A third shot of Sinopharm’s Covid-19 vaccine leads to a rebound in antibody levels that drop months after a second dose, a small-scale Chinese study showed.

Sinopharm’s Covid-19 vaccine elicited weaker antibody responses against the Delta variant, based on the first published study of its effect against the more contagious version.

Two Covid-19 vaccines from China’s Sinopharm showed more than 70 percent efficacy against symptomatic cases, but it remains unclear how much protection they provide against severe or asymptomatic cases, according to the first detailed result of a large late-stage study published to the public.

The World Health Organization (WHO) approved for emergency use a Covid-19 vaccine from China’s state-owned drugmaker Sinopharm on May 7, bolstering Beijing’s push for a bigger role in inoculating the world.

The World Health Organization expects to release its assessments for emergency use listing of the two main Chinese vaccines for Covid-19 as well as the Moderna shot by the end of next week, WHO Assistant Director-General Mariangela Simao said on April 30.

Leaked documents from provincial and municipal governments in China reveal a slew of previously unreported severe adverse events related to Covid-19 vaccines made and administered in China.

Technical experts at the World Health Organization (WHO) will review on April 26 Chinese drugmaker Sinopharm’s Covid-19 vaccine for possible emergency use listing, to be followed by the Sinovac jab on May 3, the agency said on April 22.

As the world awaits the production and distribution of hundreds of millions of doses of COVID-19 vaccines that have been granted emergency use authorization, biopharmaceutical companies and manufacturers are developing the next wave of vaccines and therapeutics to combat the pandemic.

The World Health Organization listed AstraZeneca’s Covid-19 vaccine for emergency use, widening access in the developing world, while sources said the EU is in talks with Moderna on buying more vaccines.

China approved a Covid-19 vaccine developed by an affiliate of state-backed pharmaceutical giant Sinopharm on Dec. 31, the country’s first approved shot for general public use as it braces for increased transmission risks over winter.