Washington – The American biotechnology company Novavax said on Thursday that its two-dose COVID-19 vaccine showed a 89.3% effectiveness in a large Phase 3 clinical trial in Britain and remained highly effective against a variant first identified there. But the positive news was offset in some way by other results that showed it offered less protection against a highly transmissible variant than coronavirus first identified in South Africa.
Like the UK strain, the variant first found in South Africa is now spreading rapidly across the world, and the first cases have been confirmed in the United States. There has been concern in recent weeks that vaccines developed worldwide could be less effective against South Africa’s variant in particular, and although the results of the Novavax study appear to confirm some level of resistance, both the company and a specialist in external health professionals were optimistic about the level of protection provided against the two new strains.
“NVX-CoV2373 has the potential to play an important role in solving this global public health crisis,” said company president and CEO Stanley Erck, using the name of Novavax for the vaccine. “We look forward to continuing to work with our partners, employees, researchers and regulators around the world to make the vaccine available as soon as possible.”
British Prime Minister Boris Johnson tweeted that the results were “good news”, adding that UK drug regulators would now evaluate the vaccine for possible approval.
The vaccine was one of six candidates supported by a U.S. government project previously known as Operation Warp Speed, which provided the Maryland-based company with $ 1.75 billion. It is also being tested in a trial in the US and Mexico, which has recruited about 16,000 of the 30,000 participants so far.
Unlike the Pfizer, Moderna and AstraZeneca vaccines, which deliver the genetic instructions that make human cells create a key virus protein, the Novavax vaccine injects proteins directly into the body to evoke an immune response.
“Very good” vs. South African variety
The British trial involved 15,000 people aged 18 to 84, including 27% over 65. The first provisional analysis was based on 62 confirmed cases of COVID-19 among the participants, of which 56 cases were seen in the placebo group versus six cases among people who received the vaccine.
The company’s preliminary analysis indicated that the variant first identified in the UK, called B.1.1.7, was detected in more than 50% of confirmed cases. Novavax said the results showed that the vaccine was 95.6% effective against the original COVID-19 strain and 85.6% against the UK variant.
But the level of protection was lower in a smaller intermediate-stage test in South Africa. This study involved just over 4,400 patients from September to mid-January, a period in which variant B.1.351, which contains critical mutations over of the virus’s spike protein, was spreading rapidly across the country.
The overall effectiveness was 49.4% in this study, but that number increased to 60% among the 94% of study participants who were HIV negative.
Worryingly, Novavax said that about a third of study participants in South Africa had previously been infected with the original form of the virus, while subsequent infections during the study were largely of the variant.
The results came just days after South African researchers told CBS News that the new strain in the country appeared highly resistant to antibodies in blood samples from people infected with the original strain of the virus, first detected in Wuhan, China, in late 2019. This research worried scientists that the previous infection might provide little immunity to the new variant in Africa South and possible impact on vaccine effectiveness.
Amesh Adalja, a doctor and senior researcher at the Johns Hopkins Center for Health Safety, told AFP, however, that it was important to keep the diminished effectiveness in perspective, and the vaccine was still a success.
“Sixty percent against the variant is still very good,” he said. “Clearly, the Novavax vaccine prevented serious illness, which in the end is what matters most.”
Professor Shabir Madhi, who is conducting the South African tests, said on Thursday night that Novavax results were something “he did not dream of” when he saw how the natural immunity of the first wave of COVID infections, with the original strain, the variant did poorly in South Africa.
Novavax CEO Erck called the preliminary results of the study’s effectiveness in South Africa “above people’s expectations.”
The studies in Britain and South Africa were the first to assess the performance of a COVID-19 vaccine against the United Kingdom and South Africa variants in tests in the real world.
Moderna has already said it is vaccine “must” remain effective against both new highly infectious variants, but the study he cited was based on laboratory research, not on real-world tests against human infection.
Pfizer too reported laboratory results who suggest that his vaccine will be effective against the UK variant, but has yet to reveal any data for testing against the strain prevalent in South Africa.