Novavax skyrockets 21% after saying its COVID-19 vaccine showed promising results in an early trial

• On Tuesday, Novavax announced that its COVID-19 vaccine "elicited robust antibody responses" in an early stage clinical trial.
• Shares of Novavax surged 21% Wednesday.
• The trial included 131 healthy adults between the ages of 18 and 59. It was conducted across two sites in Australia.
• Watch Novavax trade live on Markets Insider.
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Shares of Novavax surged as much as 21% Wednesday after the company announced that an early stage clinical trial of its COVID-19 vaccine produced promising results.

The trial included 131 healthy adults between 18 and 59, and was conducted across two sites in Australia, the company said. Novavax's COVID-19 vaccine, NVX‑CoV2373, "was generally well-tolerated and elicited robust antibody responses," the company said Tuesday.

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The vaccine produced neutralizing antibodies in all patients that received it with mild side effects, the study found. Those who received two shots of the vaccine plus a shot of adjuvant, an ingredient designed to boost immune response, had neutralizing antibody levels that were roughly four times higher than those seen in a group of patients who had recovered from COVID-19.

Novavax is one of many companies including Pfizer and Moderna that are racing to produce a COVID-19 vaccine.

Read more: There are more than 160 coronavirus vaccine candidates being developed. Here's how the top drugmakers see the race for a cure playing out in 2020.

Shares of Novavax have surged more than 4,700% year-to-date.