-all recommendation, but rather an individualized decision based on people's medical circumstances and exposures. "While a healthy younger person is probably adequately protected with Johnson & Johnson, someone who is severely immunocompromised is "likely not optimally protected by the J&J," Wen said, and the unknown risks of mixing vaccine types is "almost certainly" outweighed by the risks of severe COVID-19. There may be some local exceptions: For example, if you live in San Francisco and received J&J, you can get a dose of Pfizer or Moderna. However, the city's health department stresses this is not a recommendation or change in policy, but an "accommodation" for Johnson & Johnson recipients who've asked their physicians about receiving a dose of mRNA vaccine. If or when boosters become a reality in the US, it's unclear how that will change the CDC's definition of "fully vaccinated," or how that will vary based on the type of vaccine you received. 

Will everyone who got J&J eventually need a booster? When? 

The FDA committee's vote to recommend boosters for all J&J recipients was a strong statement (booster doses of Pfizer or Moderna are only authorized or recommended for some adults who received the mRNA vaccines), and the FDA itself is expected to follow the committee's decision. When the advisory panel voted, they determined that one dose of Johnson & Johnson may not be sufficient and people who received the one-dose vaccine should be able to get a second dose. If authorized, it will be up to the CDC to recommend how people seek out booster shots if they received Johnson & Johnson, or if the agency will issue a strong recommendation for some J&J recipients while simply saying other people who got J&J "may" get a booster. For example, the CDC says now that Pfizer recipients age 65 and older, and people with certain health conditions "should" get a third shot, while other Pfizer recipients who are at risk because of their job or are younger adults with health conditions "may" get a booster if they choose.

When a booster for J&J becomes available, will it be another dose of J&J or a dose of mRNA vaccine?

The FDA is expected to authorize a booster dose of Johnson & Johnson, meaning a second dose of that vaccine is likely on the table for everyone who received it. However, some experts believe that J&J recipients may benefit from receiving a different vaccine, as seen in preliminary data on "mixing and matching" COVID-19 vaccines, which was discussed at the FDA committee meeting Friday. While many public health experts believe this mixed approach will be safe, researchers and scientists need to conclude that the benefits of receiving two types of coronavirus vaccine outweigh any potential risks before they authorize it or recommend people do it. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.  

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