Johnson & Johnson Says Extra Shot Gives Promising Immune Boost

Those who got the one-shot Covid-19 vaccine could benefit from a booster after eight months, according to the company

Blue gloved hand holds a small glass vial of Johnson and Johnson covid-19 vaccine
Early trials show a second dose of the J&J Covid-19 vaccine after six months later provides a promising antibody response. Mohammad Shahhosseini via Unsplash

People who received the single-dose Johnson & Johnson Covid-19 vaccine may benefit from a second booster dose, the company said in a press release on August 25. Study participants given a second dose after six months showed antibody levels nine times higher than 28 days after their original shot. The extra jab could serve as a much-needed immune boost as vaccine efficacy begins to wane and the Delta variant surges across the country.

The Johnson & Johnson booster "appears to be safe, and boosts immune responses substantially," says Harvard virologist Dan Barouch to Sony Salzman for ABC News. "It’s some of the data people have been asking for and waiting for and wanted to see.”

The combined rise of the high-contagious Delta variant and the waning efficacy of Covid-19 vaccines has put mounting pressure on officials to consider booster shots. Earlier this month, the Biden Administration announced that some immunocompromised Americans could start receiving a booster of the Pfizer-BioNTech shot as early as September. Only those 18 years and older who got the mRNA-based Pfizer or Moderna vaccines will be eligible for the Pfizer booster dose. For many of the 14 million people who got the Johnson & Johnson vaccince since its emergency authorization in February, the announcement is welcome news.

The dramatic spike in antibodies is promising and Johnson & Johnson says it plans to submit its research to the Food and Drug Administration in the hopes their booster is authorized, report NPR's Joe Hernandez, Joe Neel and Rob Stein. Evidence of the booster’s antibody response is promising—but early. Per NPR, the data has not yet been peer-reviewed or published in a scientific journal, and the study involved just 17 participants. Though participants in the trial were given the booster six months after their original dose, the company is recommending boosters after eight months.

"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," said Mathai Mammen, a spokesperson for Johnson & Johnson, in a 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."

More research is needed to understand the link between antibody levels and protection from infection in the real world, report the New York Times’ Carl Zimmer and Sharon LaFraniere. Because no studies have compared the efficacy of each booster, it’s challenging to determine which offers the most protection from Covid-19.

“It’s too early to guesstimate protection,” says Barouch to the New York Times.

Even as the spread of the Delta variant and waning vaccine potency leads to rare breakthrough infections, the overwhelming majority of people hospitalized and dying from SARS-CoV-2 are unvaccinated. The World Health Organization has asked wealthier countries like the United States to delay booster rollouts as many other countries struggle with the first round of vaccinations.