Why does the Johnson & Johnson vaccine work against variants? A new study suggests an answer

Gerald McDavitt, 81, a Veteran of the United States Army Corps of Engineers, held his CDC Vaccine Card in his shirt pocket after being inoculated with the Johnson & Johnson COVID-19 Janssen vaccine at his home in Boston.JOSEPH PREZIOSO/AFP via Getty Images

New research suggests that Johnson & Johnson’s single-dose COVID-19 vaccine provides protection against worrisome virus variants — but perhaps not for the reasons researchers originally thought.

The findings, published Wednesday in the peer-reviewed journal Nature, come from a 25-person study at Beth Israel Deaconess Medical Center in Boston, which looked at immune responses to variants first discovered in Brazil, South Africa, Southern California, and the United Kingdom. Twenty people in the study received the Johnson & Johnson vaccine, five received a placebo, and their blood samples were analyzed 57 and 71 days days after their shot.

Beth Israel codeveloped the Johnson & Johnson vaccine alongside the New Jersey-based pharmaceutical giant. The vaccine was authorized for use in the US in late February.

Dr. Dan Barouch, who runs the virology center at Beth Israel and led the study, said one of the reasons the variants pose a threat is because they are thought to evade the disease-fighting antibodies that existing COVID-19 vaccines are designed to produce. But the Beth Israel study suggests other immune responses may help ward off the disease, too.

Samples tested against the B.1.351 variant, originally identified in South Africa, showed a five-fold decrease in the amount of disease-fighting antibodies generated by the Johnson & Johnson vaccine, compared to the original strain of the virus. But they showed no reduction in the body’s T cell response and only minimal changes in other types of antibody responses.

Barouch said the data suggest these other immune responses could be a key reason why the one-shot vaccine has proven to be effective against variants. (Barouch’s lab helped design the vaccine.)

Overall, the Johnson & Johnson vaccine has been shown to be 86 percent effective against severe cases of COVID-19 in the United States and 82 percent effective in South Africa, despite the presence of the B.1.351 variant there.

“It is good news,” said Barouch, referring to the new study. “Given that we already know that this vaccine protects well against variants, these data help explain why. Even though the neutralizing antibody responses are reduced, other components of the immune response were not reduced much ... or at all.”

The study found similar trends against the variants first discovered in Brazil, Southern California, and the UK. Barouch emphasized that the Beth Israel study should add to the public’s confidence that the current vaccines have good coverage against variants.

“It is further rationale to vaccinate the world as soon as possible,” he said.

Other vaccine makers have focused some of their recent studies on measuring the impact of variants on disease-fighting antibodies. Moderna released early data in May suggesting that a third dose of its vaccine appeared to raise antibody levels against variants that first emerged in South Africa and Brazil. It also said a tweaked version of its vaccine appeared to work better against the South African variant, citing higher levels of antibodies.

Pfizer released early data in January suggesting that antibodies found in people who received the company’s vaccine appeared to neutralize certain strains of the virus.