A clinical trial showed that Johnson & Johnson's COVID-19 vaccine is 66 percent effective at preventing moderate to severe disease, the company said Friday.
That level of protection came 28 days after vaccination, according to data from a global phase 3 trial. Onset of protection was observed as early as day 14.
The level rose to 72 percent in the United States. It was 66 percent in Latin American and just 57 percent in South Africa.
“Johnson & Johnson embarked on the global effort to combat the COVID-19 pandemic a year ago, and has brought the full force of our capabilities, as well as tremendous public-private partnerships, to enable the development of a single-shot vaccine. Our goal all along has been to create a simple, effective solution for the largest number of people possible, and to have maximum impact to help end the pandemic,” Alex Gorsky, Johnson & Johnson's CEO, said in a statement.
“We’re proud to have reached this critical milestone and our commitment to address this global health crisis continues with urgency for everyone, everywhere.”
The vaccine is just one shot. Both vaccines authorized for emergency use in the United States require two doses.
The trial showed the vaccine was 85 percent effective in preventing severe disease. Efficacy against severe disease increased over time.
“These topline results with a single-shot COVID-19 vaccine candidate represent a promising moment. The potential to significantly reduce the burden of severe disease, by providing an effective and well-tolerated vaccine with just one immunization, is a critical component of the global public health response,” Paul Stoffels, chief scientific officer for the company, said in a statement.
Adverse events were seen in 9 percent of patients, with more serious adverse events in participants who received placebo as compared to the vaccine candidate.
The trial data wasn't published. Data will be submitted to a peer-reviewed journal in the coming weeks, Johnson & Johnson said. Trial participants will be followed for up to two years, and data may be updated based on ongoing analysis.
Johnson & Johnson plans to file an application in early February to U.S. drug regulators for emergency use authorization. The Food and Drug Administration (FDA) approved vaccines from Moderna and Pfizer last month.
Reception of the reported trial results was generally positive.
"This news is certainly welcome, clearly fulfills FDA threshold, and adds to the vaccine tool chest," Eric Topol, director of the Scripps Research Translational Institute, said in a tweet.
"The J&J vaccine turns in a fantastic result. We now have 3 highly effective vaccines. This vaccine showed sustained (and increasing!) immune protection over time, perhaps from a robust early induction of memory immune cells," added Scott Gottlieb, a former FDA commissioner.
Hours earlier, Novavax announced its vaccine showed an efficacy of 89.3 percent in an interim analysis phase 3 clinical trial in the United Kingdom.
"NVX-CoV2373 is the first vaccine to demonstrate not only high clinical efficacy against COVID-19 but also significant clinical efficacy against both the rapidly emerging UK and South Africa variants," Stanley Erck, president of the Maryland-based company, said in a statement.
The vaccine "has the potential to play an important role in solving this global public health crisis. We look forward to continuing to work with our partners, collaborators, investigators, and regulators around the world to make the vaccine available as quickly as possible," he added.
The trial enrolled more than 15,000 participants but the interm analysis was based on 62 cases, of which 56 cases of COVID-19 were observed in the placebo group.
Novavax said it plans to share further details as additional data become available. The company sought authorization for use in the UK in mid-January.