Novavax vaccine 89% effective, according to clinical trials

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Clinical trials of the two-dose Covid-19 vaccine of Novavax have shown an efficacy of 89.3%, the US biotechnology company said Thursday in a press release posting the results of phase 3 trials.

“NVX-CoV2373 has the potential to play an important role in solving this global public health crisis,” said company CEO Stanley Erck.

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85.6% efficacy against the British variant

British Prime Minister Boris Johnson welcomed this “good news” on Twitter, adding: “Our medical regulatory authorities will now assess the vaccine (…). If it’s cleared, we have an order for 60 million doses ”.

The vaccine was one of six candidates backed by the US government that funded the project to the tune of $ 1.75 billion. Clinical trials are also underway in the United States and Mexico, with 16,000 and 30,000 participants respectively.

The clinical trials, conducted in the UK, involved 15,000 people between the ages of 18 and 84, 27% of whom were over 65.

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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.

Development of a new vaccine targeting the South African variant

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. According to the company, this variant was responsible for 90% of the cases that were the subject of sequencing. 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.

A success despite this lower efficiency

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.

A worrying detail, Novavax claimed that a third of the participants in the South African trials had already been infected with the original strain of the virus, while the infections that took place during the study were largely from the variant that appeared in South Africa. . “These data suggest that a previous Covid-19 infection does not necessarily completely protect against subsequent infection with the South African variant,” the company said.

To continue reading: Covid deaths and vaccines: no link established but strict monitoring

But for Amesh Adalja, a doctor and professor at the Center for Health Security at Johns Hopkins University in the United States, it is important to keep this drop in efficiency in context. The Novavax vaccine is still a success, he told Agence France-Presse (AFP).

“Sixty percent (effective) against the variant is still pretty good,” said Dr Adalja. “Clearly the Novavax vaccine prevented severe forms of the disease, which is most important in the end.”

Pressure on Johnson & Johnson

The results are the first to assess the effectiveness of vaccines against the British and South African variants, in the real world.

Pfizer and Moderna have previously claimed that their respective vaccines remain effective against variants, but their studies were conducted in a laboratory setting.

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Novavax’s announcement put some pressure on another vaccine maker, Johnson & Johnson, whose Phase 3 trial results are due next week.