Washington – US biotechnology company Novavax said on Thursday that its two-shot COVID-19 vaccine looked global 89.3% efficiency in a major phase 3 clinical trial in the UK and remained very effective against a variant first identified there. But the positive news was offset somewhat by other results that showed less protection against a highly transmissible variant of coronavirus first identified in South Africa.
Like the British strain, the variant first found in South Africa is spreading rapidly around the world, and the first cases have been confirmed in the US. There have been concerns in recent weeks that vaccines developed around the world may be less effective against the South African variant in particular, and while the results of the Novavax study seem to confirm some level of resistance, both the company and an external expert in the field of health were optimistic about the level of protection offered against both new strains.
“NVX-CoV2373 has the potential to play an important role in resolving this global public health crisis,” said Stanley Erck, president and CEO, using the name Novavax for the vaccine. “We look forward to continuing to work with our partners, collaborators, investigators and regulators around the world to make the vaccine available as soon as possible.”
British Prime Minister Boris Johnson wrote on Twitter that the results were “good news”, adding that UK regulators would now evaluate the vaccine for potential approval.
The vaccine was one of six candidates backed by a U.S. government project previously known as Operation Warp Speed, which offered the Maryland-based company $ 1.75 billion. It is also being tested in a trial in the US and Mexico, which has so far recruited about 16,000 out of 30,000 participants.
Unlike the Pfizer, Moderna and AstraZeneca vaccines, which provide the genetic instructions that cause human cells to create a key protein in the virus, Novavax shot injects the proteins directly into the body to evoke an immune response.
“Pretty good” vs. strain from South Africa
The British trial involved 15,000 people aged between 18 and 84, including 27% over the age of 65. The first interim analysis was based on 62 cases of confirmed COVID-19 among participants, of which 56 cases were observed in the placebo group versus six cases among people who received the vaccine.
Preliminary analysis of the company indicated that the variant first identified in the United Kingdom, called B.1.1.7, was detected in more than 50% of confirmed cases. Novavax said the results showed that their 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 mid-stage study in South Africa. The study enrolled just over 4,400 patients from September to mid-January, when variant B.1.351, which contains critical mutations along the virus’s peak protein, spread rapidly across the country.
Overall efficacy was 49.4% in this study, but this figure increased to 60% among the 94% of study participants who were HIV-negative.
Worryingly, Novavax said that about a third of the study participants in South Africa were previously infected with the original form of the virus, while subsequent infections during the study were largely of that variant.
The results come just days after South African researchers told CBS News that the new strain had appeared in the country very resistant to antibodies in blood samples from people who were infected with the original strain of the virus, first detected in Wuhan, China in late 2019. This research has left scientists concerned that the previous infection could provide reduced immunity to the new variants of South Africa and the effectiveness of vaccines.
Amesh Adalja, chief physician and researcher at the Johns Hopkins Center for Health Security, told AFP, however, that it was important to keep the effectiveness low in the future, and the vaccine was still a success.
“Sixty percent against the variant is still pretty good,” he said. “Clearly, the Novavax vaccine has prevented severe disease, which is really what matters most.”
Professor Shabir Madhi, who is leading the trials in South Africa, said on Thursday night that the results from Novavax were something he had “never dreamed of” when he saw how weak the natural immunity from the first wave of COVID infections with the original strain , was against the South African variant.
Novavax CEO Erck called the preliminary results of the study’s effectiveness in South Africa “beyond people’s expectations.”
Studies in the UK and South Africa were the first to evaluate the performance of a COVID-19 vaccine against UK and South African variants in real-world studies.
Modern previously said it is the vaccine “should” remain effective against both new highly infectious variants, but the study he cited was based on laboratory research, not actual testing against human infection.
Pfizer also has reported laboratory results which suggests that its vaccine will prove effective against the UK variant, but has not yet revealed data for testing against the strain prevalent in South Africa.