On Thursday, Novavax announced that its vaccine was 89% effective, according to its UK trials which had 15 000 participants. However, its SA trials showed a much lower effectiveness of 49.4%, believed to be caused by the SA COVID variant B.1.351 (aka 501.V2).
The company conveyed the information in a press release, with a detailed journal publication still to come. The SA trial had 4400 participants, and the observed protection varied depending on HIV status. In people who were HIV negative, the vaccine conferred 60% protection. If the vaccination trial included a representative proportion of HIV positive adult South Africans, it may mean that its effectiveness for this vulnerable segment is very low.
“The higher efficacy of the vaccine in the UK than in South Africa is because the variants circulating in SA are less sensitive to vaccine induced immune responses,” said Professor Shabir Madhi, Executive Director of the Vaccines and Infectious Diseases Analytics Research Unit (VIDA) at Wits, and principal investigator in the Novavax COVID vaccine trial in SA.
“Nevertheless, the 60% reduced risk against Covid-19 illness in vaccinated individuals in South Africans underscores the value of this vaccine to prevent illness from the highly worrisome variant currently circulating in South Africa, and which is spreading globally. This is the only Covid-19 vaccine for which we now have objective evidence that it protects against the variant dominating in South Africa.”
Novavax is pressing ahead with a trial involving 30 000 participants in the United States and Mexico, and has shared data with the UK’s pharmaceutical regulator. It is not clear whether the data from the US and Mexico trial will be required before the vaccine receives approval there. Meanwhile on Friday, the Johnson & Johnson vaccine developed by its subsidiary Janssen has been shown to be 66% effective. It is a single dose vaccine with minimal refrigeration requirements, making it very important for the logistical challenge of vaccinations in developing countries. Since Aspen would be producing some of the doses locally, the SA government had been in talks with Johnson & Johnson to secure some of those vaccines for SA use. However, there are signs that it too is less effective against the B.1.351 variant.
Source: Business Insider
