JAKARTA: China's Sinovac Biotech COVID-19 vaccine was 98% effective at preventing death and 96% effective at preventing hospitalisation among a group of inoculated Indonesian medical staff, a study conducted by the country's health ministry has found.

The findings were based on data from 120,000 healthcare workers in Jakarta who had received the vaccine between January and March this year, lead researcher and health official Pandji Dhewantara told a briefing on Wednesday.

Phase 3 trials of the vaccine, called CoronaVac, have produced varying results globally, but Pandji said the study found it also prevented symptomatic COVID-19 in 94% of the group.

"We see data from the taskforce that the incidence of morbidity and mortality for health workers tends to decrease," health ministry official Siti Nadia Tarmizi said at the news conference.

Separately, data from the Indonesian Medical Association showed the number of doctors dying from COVID-19 has dropped significantly since Indonesia’s vaccine rollout began this year.

In January, 64 doctors died due to the respiratory disease, the highest rate since the start of the pandemic, but that figure halved in February, and dropped to eight last month.

The promising findings come after Indonesia's phase 3 trials showed the vaccine was 65% effective. Trials in Turkey showed it was 91.25% effective, while researchers in Brazil said it was 50.4% effective at preventing symptomatic infections. 

CoronaVac is efficacious in preventing COVID-19 in adults under 60, but some quality data on the risk of serious adverse effects was lacking, World Health Organization experts found.

Indonesia has pushed hard to shore up vaccine deals to inoculate its large population but so far has largely relied on the Chinese vaccine due to global supply issues.

Almost 9 million people have been fully inoculated so far, according to the health ministry, with Indonesia aiming to vaccinate 181 million people by January, 2022.

Indonesia has suffered the highest number of cases and deaths from Sars-CoV-2 in Southeast Asia, with more than 1.7 million confirmed infections and 45,090 deaths, with the nation’s healthcare workers hard hit by the virus.

As of April 22, at least 900 Indonesian healthcare workers had died from COVID-19, according to Lapor-Covid-19, an independent coronavirus data initiative.