Second Dose of J. & J. Vaccine Gives Strong Boost, Company Reports

Studies on Moderna and Pfizer-BioNTech vaccines found a comparable jump in antibody levels. Because the three vaccines were not tested in a head-to-head comparison, it’s not possible to determine which one provides the biggest boost.

Johnson Johnson said that it had submitted a manuscript describing the research to the website Medrxiv. It has not been posted there yet.

A number of studies suggest that higher levels of antibodies provide better protection, especially against the Delta variant. But other parts of the immune system, such as T cells, are also important. So this data cannot give a precise estimate of how effective the booster shot will be against Covid-19.

“It’s too early to guesstimate protection,” said Dr. Dan Barouch, a virologist at Beth Israel Deaconess Medical Center in Boston, who has led some studies for Johnson Johnson but was not involved in the booster trial.

Aside from antibodies, Johnson Johnson researchers also found that the booster increased the body’s supply of immune cells that can attack cells infected with the coronavirus. Those results are still being prepared for publication.

The Johnson Johnson vaccine is the only shot in the United States or Europe authorized as a single dose. Since November, the company has been running a clinical trial to look at how much protection people get from two doses, two months apart. That trial is expected to deliver results in the next few weeks.

After the volunteers in that trial received the second dose, their antibody levels rose by a factor of three. The much bigger increase in the new booster study is likely because of the longer wait between doses. The six-month pause gives the immune system time to develop a more mature response to the coronavirus.

Article source: https://www.nytimes.com/2021/08/25/health/johnson-booster-shot.html