Sinopharm’s COVID-19 booster shot generated “significantly lower” levels of antibodies against the omicron variant, in a study offering further clues on how one of the world’s most widely used vaccines stands up against the new strain.
A study of 292 healthcare workers given a booster 8 to 9 months after their second dose found that omicron caused a 20.1-fold reduction in neutralising antibodies, compared to the performance against the original Wuhan strain.
Researchers at Shanghai Jiao Tong University School of Medicine said their analysis only assessed one part of the immune system’s response and the vaccine’s efficacy against omicron still remains unclear.
The findings, which have yet to be peer-reviewed, will fuel concerns that the inactivated vaccine from the Chinese developer may offer inadequate protection against omicron infection even after a third dose, at a time when many countries are rolling out booster campaigns.
Omicron, which infects much faster than the delta variant, has rapidly spread to more than 77 countries in less than one month since first being identified in southern Africa. A growing body of evidence from various studies around the world indicates booster shots could be vital in neutralising omicron. On Monday Moderna Inc. said a 50 microgram third dose of its vaccine produced a 37-fold increase in neutralising antibodies.
Earlier this month initial lab findings showed rival Sinovac Biotech Ltd.’s vaccine—one of the most widely used in the world along with the Pfizer-BioNTech shot—didn’t provide sufficient antibodies after two doses against omicron and boosters will likely be needed.
