South Africa halted the planned rollout of the COVID-19 vaccine developed by AstraZeneca and Oxford University after data showed it gave minimal protection against mild infection from one variant of the virus found in the country.
* Scientists say it is different from other variants circulating in South Africa because it has multiple mutations in the important “spike” protein that the virus uses to infect human cells.
* The 501Y.V2 variant, part of the B.1.351 lineage, is about 53% more transmissible than earlier variants of the virus, research shows.
* Drugmakers including Pfizer/BioNTech , Moderna, AstraZeneca are testing whether their vaccines protect against the variant.
The study was based on 2,026 volunteers who were on average 31 years old – half were given a placebo. Mild disease was defined as at least one symptom of COVID-19.
Prior to widespread circulation of the more contagious variant, the vaccine was showing efficacy of around 75%, researchers said.
In a later analysis based mostly on infections by the new variant, there was only a 22% lower risk of developing mild-to-moderate COVID-19 versus those given a placebo.
Although researchers said the figure was not statistically significant, due to trial design, it is well below the benchmark of at least 50% regulators have set for vaccines to be considered effective against the virus.
The study did not assess whether the vaccine helped prevent severe COVID-19 because it involved mostly relatively young adults not considered to be at high risk for serious illness.
AstraZeneca said it believed its vaccine could protect against severe disease given that the neutralising antibody activity was equivalent to that of other COVID-19 vaccines that have demonstrated protection against severe disease.
The British partners aim to produce a next generation of COVID-19 vaccines that will protect against variants as soon as the autumn.
REACTIONS SO FAR:
* Some scientists say it may be better to roll out the AstraZeneca shot in South Africa to provide some protection rather than waiting for the delivery of other shots.
Andrew Pollard, chief investigator on the Oxford vaccine trial, said the data confirms that the coronavirus will find ways to spread, but shots could help ease the toll on health care systems if they prevent severe disease.
* While it was only a small sample size and in low-risk volunteers, the data highlights the need to determine if the shot is effective in prevent more severe illness, the WHO said on Monday.
Additional studies are needed to confirm the optimal vaccination schedule, it said.
“What these results tell us is that we need to do everything we can to reduce circulation of the virus and delay mutations that may reduce the efficacy of existing vaccines,” it said.
“It also seems increasingly clear that manufacturers will have to adjust to the COVID-19 viral evolution, taking into account the latest variants for future booster shots.”
Emma Hodcroft, a researcher at the University of Bern: “If the vaccine is less effective, there would be a concern that any partial protection it may offer could allow mutations that confer an advantage by evading that immunity to rise to prominence, perhaps leading to variants that are completely escaped from vaccine-immunity.”
Preliminary data, which have yet to be peer reviewed and involve a small number of patients, show the vaccine may be less able to protect against infection with the South African variant of the virus.
NOVAVAX AND J&J:
Clinical trial data on COVID-19 vaccines developed by Novavax and Johnson & Johnson have found the South African coronavirus reduced their ability to protect against the disease.