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If you received the Johnson & Johnson vaccine as your first COVID vaccine, a booster dose of the Moderna or Pfizer-BioNTech vaccine could apparently produce a stronger immune response than a second dose of the J&J vaccine. That’s the conclusion of a long-awaited study released Wednesday.
And if you started with Pfizer or Moderna, it probably doesn’t matter much, research suggests, as long as you get one of the two mRNA vaccines as a booster.
The study, which was sponsored by the National Institutes of Health, involved 458 volunteers. They were divided into nine groups with about 50 volunteers in each group. Those who initially received the two-dose Moderna vaccine received another injection of Moderna, an injection of Pfizer, or an injection of Johnson & Johnson as a booster four to six months after their primary vaccination.
People who received the two-dose Pfizer vaccine received either another Pfizer vaccine or a Moderna or J&J booster. And people who received the J&J vaccine as a single injection received either another J&J injection or a Moderna or Pfizer booster.
The researchers then measured the antibody levels in all of these people two weeks and four weeks after the booster. The results have been very interesting.
People who received the Moderna vaccine for their original injections and Moderna for their booster seem to have had the best immune response, followed by those who received Moderna-boosted Pfizer, then Pfizer-boosted Moderna – although the response increased. Immune with vaccine mRNA was probably too small to really make a difference in protection in most groups.
The most important finding suggests that people who initially received the J&J vaccine seem to have had the best response if they were given Pfizer or Moderna as a booster.
In an email to NPR, Nathaniel Landau, a microbiologist at New York University’s Grossman School of Medicine, said the results show that receiving a J&J boost after the initial one-time vaccination is “not so good “than to receive one of the other vaccines as a booster. The antibody levels of people in these groups increased 10 to 20 times more than those of people who received another injection of J&J.
And that increase in antibodies is probably large enough to make a difference in improving protection, scientists say. It is not clear how much better – this study was not large enough to determine how less likely people who were subsequently infected with the coronavirus were to get sick – or how sick they got. But, based on other research, this kind of difference in antibody response is probably enough to offer greater protection.
There are a few caveats to this study that make it a bit difficult to know how to interpret the data. First, the researchers tested full doses of all vaccines – not the half dose for which Moderna is seeking clearance in its recall.
Additionally, researchers measured antibody levels two and four weeks after the booster. It is therefore possible that the antibody levels of a J&J booster will continue to increase over time. And scientists assume that higher antibody levels translate into greater protection. This is probably true, but other factors may also play a role, such as the responses of other parts of the immune system.
The researchers also claim that their study was not designed to compare the different responses between different booster regimens and that the dataset is not large enough to draw conclusions about one versus the other. Finally, the study results were published without peer review on the medRxiv preprint server.
The results are not a complete surprise. Something similar was seen in the UK, when people who received the AstraZeneca vaccine – which is similar to the J&J vaccine – received boosters.
Data from the NIH study will be reviewed by Food and Drug Administration advisers later this week in a meeting to review Moderna and J&J’s requests to allow booster doses of their vaccines.
The FDA has already authorized a booster dose of the Pfizer-BioNTech vaccine for anyone over the age of 65, or whose health, occupation or living situation puts them at risk of serious illness.