The British drug company says its vaccine has “limited efficacy against mild disease” caused by the South African variant of the coronavirus.
The COVID-19 vaccine, developed by AstraZeneca and the University of Oxford, appeared to offer limited protection against mild disease caused by the South African variant of the coronavirus, a spokesman for the British medicine man said.
The statement on Saturday came after the Financial Times reported that the vaccine failed to prevent mild and moderate disease caused by the variant first identified in South Africa.
The paper cited early data from a study conducted by the University of Witwatersrand in South Africa and the University of Oxford, the findings of which will be published Monday.
The FT noted that none of the more than 2,000 mainly healthy and young study participants had been hospitalized or died. The findings have yet to be peer reviewed.
Commenting on the FT report, an AstraZeneca spokesperson said: “In this small phase I / II study, early data has shown limited efficacy against mild diseases, mainly due to South African variant B.1.351.
“However, we have not been able to properly establish its effect on severe illness and hospitalization, as the subjects were mainly young healthy adults.”
The company said it believed its vaccine could protect against serious illness as the neutralizing antibody activity was similar to other COVID-19 vaccines that have shown protection against serious illness.
The spokesperson also said AstraZeneca has started modifying its vaccine against the South African variant and will “make rapid progress in clinical development so that it is ready for delivery in the fall, should the need arise.”
While thousands of individual changes have occurred as the virus mutates into new variants, only a small minority is likely to be important or the virus to change in any noticeable way, according to the British Medical Journal.
Among coronavirus variants that are currently most concerning to scientists and public health experts are the so-called “South African”, “British” and “Brazilian” variants, which seem to be spreading faster than others.
Other vaccine developers, including Johnson & Johnson and Novax, have also said their vaccines showed decreased efficacy in clinical studies conducted in South Africa.
The Johnson & Johnson vaccine was 57 percent effective in South Africa, compared to 72 percent in the United States and 66 percent in Latin America. Novax, meanwhile, said its vaccine was 89.3 percent effective in a study conducted in the United Kingdom, but was only 50 percent effective in a study conducted in South Africa.
Moderna also reported a decreased immune response from its vaccine against the South African variant, and has said it will test a new booster shot targeting that variant.
Scientists say the mutations underscore the need to speed up vaccination efforts before new and even more dangerous variants emerge.