The guidance follows news of South Africa halting rollout of AstraZeneca’s vaccine because early findings showed a marked reduction in protection against mild-to-moderate illness amid a variant strain.
“Even if there is a reduction in the possibility of this vaccine having a full impact in its protection capacity, especially against severe disease, there is no reason not to recommend its use, even in countries that have the circulation of the variant,” Dr. Alejandro Cravioto, chair of the Strategic Advisory Group of Experts on Immunization (SAGE), a panel of experts advising the WHO, said during a briefing.
The AstraZeneca vaccine was found to be about 75% effective against a separate strain circulating in the U.K., called B.1.1.7.
Prof. Shabir Madhi with the University of the Witwatersrand presented findings to South African health officials on Sunday, on a Phase 2 trial with 2,000 healthy participants aged 18 to 65, showing a vaccine efficacy of 10.4% against mild-to-moderate illness amid the variant. Before the variant emerged, the vaccine was about 75% effective, Madhi said.
However the trial design didn’t assess for the vaccine’s effectiveness against severe disease (most of the participants were young and healthy). Therefore, scientists still remain hopeful that the vaccine may offer protection against severe courses of disease amid a variant called B.1.351.
South Africa’s Health Minister Dr. Zweli Mkhize said Wednesday the country would switch to the Johnson & Johnson vaccine for health care workers and, at least for now, not use Oxford-AstraZeneca’s.
AstraZeneca has already voiced confidence in its vaccine to protect against severe disease. A company spokesperson previously told Fox News, in part, “We believe our vaccine will protect against severe disease caused by the new B.1.351 variant, as neutralising antibody activity is equivalent to that seen with other COVID-19 vaccines that have demonstrated activity against more severe disease, and particularly when the dosing interval is optimised to 8-12 weeks.”
During the WHO briefing Wednesday, Cravioto also said the group of experts advises using the vaccine for all adults aged 18 up, including those 65 and older, though some countries like Germany and France specifically recommended against this, citing insufficient data.
Additionally, SAGE recommended spacing the jabs 8 to 12 weeks apart for an optimal immune response. A previous study by Oxford University found that the vaccine actually offered more protection when the first and second doses were spaced further apart. Researchers had said the vaccine was 76% effective after the first dose, and it maintained this protection from 22 days to 90 days after the first dose. However, the vaccine was even more effective when administered after longer intervals between the first and second dose, at 82% after a gap of 12 weeks or more.
Dr. Soumya Swaminathan, chief scientist with the WHO, said the AstraZeneca vaccine is key because it comprises one of the largest shares of vaccines in COVAX, an initiative co-led by WHO focused on vaccine equity, expediting vaccines to developing countries.
Swaminathan said the AstraZeneca vaccine is easier to use and can be stored at ordinary refrigerator temperatures. AstraZeneca has already agreed to supply 170 million doses of its vaccine to the COVAX initiative, which Swaminathan said could begin rollout later this month. Experts say widespread vaccination will help prevent emerging mutations in coronavirus strains and ultimately conquer the pandemic.
The Associated Press contributed to this report.