Novavax enters final stage of vaccine trials

Early studies show especially robust antibody results.

Vaccine maker Novavax said Thursday that it would begin the final stages of testing its coronavirus vaccine in the United Kingdom and that another large trial was scheduled to begin next month in the United States.

It is the fifth late-stage trial from a company supported by Operation Warp Speed, the federal effort to speed a coronavirus vaccine to market, and one of 11 worldwide to reach this pivotal stage. Novavax, a Maryland company that has never brought a vaccine to market, reached a $1.6 billion deal with the federal government in July to develop and manufacture its experimental vaccine, which has shown robust results in early clinical trials.

The new study, known as a phase 3 trial, is expected to enroll up to 10,000 people in the United Kingdom. Half of the volunteers will receive two doses of the experimental vaccine 21 days apart, and the others will receive a placebo.

Although Novavax is months behind the front-runners in the vaccine race, independent experts are excited about its vaccine because its early studies delivered particularly promising results. Monkeys that were vaccinated got strong protection against the coronavirus.

And in early safety trials, published early this month in The New England Journal of Medicine, volunteers produced strikingly high levels of antibodies against the virus.

It is not possible to make a precise comparison among early clinical studies of different vaccines, but John Moore, a virologist at Weill Cornell Medicine, said the antibodies from Novavax were markedly higher than any other vaccine with published results. “You just can’t explain that away,” he said.

The phase 3 trials will determine if Novavax can live up to that promise. Although the British trial is smaller than those of other leading vaccines, the vaccine’s potency means that it might deliver clear results well before the trial is over, said Natalie Dean, a biostatistician at the University of Florida. Researchers analyze clinical trial data at predetermined points during the study.

“That’s one of the reasons why we have those types of analyses: to catch a home run if something is working exceptionally well,” she said.

Paul Heath, professor of pediatric infectious diseases at St. George’s, University of London and the lead scientist of the trial, said that the team would make a special effort to recruit people who are at higher risk of getting sick.

“We will be reaching out to health and social care workers and others who are on the front line and therefore are more likely to be exposed,” Heath said.

Novavax said the trial would seek to enroll at least a quarter of its participants over age 65 and would prioritize groups most affected by COVID-19, including racial and ethnic minorities.

If the surge of COVID-19 continues in the United Kingdom, Heath said, the trial could determine if the vaccine is effective in several months.