A Covid-19 vaccine candidate developed by China appears to be safe and induces an immune response in healthy volunteers, according to preliminary study results.

Phase one/two trials of an inactivated SARS-CoV-2 vaccine candidate – CoronaVac – involved more than 700 healthy volunteers aged 18-59 recruited in China between April 16 and May 5.

According to results published in The Lancet Infectious Diseases, the vaccine appeared to be safe and well tolerated at all tested doses.

The most common reported side effect was pain at the injection site.

Within 14 days of the final dose, researchers detected robust antibody responses after two jabs of the vaccine candidate were given two weeks apart.

This was even the case for the lowest dose tested, three micrograms.

Researchers say antibody levels induced by the vaccine were lower than those seen in people who had been infected by and recovered from Covid-19.

But they add that the vaccine could provide protection from the virus.

The primary objective of the study was to evaluate the immune response and safety of the vaccine, and it was not designed to assess how effective it is at preventing infection with SARS-CoV-2, the virus that causes Covid-19.