BEIJING (Reuters – The Sinopharm subsidiary announced that two COVID-19 candidate vaccines, which were developed by China National Biotec Group (CNBG), to combat the Omicron variant of the Omicron virus, have been cleared for clinical trials in Hong Kong as boosters.

Researchers around the world are frantically trying to find out how to upgrade Omicron vaccines. Data suggests that older strains of Omicron vaccines have weaker ability to neutralize this highly transmissible variant.

Both candidates contain inactivated Omicron viruses and are similar to those used in China by Sinopharm. The tests will take place on adults who have received at least two doses of vaccine, CNBG stated in a statement.

It didn’t specify what vaccine products trial participants received prior to receiving experimental boosters, nor how many subjects were recruited.

A Chinese study https://www.medrxiv.org/content/10.1101/2022.02.19.22271215v1.full.pdf showed that a fourth dose of BBIBP-CorV, an existing Sinopharm vaccine, did not significantly lift antibody levels against Omicron when administered six months after a third booster dose to a regular two-dose regimen.

Researchers said that while the fourth dose restored antibody levels to levels similar to those seen after the first dose, future boosters might be better.