Johnson & Johnson (J&J) has announced that new preliminary results from the South African phase 3b Sisonke study show that a booster shot of the J&J COVID-19 vaccine is 85% effective in preventing hospitalisation for COVID-19.
The study was conducted by the South African Medical Research Council (SAMRC) among healthcare workers in approximately 350 vaccination centres across all nine provinces of South Africa after Omicron became the dominant variant.
The study was done from mid-November to mid-December when, according to GISAID, an initiative that provides COVID-19 data, the dominance of the Omicron variant increased from 82% to 98% of COVID-19 cases in South Africa.
In Israel, the Beth Israel Deaconess Medical Center (BIDMC) conducted a second, separate analysis of the immune response to different vaccine regimens, which showed that J&J’s COVID-19 vaccine booster generated a 41-fold increase in neutralising antibodies and a 5-fold increase in T-cells against Omicron.
The increase in T-cells generated by the J&J vaccine may be key to explaining the high levels of effectiveness against severe COVID-19 disease and hospitalisation in the Sisonke 2 study, as the Omicron variant has been shown to escape neutralising antibodies.
Mathai Mammen, global head, Janssen Research & Development, Johnson & Johnson said: “Data from the Sisonke 2 study confirms that the Johnson & Johnson COVID-19 booster shot provides 85% effectiveness against hospitalisation in areas where Omicron is dominant. This adds to our growing body of evidence which shows that the effectiveness of the J&J COVID-19 vaccine remains strong and stable over time, including against circulating variants such as Omicron and Delta.
“We believe that the protection could be due to the robust T-cell responses induced by the Johnson & Johnson COVID-19 vaccine. Furthermore, the data suggests that Omicron is not affecting the T-cell responses generated by our vaccine.”
Glenda Gray, president and CEO of SAMRC said: “Even before you factor in the increased infectiousness of Omicron, we have to remember that healthcare workers on the frontlines are at a greatly increased risk of being affected by COVID-19 in the first place.
“We are therefore encouraged to see that boosting with the Johnson & Johnson COVID-19 vaccine regimen provides strong protection in a challenging real-world setting where there is an elevated risk of exposure – not just to COVID-19, but to the highly transmissible Omicron variant.”
The data has been submitted to the pre-print server medRxiv by the studies’ authors.