Real-World Effectiveness of J&J Vaccine

Researchers from the USA and India have conducted a study to determine a study demonstrating the real-world effectiveness of a single dose of J&J Ad26.COV2.S vaccine at preventing COVID-19. The study published on a pre-print server compared the SARS-CoV-2 infection rate was compared between 2,195 individuals who received a single dose of the Ad26.COV2.S vaccine and 21,950 unvaccinated, propensity-matched individuals. The team reports that thirteen (0.59%) of 2,195 vaccines tested positive for SARS-CoV-2 by polymerase chain reaction (PCR), compared with 262 (1.19%) of 21,950 unvaccinated individuals.

The incidence rate of SARS-CoV-2-positive tests in the vaccinated and unvaccinated cohorts was 0.18 and 0.36 cases per 1000 person-days, respectively, indicating an overall vaccine efficacy of 50.6%. However, “the full effectiveness of Ad26.COV2.S is expected to be achieved after several weeks,” explains the team. Of 1,779 vaccinated individuals with at least two weeks of follow-up data available, only 3 (0.17%) tested positive for SARS-CoV-2 from day 15 or more following vaccination, compared with 128 (0.72%) of 17,744 unvaccinated individuals.

This corresponds to the efficacy of 76.7% in preventing SARS-CoV-2 infection with symptom onset at least two weeks following vaccination, says the team. The researchers say the study data are consistent with the 66.9% efficacy (66.9%) in preventing moderate-to-severe COVID-19 reported in the phase 3 trial.

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