China's Clover says its COVID-19 vaccines trigger "strong immune responses" in early trial

The vaccine candidates, one containing an adjuvant from GlaxoSmithKline and the other from Dynavax, induced strong immune responses including neutralizing antibodies and cell-mediated immunity in a Phase 1 clinical trial, Clover said. Adjuvants are ingredients that can boost immune responses.

While several vaccine candidates have shown promising trial results in recent weeks, health experts are encouraging the development of more vaccines to tackle a pandemic that has killed more than 1.5 million people globally.

"Based on the positive Phase 1 results reported and the unprecedented need for COVID-19 vaccines, Clover and its partners are confident to enter late-stage clinical development for both adjuvanted vaccines," the company said.

The vaccines did not trigger any serious adverse reactions on the 150 adult and elderly people that participated in the trial, the company said.

The candidate with the GSK adjuvant will begin a mid- to late-stage clinical trial this month, and the one with the Dynavax adjuvant is expected to start a separate phase 2/3 trial in the first half of next year.

Preliminary results showed that both candidates could be stored at temperatures of 2C to 8C (35.6F to 46.4F) for at least six months, Clover said. It also said the vaccine could remain stable at room temperatures or temperatures of 40C (104F) for at least one month.

Britain approved Pfizer Inc's COVID-19 vaccine on Wednesday, jumping ahead in a global race to begin the most crucial mass inoculation programme in history.

AstraZeneca Plc, Moderna Inc, and Russian researchers have also announced positive trial results in recent weeks.