Johnson & Johnson’s vaccine produced virtually no antibody protection against the omicron coronavirus variant in a laboratory experiment, underlining the new strain’s ability to get around one pillar of the body’s defenses.

The vaccine appears to provide some defense against omicron, perhaps via other means such as stimulation of immune cells, according to Penny Moore, a South African virologist. The findings are consistent with other studies that show a partial loss of potency against COVID-19 for a number of vaccines, with J&J’s antibody protection looking particularly weak in the lab test.

Moore, a professor at Johannesburg’s University of The Witwatersrand, said that laboratory experiments were conducted on blood plasma samples from people who had had two doses of the Pfizer Inc. and BioNTech SE vaccine and those or the J&J single-shot inoculation.

A measure of antibody levels, called geometric mean titers, fell from 1,419 against the original coronavirus strain to 80 against omicron among people who received Pfizer shots. The same measure fell from 303 against the original strain to undetectable levels against omicron in those who had received J&J’s shot, Moore said in an online presentation on Tuesday.

“Omicron does indeed exhibit substantial immune escape from antibodies,” she said. “The situation, I think, is even more alarming for the J&J vaccine — there was no detectable neutralization in our assay.”

J&J didn’t declined to comment on the findings, referring instead to an earlier statement that said the company is testing serum from participants in its booster studies to look for neutralizing activity against omicron while pursuing an variant-specific vaccine that it will progress as needed. The company is “confident in the robust humoral and cell-mediated immune responses elicited” by its vaccine, Mathai Mammen, head of research & development for J&J’s Janssen pharma unit, said in the statement.

Severe Disease

The as-yet unpublished research Moore presented to an African health conference ties in with early experiments by South Africa’s Africa Health Research Institute and Pfizer’s own research. Omicron’s discovery was announced by South African scientists on Nov. 25.

Still, Moore stressed, the body has other protection against the virus.

“Reduced antibody titers will likely result in decreased ability of vaccines to prevent infection but protection against severe disease likely to be preserved,” she said on one of her presentation slides.

J&J’s vaccine appears to be preventing severe disease in a study involving hundreds of thousands of South African health workers and no one on the study has died after being infected by the omicron variant, Glenda Gray, the co-lead of the study said in an earlier presentation on Tuesday.

Discovery Health Ltd., the country’s largest medical insurance provider, said earlier today that a two-shot course of Pfizer’s vaccine appeared to offer 70% protection against being hospitalized after infection with the omicron variant. The shots made by Pfizer and J&J are the two currently being used in South Africa.