A COVID-19 vaccine manufactured by Novavax is 89 percent effective against the disease, but it does not protect as well against a virus variant that has emerged in South Africa. The data also suggest that people who previously had coronavirus infections may not be immune to the South African variant, known as 501Y.V2 or B.1.351, which now circulates in at least 30 countries.
The results came on the same day that health officials reported the first two U.S. cases of COVID-19 caused by the South African variant. He appeared in two people in separate parts of South Carolina with no connection between them. Neither of them had traveled recently, so it’s not clear where they caught the virus.
Gaaversburg, Maryland-based Novavax Inc. presented provisional data from clinical trials in South Africa and the United Kingdom in a January 28 press release. Studies are not yet complete and final efficacy data are expected in February. The company is also conducting a large trial in the United States and Mexico for which no data is yet available.
The Novavax vaccine, given in two separate doses at 21 days, contains a rod-shaped nanoparticle studded with the coronavirus ear protein. It is the first protein-based COVID-19 vaccine for which there are efficacy results. That signature protein leads the body to recognize and manufacture antibodies against the virus, setting up the tools to fight a subsequent infection.
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In the UK, the company conducted a phase III clinical trial to test the effectiveness of the placebo vaccine in more than 15,000 people. Of the 62 cases of COVID-19 that arose among study participants, 56 were in the placebo group and six in the vaccine group. Most cases were mild or moderate. A serious case occurred in the placebo group.
These data indicate that the vaccine protects against serious diseases with an 89.3 percent effectiveness. The vaccine protected almost as well – with an 85.6 per cent efficacy – against the disease of a more transmissible variant of the virus known as B.1.1.7 which has become important in the UK (SN: 22/12/20). In the United States, this strain was also detected in more than half of the states and may become the dominant strain in March (SN: 15/1/21).
The South African trial included about 4,400 adults. When the trial began, a variant of the coronavirus called 501Y.V2 became the predominant variant in the country. This variant is worrying because some evidence suggests that it may escape antibodies that prevent the virus from entering cells (SN: 27/01/20).
In the preliminary analysis of the South African trial, 44 participants obtained COVID-19. Of these, 29, including the only severe case, were in the placebo group and 15 in the vaccine group. The vaccine showed 60 percent effectiveness in preventing severe COVID-19 in people with HIV negatives. When HIV-positive people were added to the equation, the vaccine was 49.4 percent effective in preventing the disease.
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The researchers determined the genetic composition of the virus in 27 of the 44 cases in the study. The 501Y.V2 variant accounted for 25 of those 27 cases, or 92.6 percent.
About a third of participants had antibodies in their blood at the start of the study, indicating they already had previous infections with SARS-CoV-2, the virus that causes COVID-19. But those previous infections did not protect against the new variant.
“The experience of the disease with one wave is not providing immunity to wave two,” Gregory Glenn, Novavax’s president of research and development, said on Jan. 28 during a conference call with investors.
Still, the company is encouraged to show some protection against the variant, Glenn said. Other companies are testing whether their vaccines can also prevent the disease caused by the new variant.
Novavax already has new versions of its vaccine, including one that includes the 501Y.V2 variant, under development and expects to begin clinical trials in the second quarter of 2021, Glenn said.
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