BEIJING — A China-developed recombinant protein COVID-19 vaccine that requires to be administered in three shots has been made available in Beijing.

The vaccine (CHO Cells) was jointly developed by the Institute of Microbiology under the Chinese Academy of Sciences and Anhui Zhifei Longcom Biopharmaceutical Co Ltd. Starting on May 27, the researchers from the institute have received the first jab in Beijing's Haidian district.

China issued emergency use authorization of the vaccine on March 10, and people from many provinces including Anhui and Hubei have been vaccinated since then. On May 3, the first batch of the vaccine was rolled off the production line in Beijing, according to the institute.

The results of phase-2 trials, which involved people aged between 18 and 59, show that 83 percent of the participants produced neutralizing antibodies after two doses of the vaccine, and 97 percent produced neutralizing antibodies after three doses.

The early-stage trials conducted among people aged 60 and above show that the seroconversion rate of neutralizing antibodies reached 95 percent after three doses, with no serious adverse reactions related to vaccination.

The level of neutralizing antibody elicited by the vaccine is comparable to other COVID-19 recombinant protein vaccines and mRNA vaccines globally, the institute said in a statement.

Recombinant protein vaccine does not need a high-grade biosafety laboratory for manufacture, and can quickly achieve large-scale production. It is more cost-efficient and easier to store and transport, the vaccine maker said.