- A booster shot of Johnson & Johnson's coronavirus vaccine administered after six months may spark a significantly higher immune response than what's observed after one dose, the company reported Wednesday.
- Interim findings from two early stage studies show that the booster increased binding antibody levels by nine times compared to results one month after the first shot. They were announced in a press release, however. J&J says it submitted detailed data to the pre-print server medRxIv on Tuesday, though the study hadn't been published as of early Wednesday.
- J&J's vaccine is the only authorized shot with a one-dose regimen and, so far, the roughly 14 million Americans who have received it have been left off the Biden administration's plan to begin rolling out boosters in September. J&J aims to submit the new results to regulators in the U.S., Europe and elsewhere, however, and begin discussing a booster strategy.
The debate surrounding the need for boosters has largely centered on the two messenger RNA shots from Pfizer and Moderna, each of which have been the most widely used in the U.S. and, as a result, have the most detailed real-world results supporting a potential waning effect against infection and symptomatic disease.
Both Pfizer and Moderna have also touted early results showing boosters administered several months after a two-dose course significantly elevate levels of neutralizing antibodies, which are thought — but not proven — to be a potential marker of a vaccine's potency against the coronavirus. Senior U.S. health officials highlighted those results last week upon announcing plans to roll out booster shots the week of Sept. 20, pending authorizations from the Food and Drug Administration and the Centers for Disease Control and Prevention.
Recipients of J&J's vaccine, however, have thus far been left out of those plans. Though health officials said last week they “anticipate booster shots will likely be needed” for people who have received J&J's vaccine, the drugmaker hadn't yet provided data supporting their potential use. Additionally, a study testing a two-dose regimen is still underway, with results expected within weeks.
With its announcement, though, J&J is signaling an intent to accelerate its booster plans. The company said a booster triggered a “rapid and robust increase” in binding antibodies in 17 study volunteers who had been previously vaccinated. Antibody totals were nine-times higher than what was observed in trial participants four weeks after their first shot, and the increases were seen in both younger adults and people over 65 who received a lower booster dose.
The findings were issued in a press release, however, and don't include key study details. It's unclear, for instance, whether trial participants' immunity had waned or how much an additional shot increased levels of neutralizing antibodies — proteins that, unlike binding antibodies, can disarm a virus and prevent infection. It's also unknown whether the boost will better protect people from infection or illness, or how an additional J&J shot compares with a boost from an mRNA vaccine.
What's more, J&J previously reported in July that levels of neutralizing antibodies among people who received its shot have held for at least eight months. That's different from the mRNA shots, which drive neutralizing antibodies higher, but decline over time.
Nonetheless, U.S. health officials have shown a willingness to administer boosters after eight months for even healthy adults before obtaining definitive proof that they're necessary, wary of waiting too long amid the continued spread of the infectious delta variant. Pfizer and Moderna's shots, for example, continue to largely prevent COVID-19's worst health outcomes, even as levels of protection against infection appear to wane.
"We are concerned that this pattern of decline we're seeing will continue in the months ahead, which could lead to reduced protection against severe disease, hospitalization and death," said Vivek Murthy, the U.S. surgeon general, in a press briefing last week.
J&J plans to discuss a strategy with public health officials for boosting “eight months or longer” after people were first vaccinated, research chief Mathai Mammen said in a statement.