Johnson & Johnson is evaluating booster shots in clinical trials that enrolled nearly 2,300 participants, but in announcing data that it said support additional vaccination shot, the company only pointed to a study with results from fewer than 20 people.
J&J has been gathering data for boosters from two Phase 1/2a studies begun last year enrolling people previously vaccinated with one shot of the company’s single-dose Covid-19 vaccine. The company announced Wednesday that it has new preliminary data that show a booster generated “a rapid and robust increase in spike-binding antibodies, nine-fold higher than 28 days after the primary single-dose vaccination.”
Furthermore, J&J said the second shot produced “significant increases” in binding antibody responses in study participants 18 to 55 and in those 65 and older who received a lower-dose booster. The company did not specify how many participants were part of the analysis and how many months after the first shot the second dose was administered. The results have not been published and peer reviewed. J&J said that summaries have been submitted to medRxiv, an online archive for preprints.
J&J makes its vaccine from an engineered adenovirus, which is used to deliver the vaccine components to a cell. The company’s vaccine technology, Advac, is the same platform used to develop Janssen’s FDA-approved Ebola vaccine. While the technology has demonstrated it can produce a vaccine, it’s not entirely clear that it will work for boosters. Adenovirus is the virus that causes the common cold. Though J&J’s engineers it in a way that it does not replicate and cause infection, its introduction into the body could trigger the production of antibodies against it. Upon a second injection, those antibodies would recognize the vaccine and attack it. (Chemical & Engineering News has a good explainer here.)
Clinical trial records show that J&J has two placebo-controlled Phase 1/2 studies evaluating boosters given at different dosing schedules. The first clinical trial enrolled 1,085 adults split into five groups. Following the initial vaccination, the different dosing intervals being tested are two, six, eight, 12, 14, and 26 months. The group evaluating participants 65 and older is testing a single dose, as well as two doses given eight weeks apart.
The second Phase 1/2 study enrolled 1,210 participants split into 13 different groups. Ten of the groups will receive the second vaccination after four months; three additional groups will be dosed with a second vaccination after six months. In this study, the initial vaccination was either a single shot or two shots, given 28 days or eight weeks apart. Three groups will be given a single dose.
The only data that J&J points to are from a sub-study—one of the groups from one of the two Phase 1/2a tests of its vaccine—published in the New England Journal of Medicine last month. That sub-study evaluated immune responses in 20 people eight months after the initial vaccination with either one or two doses; five were given a placebo. Antibody and T-cell responses were measured at eight months after a single shot (10 participants) or six months after the two-shot regimen (the other 10 participants).
In three people, antibody responses increased sharply over the eight months. One had a breakthrough infection and the other two received a messenger RNA vaccine. Excluding those three people, the study reported that antibody levels were relatively stable during the eight-month period.
The study appears to support the durability of the J&J vaccine at the eight-month mark, but it’s not clear that these results from a small sample support a booster shot. The study authors wrote that they observed an expansion of neutralizing antibody breadth at eight months, including against the delta variant as well as two variants of concern, “which suggests maturation of B-cell responses even without further boosting.”
Now, J&J is saying that its data (which it has not yet disclosed) support boosters. And with these results, Mathai Mammen, global head of research and development at Johnson & Johnson subsidiary Janssen, said that the company plans to speak with regulators about a booster shot.
“We have established that a single shot of our Covid-19 vaccine generates strong and robust immune responses that are durable and persistent through eight months,” Mammen said in a prepared statement. “With these new data, we also see that a booster dose of the Johnson & Johnson Covid-19 vaccine further increases antibody responses among study participants who had previously received our vaccine. We look forward to discussing with public health officials a potential strategy for our Johnson & Johnson COVID-19 vaccine, boosting eight months or longer after the primary single-dose vaccination.”
Last week, federal health officials announced a plan to begin offering booster shots in September for those eight months past the second shot of a two-dose messenger RNA vaccines from either Moderna or Pfizer/BioNTech. At the time, U.S. Surgeon General Vivek Murthy said that officials were still awaiting additional J&J data about boosters.
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