AstraZeneca Covid-19 weaker vaccine against the South African strain

The study, which enrolled approximately 2,000 volunteers with a median age of 31 years, was too small and its participants were too young to draw broad conclusions about the overall effectiveness of the vaccine in protecting against coronavirus disease, more chosen when it comes to hospitalizations or death. . However, its findings contribute to the concern that a mutant virus makes existing Covid-19 vaccines less effective and that vaccines will need to be updated to protect against new strains of the virus.

Johnson & Johnson and Novavax Inc.,

whose vaccines have not yet been authorized in any country, have also found that their vaccines have been less effective in recent human clinical trials in South Africa. But their vaccines have been shown to be still 50% or more effective in preventing mild to moderate cases of Covid-19 and even stronger in protecting beneficiaries from severe disease and hospitalization of the new strain.

Sunday’s press release on the AstraZeneca study in South Africa did not provide a vaccine efficacy rate. The Johnson & Johnson trial in South Africa involved about 6,500 people, while the one in Novavax had 4,400.

The University of Witwatersrand in Johannesburg, which conducted the AstraZeneca study, said it cannot assess whether the vaccine provides protection against more severe cases of Covid-19 because relatively young study participants have a lower risk of developing severe Covid. -19 symptoms.

However, the lead researcher on South African studies and Oxford University scientists who developed the AstraZeneca vaccine said that based on the results of other vaccine studies, they were optimistic that their shot would provide protection against Covideca. 19 sever.

“This study confirms that pandemic coronavirus will find ways to continue to spread to vaccinated populations, as expected,” said Andrew Pollard, director of the Oxford Vaccine Group at Oxford University, in a press release on the results of the study. . But, taken with promising results from other studies in South Africa, using a similar viral vector, vaccines can continue to ease the burden on health systems by preventing severe disease.

An AstraZeneca spokesman said the company believes “our vaccine could protect against severe disease.”

The South African strain, known as B.1.351, is already responsible for most infections in South Africa and has been blamed for a sharp rise in Covid-19 cases in countries such as Mozambique and Zambia in recent weeks.

Researchers in the US, Canada, Israel and a number of European and African countries have also detected it in positive coronavirus testing from people with no recent travel history, suggesting that it is spreading in the community. In total, it has been identified in 32 countries, and virologists say it is likely to be present in others that do not systematically sequence positive test samples.

Scientists in South Africa and the United Kingdom estimate that strain B.1.351 is about 50% more contagious than previous versions of the virus, based on the much faster growth of Covid-19 infections during the second wave of South Africa compared to the first and biological studies of changes in the structure of the virus.

South African researchers said that variant B.1.351 does not appear to lead to more deaths or more severe cases of Covid-19.

Ravi Gupta, a professor of clinical microbiology at Cambridge University who was not involved in the study of South Africa’s AstraZeneca vaccine, said Sunday’s results underscored the need to update the current crop of Covid-19 vaccines against new variants. However, he said, AstraZeneca’s blows are expected to continue to provide some protection against the new strain. “We certainly still need to use vaccines to protect people from serious illness,” he said.

Concern about the South African variant and its impact on vaccine efficacy has focused on a mutation known as E484K. The researchers believe that this mutation makes it more difficult for antibodies to catch and neutralize the virus.

The same mutation was found in a separate variant discovered in Brazil. Researchers in the UK said earlier this month that they had discovered the E484K mutation in a small number of patients infected with another variant of the rapidly spreading coronavirus that causes infections there.

—Jenny Strasburg contributed to this article.

Write to Gabriele Steinhauser to [email protected]

Corrections and amplifications
Volunteers in a South African study with the AstraZeneca Covid-19 vaccine had a mean age of 31 years. An earlier version of this article incorrectly stated that they were on average 32 years old.