Observational study showed J&J single shot vaccine had an effectiveness of 74% against symptomatic Covid-19.

Analysis of the Effectiveness of the Ad26.COV2.S Adenoviral Vector Vaccine for Preventing COVID-19 – JAMA Network Open

Commentaries:

Single-Dose Ad26.COV2.S Vaccine—Room for Improvement – JAMA Network Open

Real-world study shows J&J COVID-19 vaccine 74% effective – CIDRAP

Related:

J&J COVID-19 Vaccine: FDA recommends booster shot for all adults aged 18 and older at least two months following initial vaccination with the single-shot vaccine.

[Press release – not published yet] J&J says booster shot at two months provided 75% protection against moderate to severe COVID-19 globally and 94% of such cases in the U.S.

CDC Report: Moderna’s vaccine associated with greater effectiveness (93%) against Covid-19 hospitalization compared to Pfizer (88%) and J&J (71%) vaccines.

[Preprint] Observational study finds single-dose Johnson & Johnson vaccine is 76.7% effective in preventing SARS-CoV-2 infection

RCT: Single-Dose Johnson & Johnson Vaccine has 85% efficacy against severe/critical Covid-19 and maintains efficacy against variant B.1.351