A woman holds a small bottle with a sticker “Coronavirus COVID-19 Vaccine” and a medical syringe in front of the Novavax logo displayed in this image dated October 30, 2020.

Given Ruvic | Reuters

Biotech company Novavax said Monday its Covid-19 vaccine had been shown to be safe and 90.4% overall effective in a Phase III clinical trial involving nearly 30,000 participants in the United States and Mexico.

In addition, the two-dose vaccine was found to be 100% effective in preventing moderate and severe illness and 93% effective in some variants, Novavax said. The company plans to file for regulatory approval with the Food and Drug Administration in the third quarter of this year.

The late-stage study “confirms that NVX-CoV2373 has an encouraging tolerability and safety profile,” said Dr. Gregory Glenn, President of Research and Development at Novavax, in a press release. “These data show consistent, high efficacy and reaffirm the vaccine’s ability to prevent COVID-19 amid the virus’ s ongoing genetic evolution.”

The analysis evaluated 77 confirmed Covid infections among the 29,960 participants in the study. Novavax said 63 cases of Covid were seen in the placebo group, up from 14 cases seen in the group that received their two-dose vaccine. That resulted in an estimated vaccine effectiveness of 90.4%, it said.

The vaccine also appeared to be well tolerated, the company said. The most common side effects were fatigue, headache, muscle aches and pain at the injection site, which usually didn’t last more than two or three days, the company said.

All Covid hospital admissions in the study were in the placebo group, the company said.

Novavax said the vaccine appears to be effective against a few variants, including the alpha variant, which was first identified in the UK. About 65% of the cases where sequence data were available were of worrying variants, the company said.

If Novavax’s vaccine is FDA approved, it would follow three Covid-19 vaccines already approved in the U.S. by Pfizer-BioNTech, Moderna, and Johnson & Johnson for emergency use.

The new data comes as federal officials say the U.S. has more than enough doses of Covid vaccine to vaccinate the entire American population. According to the Centers for Disease Control and Prevention, more than 173 million Americans had received at least one dose of a Covid-19 vaccine as of Sunday.

It is possible that the US will end up donating doses of the Novavax vaccine.

The Biden government has already committed to donating at least 20 million doses of Covid vaccines from Pfizer-BioNTech, Moderna and J&J, as well as 60 million doses of AstraZeneca vaccines that are not yet approved for use in the United States

Earlier this month, the White House announced it was lifting restrictions under the Defense Production Act, which gives the US priority to vaccines developed by AstraZeneca, Sanofi and Novavax.

Novavax said Monday it is still on track to hit production capacity of 100 million cans per month by the end of the third quarter and 150 million cans per month by the fourth quarter of 2021.