A double dose of China’s CoronaVac vaccine is 83.5% effective against symptomatic COVID-19, researchers say.

Their phase 3 trial included more than 10,000 people, aged 18 to 59, in Turkey who received either two doses of CoronaVac 14 days apart or an inactive placebo.

An immune response analysis of 981 participants who got the vaccine found that it triggered a strong immune response in 90%, the study authors said.

“In order to bring the COVID-19 pandemic under control, the world needs every single dose of safe and effective vaccines, and our results add important evidence of the safety and effectiveness of inactivated-virus vaccines,” said researcher Murat Akova of Hacettepe University Medical School, in Turkey.

In the trial, there were no severe adverse events associated with the vaccine, and most adverse events (90%) were mild. They included fatigue, injection site pain and muscle aches.

The trial was conducted between Sept. 14, 2020 and Jan. 5, 2021. The preliminary findings were published July 8 in The Lancet and are scheduled to be presented during a virtual meeting of the European Congress of Clinical Microbiology & Infectious Diseases, held July 9 through 12.

The researchers said further study is needed to confirm the vaccine’s long-term effectiveness. That’s because this trial had a short follow-up period, relatively young and low-risk participants, and it took place before variants of concern appeared.

Developed by Sinovac Life Sciences, CoronaVac uses an inactivated, harmless virus that prompts the immune system to produce antibodies, according to a journal news release.

The vaccine has been approved for emergency use in 22 countries, and has been in phase 3 trials in Brazil, Indonesia, Chile and Turkey since mid-2020.

Akova said CoronaVac has an important advantage over some other coronavirus vaccines.

“One of the advantages of CoronaVac is that it does not need to be frozen, making it easier to transport and distribute,” Akova said. “This could be particularly important for global distribution, as some countries may struggle to store large amounts of vaccine at very low temperatures.”

Maheshi Ramasamy of the University of Oxford in England, and Lucy Jessop of the National Immunisation Office of the Health Service Executive in Ireland, wrote an editorial published along with the study results.

The findings “suggest that two doses of CoronaVac have robust efficacy (within the WHO target product profile for SARS-CoV-2 vaccines) and acceptable tolerability when administered with a 14-day interval,” they wrote.

The editorialists noted that the availability of CoronaVac in single-dose vials reduces waste and makes it easy to administer.

“CoronaVac is another useful tool in the global fight against COVID-19, although more data are needed on its efficacy against emerging variants and on its duration of protection across different age groups and geographical settings and in the presence of comorbidities,” the editorial concluded.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19 vaccines.

SOURCE: The Lancet, news release, July 8, 2021

Source: HealthDay