Researchers say booster dose of Johnson & Johnson’s (NYSE:JNJ) single-dose COVID-19 vaccine was 84% effective at preventing hospitalization in South African health-care workers who became infected as the omicron variant spread.
The real-world study, which has not been peer-reviewed, was based on a second dose of the J&J vaccine administered to 69,092 workers between Nov. 15 and Dec. 20.
An initial course of inoculation has been shown to offer only greatly reduced protection against infection by omicron, which is spreading quickly through many countries after first being identified in southern Africa and Hong Kong in late November.
However, several studies have suggested that a booster dose provides significant protection against severe illness from the variant.
The South African study showed the J&J vaccine’s effectiveness at preventing hospitalization rose from 63% shortly after a booster was administered to 84% 14 days later. Effectiveness reached 85% at one to two months post-boost.
One of the researchers said the jury was "still out" on the issue of further boosters for the J&J vaccine, which is administered as a single shot for the first full dose, and which is easier to transport to remote African rural areas than the rival, two-dose Pfizer mRNA vaccine due to better heat tolerance.
Researchers said their analysis had several limitations, including short follow-up times. Those averaged eight days for healthcare workers who had received their boost within the previous 13 days, or 32 days for those boosted one or two months earlier.
JNJ shares gained 68 cents to $172.23.
