New J&J Booster Study: 85% Effective Against COVID-19 Hospitalization

Johnson & Johnson today announced new preliminary results from the South African Phase 3b Sisonke study which showed that a homologous (same vaccine) booster shot of the Johnson & Johnson COVID-19 vaccine (Ad26.COV2.S) demonstrated 85 percent effectiveness against COVID-19-related hospitalization. The study, conducted by the South African Medical Research Council (SAMRC), showed that the Johnson & Johnson booster reduced the risk of hospitalization from COVID-19 among healthcare workers in South Africa after Omicron became the dominant variant. During the months studied (mid-November to mid-December) the frequency of Omicron increased from 82 to 98 percent of COVID-19 cases in South Africa as reported by GISAID, an initiative that provides COVID-19 data.     

A second, separate analysis of the immune response to different vaccine regimens, conducted by Beth Israel Deaconess Medical Center (BIDMC), demonstrated that a heterologous booster (different vaccine) of the Johnson & Johnson COVID-19 vaccine in individuals who initially received the BNT162b2 mRNA vaccine generated a 41-fold increase in neutralizing antibody responses and a 5-fold increase in CD8+ T-cells to Omicron by four weeks following the boost. A homologous boost with BNT162b2 generated a 17-fold increase in neutralizing antibodies and a 1.4-fold increase in CD8+ T-cells by four weeks following the boost. Both neutralizing antibodies and CD8+ T-cells were higher four weeks after the boost with the Johnson & Johnson vaccine than with the BNT162b2 vaccine.

The increase in CD8+ T-cells generated by the Johnson & Johnson vaccine may be key to explaining the high levels of effectiveness against severe COVID-19 disease and hospitalization in the Sisonke 2 study, as the Omicron variant has been shown to escape neutralizing antibodies.

The data have been submitted to the pre-print server medRxiv by the studies’ authors, with anticipation of publication in peer-reviewed journals.

Phase 3b Sisonke 2 Booster Shot Study in South African Healthcare Workers

Data from the Sisonke 2 trial (n=227,310), conducted among healthcare workers in South Africa who received the single-shot Johnson & Johnson COVID-19 vaccine as a primary dose, show that the Johnson & Johnson COVID-19 booster increased vaccine effectiveness (VE) against hospitalization to 85 percent. When a booster shot was administered six to nine months after a primary single dose, VE increased over time from 63 percent (95% CI, 31-81%) at 0-13 days, to 84 percent (95% CI, 67-92%) at 14-27 days and 85 percent (95% CI, 54-95%) at 1-2 months post-boost.

Sisonke 2 was conducted in approximately 350 vaccination centers across all nine provinces of South Africa. Utilizing data from Discovery Health, a South African managed care organization, trial investigators determined VE of the Johnson & Johnson COVID-19 booster shot (n=69,092) as compared to other individuals enrolled in the same managed care organization, during the period from November 15, 2021, through December 20, 2021.

Enrollment for the Sisonke 2 arm of the trial commenced just prior to the onset of the Omicron wave in South Africa, allowing researchers to evaluate the effectiveness of the ’s COVID-19 vaccine specifically as Omicron became the dominant variant in the country. Genomic characterization of isolates from COVID-19 cases was not conducted in this trial.

Healthcare workers have an increased risk of being infected with COVID-19, and in countries such as South Africa, which have a significant population living with comorbidities, the impacts of SARS-CoV-2 infections in healthcare workers are especially profound. The majority of South African healthcare workers who have died of COVID-19 had at least one comorbidity, and many had multiple comorbidities.

Antibody and T-Cell Responses After Heterologous Boosting Regimen Greater than After Homologous Regimen Against Omicron Variant

An analysis of 65 individuals who received primary vaccination with two doses of an mRNA COVID-19 vaccine (BNT162b2), followed by a homologous booster shot of BNT162b2 (n=24) or a heterologous booster with the Johnson & Johnson COVID-19 vaccine (n=41) after at least six months, found both regimens increased humoral and cellular responses against Omicron.

Antibody responses against Omicron were boosted by both the Johnson & Johnson COVID-19 vaccine and the BNT162b2 vaccine, with the Johnson & Johnson COVID-19 vaccine increasing neutralizing antibody titers by 41-fold at four weeks post-boost. The BNT162b2 vaccine was found to increase antibody titers to a higher level at week two post-boost, before declining to represent a 17-fold increase at week four post-boost. The progressive increase in antibodies the weeks following a vaccination of a Johnson & Johnson booster is similar to that seen following the first vaccine. The rapid immune response followed by waning of the antibody response after the BNT162b2 booster is also similar to that seen following the two-dose priming regimen.

The Johnson & Johnson COVID-19 vaccine boosted median Omicron-reactive CD8+ T-cells by 5.5-fold, and Omicron-reactive CD4+ T-cells by 3.1-fold, while the homologous (BNT162b2) regimen boosted both Omicron-reactive CD4+ and CD8+ T-cells by 1.4-fold.

T-cells can target and destroy cells infected by the virus that causes COVID-19 and are believed to contribute to protection against severe disease. Specifically, CD8+ T-cells can directly destroy infected cells and are aided by CD4+ T-cells.

These data suggest that heterologous boosting has the potential to induce strong cell-mediated immunity, which is important for immune memory and protection against severe lower respiratory tract disease. The durability of heterologous and homologous boost regimens for the SARS-CoV-2 Omicron variant remain to be determined.

Additional Information

The Johnson & Johnson COVID-19 vaccine has been authorized as booster by multiple regulators and healthcare bodies around the world. Johnson & Johnson continues to submit relevant data to other regulators, the World Health Organization (WHO) and National Immunization Technical Advisory Groups (NITAGs) worldwide to inform decision-making on local vaccine administration strategies, as needed.

On December 16, 2021, the U.S. Centers for Disease Control and Prevention (CDC) endorsed updated recommendations made by the Advisory Committee on Immunization Practices (ACIP) for the prevention of COVID-19, expressing a clinical preference for individuals to receive an mRNA COVID-19 vaccine over the Johnson & Johnsons COVID-19 vaccine. In the U.S., individuals who are unable or unwilling to receive an mRNA vaccine will continue to have access to the Johnson & Johnson COVID-19 vaccine.

The Johnson & Johnson COVID-19 vaccine is an important choice for people who can’t or won’t return for multiple vaccinations or who would remain unvaccinated without an alternative to the mRNA vaccines. The Johnson & Johnson COVID-19 vaccine aligns with the World Health Organization’s (WHO) recommendations for medical interventions in a pandemic setting, which emphasize ease of distribution, administration, and compliance.

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