Interim Results of Johnson & Johnson Single-Dose COVID-19 Vaccine Shows 90% Efficacy

The single dose investigational vaccine being developed by the Janssen Pharmaceutical Companies of Johnson & Johnson is a recombinant, replication-incompetent adenovirus serotype 26 vector encoding a stabilized SARS-CoV-2 spike protein.

Johnson & Johnson’s (J&J) JNJ-78436735 COVID-19 vaccine was shown to be 90% efficacious in interim results, according to findings published in the New England Journal of Medicine. The single dose investigational vaccine, which is being developed by the Janssen Pharmaceutical Companies of Johnson & Johnson, is more commonly referred to as the Ad26.COV2.S vaccine, and is a recombinant, replication-incompetent adenovirus serotype 26 (Ad26) vector encoding a full-length and stabilized SARS-CoV-2 spike (S) protein.

After a single dose vaccination, data showed neutralizing antibodies against COVID-19 were detected in over 90 percent of study participants at Day 29 and 100% of participants aged 18-55 years at Day 57. These neutralizing antibodies remained stable through Day 71, currently the latest timepoint available in this ongoing study, in all participants aged 18-55 years. The company plans to release data in participants 65 years and older in late January.

The phase 1/2a analysis showed that the company’s COVID-19 vaccine candidate was generally well-tolerated across all study participants. While the vaccine is being studied as a single dose administration shot, the trial did evaluate 2 dose administration. The data showed that a second dose of JNJ-78436735, administered 56 days apart, was less reactogenic while it triggered more than a two-fold increase in antibodies against COVID-19.

“Although all ongoing phase 3 studies of other Covid-19 vaccines have assessed two-dose schedules, a single dose of Ad26.COV2.S elicited a strong humoral response in a majority of 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,” the investigators wrote.

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