A booster shot of the Johnson & Johnson vaccine dramatically increases levels of antibodies to the coronavirus, the company reported Wednesday.
Johnson & Johnson will submit the data to the Food and Drug Administration, which is reviewing similar studies from Pfizer and Moderna. If the agency approves, the Biden administration wants to give booster shots eight months after vaccination.
The Johnson & Johnson vaccine was absent from the government’s original booster plan, announced last week. But with the new data, the company hopes to be part of the first distribution of additional shots, which could happen as early as September.
“We look forward to discussing with public health officials a potential strategy for our Johnson & Johnson Covid-19 vaccine eight months or more after the primary single-dose vaccination,” Dr. Mathai Mammen, the global head of Janssen Research & Development at Johnson & Johnson, said in a statement.
In February, the FDA gave Johnson & Johnson emergency clearance for its one-time vaccine. A clinical trial conducted last fall and winter showed that a single injection had a 72 percent efficacy in preventing symptomatic Covid-19 in U.S. participants. During the trial, none of the vaccinated volunteers were hospitalized or died.
Johnson & Johnson conducted its clinical trial before the Delta variant became widespread, leaving open the question of how well the vaccine worked against the highly contagious form of the virus. But in a study released earlier this month, South African researchers found that a single injection of the Johnson & Johnson vaccine was up to 95 percent effective against death from the Delta variant, and reduced the risk of hospitalization by 71 percent.
In its new study, Johnson & Johnson followed 17 volunteers from last year’s clinical trial. Six months after vaccination, their levels of antibodies had changed little.
That’s different from the pattern we see with the Moderna and Pfizer-BioNTech vaccines. Those shots initially produce higher levels of antibodies, but their levels then drop over the course of several months.
When volunteers in the Johnson & Johnson study were boosted at six months, their antibodies to the coronavirus jumped nine times higher than after the first dose.
Studies on Moderna and Pfizer-BioNTech vaccines found a similar jump in antibody levels. Because the three vaccines have not been tested in a mutual comparison, it is not possible to determine which gives the greatest boost.
Johnson & Johnson said it had submitted a manuscript describing the investigation to the Medrxiv website. It hasn’t been posted there yet.
A number of studies suggest that higher levels of antibodies offer better protection, especially against the Delta variant. But other parts of the immune system, such as T cells, are also important. Thus, these data cannot provide an accurate estimate of how effective the booster injection will be against Covid-19.
“It’s too early to estimate protection,” says Dr. Dan Barouch, a virologist at Beth Israel Deaconess Medical Center in Boston who led some studies for Johnson & Johnson but was not involved in the booster study.
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 that is approved as a single dose. Since November, the company has been conducting a clinical trial to see how much protection people get from two doses, two months apart. That trial is expected to yield results in the coming weeks.
After the volunteers in that trial received the second dose, their antibody levels increased three-fold. The much larger increase in the new booster study is likely because of the longer wait between doses. The six-month break gives the immune system time to develop a more mature response to the coronavirus.
This spring, the distribution of Johnson & Johnson vaccines in the United States was severely hampered by mishandling by a contractor while manufacturing them at a Maryland plant. According to the Centers for Disease Control, only eight percent of vaccinated Americans — or about 14 million people — have received a Johnson & Johnson vaccine.
Since then, the supply of the vaccine in the US has grown. A federal official said the government had enough supplies in reserve to provide boosters to anyone who received a first dose of Johnson & Johnson, should it be allowed.
The news of potential Johnson & Johnson boosters for Americans may sting other countries still waiting for the first doses of the vaccine. South Africa, for example, has ordered 31 million doses of the vaccine, but only two million people there have received it.
In an interview with CNBC last month, a Johnson & Johnson executive said the company aims to produce 500 to 600 million doses worldwide by 2021.
Noah Weiland reporting contributed.
