In a multicountry clinical trial, Johnson & Johnson says that a booster shot of its COVID-19 vaccine increased protection against contracting the disease, according to a news release.
The data came from the company’s Phase 3 ENSEMBLE 2 study, which is a randomized, double-blind, placebo-controlled clinical trial designed to evaluate the safety and efficacy of a two-dose vaccine regimen, given at a 56-day interval, versus placebo in adults 18 years old and older with and without comorbidities associated with an increased risk for severe COVID-19.
Johnson & Johnson’s data has not yet been peer reviewed or published in a medical journal.
The company’s study was designed to assess efficacy of the vaccine after both the first and second dose to evaluate protection against the virus and potential incremental benefits for duration of protection with a second dose. In the ENSEMBLE 2 Phase 3 study, solicited and unsolicited adverse events following this second dose are similar to those seen in single-dose studies.
Compared to the single-dose results, ENSEMBLE 2 demonstrated increased efficacy of a two-dose schedule in which the second shot is given 56 days after the first. The study demonstrated 100% protection against severe or critical COVID-19 at least 14 days following the second vaccination.
In addition, the company said, the booster dose provided 75% protection against symptomatic COVID-19, which includes both moderate and severe cases, in all of the countries included in the study. In the U.S. specifically, efficacy against moderate to severe/critical COVID-19 was 94%.
Median follow-up time in the ENSEMBLE 2 study was 36 days since second vaccination, with 29% percent of participants having at least two months of follow-up after receipt of their second dose.
The company said it has provided available data to the U.S. Food and Drug Administration (FDA) and plans to submit the data to other regulators, the World Health Organization (WHO) and National Immunization Technical Advisory Groups (NITAGs) worldwide to inform decision-making on local vaccine administration strategies.
