Shares of Novavax (NASDAQ: NVAX) were up 2.3% as of 12:03 p.m. EDT on Wednesday after moving 4.2% higher earlier in the day. The company didn’t report any news, so it’s possible that today’s gain could be in response to Altimmune (NASDAQ: ALT) throwing in the towel on its experimental nasal COVID-19 vaccine after disappointing clinical results. But Novavax’s move could also simply be a continuation of momentum that began last week.