Janssen COVID-19 Vaccine Candidate Found Very Immunogenic

The New England Journal of Medicine published an interim analysis of phase 1–2a trial of the Ad26.COV2.S vaccine on January 13, 2021, and reported an acceptable safety and reactogenicity profile and was immunogenic after a single vaccination with either the low or high dose.

This analysis found a single dose of Ad26.COV2.S elicited a strong humoral response in most vaccine recipients, with the presence of S-binding and neutralizing antibodies in more than 90% of the participants, regardless of either age group or vaccine dose.

Also, during 71 days of follow-up after the first dose, antibody titers further increased and stabilized, suggesting the durability of the Ad26.COV2.S-elicited immune response.

Additionally, the potency of Ad26.COV2.S is supported by the results of a study involving non-human primates, in which a single dose provided complete protection against SARS-CoV-2 virus replication in the lung and near-complete protection in the nose. An efficacious single-dose Covid-19 vaccine has obvious logistic advantages over a two-dose vaccine, especially during a pandemic.

These researchers observed that among participants between the ages of 18 and 55 years, a second vaccine dose at day 57 further increased the antibody titer, a finding that was also in line with our recent observations in nonhuman primates.

Johnson & Johnson's Janssen Vaccines & Prevention B.V. is the sponsor of the experimental COVID-19 vaccine candidate known as 'Janssen COVID-19 Vaccine.'