China-based Sinovac Biotech has reported positive data from healthy adults aged 60 years and above in Phase I/II clinical trials of its inactivated Covid-19 vaccine candidate, CoronaVac.

According to the results, the vaccine showed good safety and immunogenicity, comparable to that observed in healthy adults aged 18 to 59 years in the prior studies.

Conducted in China, the randomised, double-blinded and placebo controlled Phase I/II trials on elderly volunteers involved two-dose immunisation given 28 days apart.

The trials involved a total of 421 healthy adult volunteers aged between 60 and 89 years.

Sinovac noted that CoronaVac appeared to be well tolerated across low dose, medium dose and high dose groups. Investigators did not report any vaccine-related serious adverse event.

The seroconversion rate and GMT level for elderly participants were comparable to the 18 to 59 years healthy adults group. Based on the data, the medium dose was selected for Phase III trial.

For the medium dose, the seroconversion rate and GMT were 98% and 42.2, respectively, in elderly volunteers, and 97.4% and 44.1 in healthy adults.

Sinovac chairman, president and CEO Weidong Yin said: “I am very pleased that our vaccine candidate shows promising results, especially on elderly volunteers who are a highly vulnerable group impacted by the Covid-19 pandemic.

“As Sinovac is accelerating its vaccine development against the fast spread of the virus, we have completed the construction of our production facility and have commenced production of CoronaVac.”

In June this year, the company said that CoronaVac demonstrated favourable immunogenicity and safety profiles in healthy participants aged 18 to 59 years in Phase I/II studies.

Of the total 743 healthy adults, 143 were in Phase I and the remaining 600 in Phase II.

Later in July, the Brazilian National Regulatory Agency, Anvisa, approved a Phase III trial sponsored by Instituto Butantan to test the efficacy and safety of the Covid-19 vaccine candidate.