Early stage clinical trial results show the Covid-19 vaccine candidate made by Novavax is safe and elicits an immune response, according to a study published Wednesday in The New England Journal of Medicine. The results had previously been announced by the company in early August.

What we've learned about Covid-19 seven months after the first US case

Using a randomized, placebo-controlled trial -- the gold-standard method of study -- scientists gave the vaccine or a placebo, an inert substance like saline, to 131 healthy adults in May. Eighty-three people got the vaccine with adjuvant, an agent to boost the body's immune response. Another 25 got the vaccine without the booster and 23 got the placebo. Participants also received a second injection 21 days after the first.

The volunteers came from two locations in Australia and they were all under the age of 60. People who had Covid-19 or who had recovered from Covid-19 were excluded from the trial.