Johnson & Johnson on Friday reported data from a laboratory study demonstrating that its single-dose COVID-19 vaccine Ad26.COV2.S induced "strong, persistent activity" against the Delta variant (B.1.617.2) and other highly prevalent SARS-CoV-2 strains. The company said data also suggest its vaccine generates immune responses lasting for at least eight months. The new findings, which have been submitted as preprints to bioRxiv, "reinforce the ability of [our] vaccine to help protect the health of people globally," according to chief scientific officer Paul Stoffels.
Regarding the new Delta analysis, researchers looked at blood samples from eight people enrolled in the pivotal Phase III ENSEMBLE study  used to support Johnson & Johnson's regulatory filings for Ad26.COV2.S. The vaccine was given a green light  for emergency use by the FDA in February, with regulators in the EU , UK and other markets following suit. However, demand for the vaccine has fizzled , notably in the US where it had the largest rollout, after it was linked to a rare blood-clotting  disorder, while possible contamination at a Baltimore manufacturing plant have forced the company to throw out  millions of doses.
Johnson & Johnson said that in the new analysis, Ad26.COV2.S produced neutralising antibody activity against Delta "at an even higher level than what was recently observed  for the Beta (B.1.351) variant in South Africa where high efficacy against severe/critical disease was demonstrated." The ENSEMBLE trial data had shown the vaccine was 85% effective against severe/critical COVID-19 illness, and "consistently effective" across all global study sites, the company said, including in South Africa and Brazil, where there was a high prevalence of rapidly emerging Beta and Zeta (P.2) variants.
Separate analyses conducted in England and Scotland recently found that Pfizer and BioNTech's vaccine Comirnaty (BNT162b2) and AstraZeneca's Vaxzevria (AZD1222) also offered substantial protection from the Delta variant against severe cases of COVID-19 and hospitalisation.
Meanwhile, Johnson & Johnson stated that a sub-analysis of 20 people taking part in a Phase I/IIa of its vaccine, showed that humoral and cellular immune responses lasted through at least eight months, which was the latest time-point recorded in the study to date. It said data showed that T-cell responses, including CD8+ T-cells, persisted over that timeframe. Moreover, a single dose elicited neutralising antibodies that "increased over time" against a range of SARS-CoV-2 variants of concern, the company said, with the average neutralising titre at eight months exceeding the level produced at the one-month mark. According to Johnson & Johnson, this was true for Delta as well as the Beta, Gamma (P.1), Alpha (B.1.1.7), Epsilon (B.1.429) and Kappa (B.1.617.1) strains.