J&J COVID-19 Booster Strongly Protects Against Hospitalization

Two doses of the Johnson & Johnson (J&J) COVID-19 vaccine (Ad26.COV2.S) cut the risk of a COVID-related hospitalization by 85 percent, the company has reported — and the benefit may be coming from ramped-up T-cells rather than vaccine-induced antibodies.

The hospitalization study was conducted in more than 69,000 South African healthcare workers who had been vaccinated and boosted with the adenovirus-vector vaccine six to nine months after the primary dose. From mid-November to mid-December, double vaccination significantly increased protection against hospitalization over single vaccination, said Linda-Gail Bekker of the University of Cape Town, who led the study.

Vaccine efficacy against hospitalization increased over time since booster dose, Bekker and her colleagues said. Single-dose protection was 63 percent; by 13 days after boosting, it had risen to 84 percent, where it hovered for up to two months after the booster.

The study — which hasn’t yet been peer-reviewed — didn’t break down COVID-19 cases by strain. But it looked at hospitalization rates during South Africa’s Omicron surge, so it’s not unreasonable to suggest that the two-jab protocol protects against Omicron-related hospitalization.