J&J COVID-19 booster shot generates 'robust' antibody response, company says

NEW BRUNSWICK, N.J. - Johnson & Johnson said Wednesday that new data support a booster dose of its COVID-19 vaccine after studies showed antibodies levels were nine times higher than after the original dose of its vaccine.

The company said in a release that interim data showed that a booster dose "generated a rapid and robust increase in spike-binding antibodies, nine-fold higher than 28 days after the primary single-dose vaccination." 

A prior study published in July also found that people vaccinated with the Johnson & Johnson vaccine still had "strong and stable" antibody responses eight months later.

"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 Dr. Mathai Mammen, global head of Janssen research & development. 

Mammen added that the new data show "a booster dose of the Johnson & Johnson COVID-19 vaccine further increases antibody responses among study participants who had previously received our vaccine."

J&J’s new research comes amid the surging delta variant and signs that the vaccines’ effectiveness is slipping. The U.S. Food and Drug Administration is already allowing the emergency use of a third dose of either the Pfizer or Moderna vaccine for people with severely weakened immune systems, such as organ transplant recipients and cancer patients who don’t respond as strongly to the usual two shots. 

For everyone else who got those vaccinations, the Biden administration is planning ahead for booster shots eight months after the second dose — if the FDA and Centers for Disease Control and Prevention agree. The doses could begin the week of Sept. 20.

U.S. health officials have said that the 14 million Americans who received the J&J shot will also probably need the extra dose at some point, but data is still being collected in order to decide.

The J&J vaccine rollout didn't start until March, several months after Pfizer and Moderna vaccinations began, resulting in the delayed data collection. The J&J shot is also made differently, and there's more data about how the mRNA Pfizer and Moderna vaccines fare against delta because they’re more widely used in countries where the delta variant struck.

In the meantime, all the vaccines currently being administered in the U.S. — including the J&J vaccine — are still doing their job of preventing hospitalizations and deaths from COVID-19, researchers say. But Pfizer CEO Albert Bourla said this week that the company believes a coronavirus variant able to escape the protection of available vaccines will likely one day emerge.

Officials said that before any booster program starts up, both the FDA and a CDC advisory panel would need to evaluate the safety and effectiveness of an extra dose.

"We have a responsibility to give the maximum amount of protection," President Joe Biden said last week at the White House. He added that extra doses are also "the best way to protect ourselves from new variants that could arise."

J&J said it was working with federal health officials, including the FDA, CDC and the European Medicines Agency, to discuss a potential booster shot strategy "eight months or longer after the primary single-dose vaccination."

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This story was reported from Cincinnati. The Associated Press contributed.