China National Pharmaceutical Group (Sinopharm) will need to assess results from overseas phase-3 clinical trials to decide whether its two-shot COVID-19 vaccine should be followed by a booster shot, a company executive said on Sunday.
Regulators and vaccine developers are looking at whether booster doses are necessary amid concerns that new variants of the coronavirus might weaken protection of vaccines designed against older strains.
“The preliminary results so far showed that the booster vaccination can effectively increase the neutralizing antibody titer and antibody persistence, and also effectively improve the vaccine’s ability to resist mutations,” Zhang Yuntao, vice president at China National Biotec Group, an affiliate of Sinopharm, said on Sunday.
“Is a booster shot needed? When will the booster be given? The answer should be based on the results of future phase-3 clinical studies,” Zhang said.
Antibodies triggered by two COVID-19 vaccine products from Sinopharm both have “pretty good” neutralizing effect on variants found in Britain and South Africa as well as a few others, Zhang said, citing results from lab tests using blood samples taken from clinical trial participants.
Lab testing was ongoing for variants found in Brazil and Zimbabwe, Zhang said.
The effect of antibodies induced by Sinovac Biotech’s vaccine declined against a variant identified in South Africa, while the effect against a variant found in Britain remained similar to that against the older variant in Wuhan, Gao Qiang, general manager at Sinovac unit Sinovac Life Sciences, said.
Sinovac is importing the variant from Brazil for vaccine research and development, and work tailored to the South Africa variant had started, Gao said.