The British pharmacist says his vaccine has shown “limited effectiveness against mild disease” caused by the South African version of the coronavirus.
The COVID-19 vaccine developed by AstraZeneca and the University of Oxford appears to offer limited protection against mild diseases caused by the South African version of the coronavirus, said a spokesman for the British drug.
Saturday’s statement came after the Financial Times reported that the vaccine had failed to prevent a mild to moderate illness caused by the variant first identified in South Africa.
The newspaper cited early data from a trial conducted by the University of the Witwatersrand in South Africa and the University of Oxford, the findings of which are due to be published on Monday.
FT mentioned that none of the more than 2,000 participants, mainly healthy and young, were hospitalized or died. The findings have not yet been evaluated by colleagues.
Responding to the FT report, an AstraZeneca spokesman said: “In this low-phase I / II study, early data demonstrated limited efficacy against mild disease due mainly to variant B.1.351 in South Africa.
“However, we have not been able to properly establish its effect against severe illness and hospitalization, given that the subjects were predominantly healthy young adults.”
The company said it believes its vaccine could protect against severe disease, given that the antibody-neutralizing activity is equivalent to that of other COVID-19 vaccines that have been shown to protect against severe disease.
The spokesman also said that AstraZeneca has started to adapt its vaccine against the South African variant and “will advance rapidly through clinical development, so that it will be ready for autumn delivery, if needed.”
While thousands of individual changes have occurred as the virus moves into new variants, only a small minority is likely to be important or change the virus in an appreciated way, according to the British Medical Journal.
Among the coronavirus variants currently the most worrying for 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, also said their vaccines have shown low efficacy in clinical trials 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. Novax, meanwhile, said its vaccine was 89.3% effective in a study in the United Kingdom, but showed only 50% effectiveness in a study in South Africa.
Moderna also reported a reduced immune response from its vaccine against the South African variant and said it would test a new booster vaccine targeting that variant.
Scientists say the mutations underscore the need to accelerate vaccination efforts before new and even more dangerous variants emerge.