“NVX-CoV2373 has the potential to play an important role in solving this global public health crisis,” said company CEO Stanley Erck.
But the positive news was offset by the joint announcement that the vaccine is much less effective against the variant first identified in South Africa, which scientists consider to be more contagious.
The company will immediately embark on the development of a new vaccine targeting this variant, the statement said.
The clinical trials, conducted in the UK, involved 15,000 people between the ages of 18 and 84, of whom 27% were over 65.
The first interim analysis was based on 62 cases of Covid-19, of which 56 were observed in the placebo group, against six cases among those who received the NVX-CoV2373 vaccine.
The company’s preliminary analysis indicates that the variant first identified in England, B.1.1.7, has been detected in more than 50% of confirmed cases.
The vaccine efficacy per strain of the coronavirus was estimated to be 95.6% against the original strain, and 85.6% against the variant that appeared in the United Kingdom.
But the effectiveness appears to be much lower in a smaller study conducted in South Africa.
The latter involved just over 4,400 patients, from September to mid-January, a period during which the B.1.351 variant spread widely across South Africa.
The overall vaccine efficacy was 49.4% in these trials, but the number rose to 60% among the 94% HIV-negative participants.
Novavax said it began research on new vaccines against emerging variants in early January, and expects to screen optimal vaccine candidates in the coming days, before starting clinical trials in the second quarter.
Unlike the vaccines from Pfizer and Moderna, which use messenger RNA technology, the injection of the Novavax vaccine includes fragments of the coronavirus which make it possible to elicit an immune response in the human body.