The British pharmaceutical company says its vaccine has shown “limited effectiveness against mild diseases” caused by the South African variant of the Coronavirus.
A spokesperson for the British pharmaceutical company said that the COVID-19 vaccine developed by AstraZeneca and the University of Oxford appears to provide only limited protection against the mild disease caused by the South African variant of the Coronavirus.
The statement came on Saturday after the Financial Times reported that the vaccine had failed to prevent mild and moderate disease caused by a variant that was first identified in South Africa.
The newspaper cited preliminary data from an experiment conducted by the University of the Witwatersrand in South Africa and the University of Oxford, and its results are due to be published on Monday.
And the Financial Times noted that none of the more than 2,000 healthy, young participants in the trial had not been hospitalized or died. The results have not been reviewed yet.
In response to the Financial Times report, an AstraZeneca spokesperson said: “In this small phase of trial 1/2, early data showed limited efficacy against mild disease mainly due to variant B.1.351 South Africa.
“However, we were not able to properly confirm its effect against severe disease and hospitalization given that the subjects were predominantly healthy adults.”
The company said it believed its vaccine could prevent severe disease, given that neutralizing antibody activity was equivalent to other COVID-19 vaccines that have proven to protect against severe disease.
The spokesperson also said that AstraZeneca has begun adapting its vaccine against the South African variant and will “rapidly advance through clinical development so that it will be ready for delivery in the fall if needed”.
While thousands of individual changes have emerged as the virus mutates into new variants, only a small minority is likely to be significant or alter the virus in a noticeable way, according to the British Medical Journal.
Among the variants of the Corona virus that concern scientists and public health experts currently are the so-called “South African”, “British” and “Brazilian” variants, which seem to be spreading more quickly than others.
Other vaccine developers, including Johnson & Johnson and Novax, said their vaccines have shown low efficacy in clinical trials conducted in South Africa.
The Johnson & Johnson vaccine was 57% effective in South Africa, compared to 72% in the United States and 66% in Latin America. Meanwhile, Novax said its vaccine was 89.3 percent effective in a trial in the United Kingdom, but only showed 50 percent effectiveness in a trial in South Africa.
Moderna has also reported a decreased immune response from its vaccine against the South African variant, and said it will test a new booster dose targeting that variant.
Scientists say the mutations underscore the need to speed up vaccination efforts before new, more dangerous variants emerge.