More than 350 Indonesian healthcare workers vaccinated with China's Sinovac vaccine got COVID-19 and dozens are hospitalized, raising questions about the vaccine's efficacy on variants

• The vast majority of Indonesia's healthcare workers received China's Sinovac vaccine.
• A study in the country found the vaccine was very effective at curbing hospitalization and death.
• Over 350 healthcare workers caught COVID-19, most likely the Delta variant, Reuters reported.
• See more stories on Insider's business page.

More than 350 Indonesian healthcare workers who were vaccinated with China's Sinovac vaccine caught COVID-19, , Reuters reported.

While the majority of those who tested positive for the coronavirus were asymptomatic, dozens needed hospital care.

Badai Ismoyo, head of the health office in the district of Kudus in Central Java, told the outlet that more than 90% of the facility's beds are occupied. 5,000 healthcare workers are currently dealing with the outbreak, about 7% of whom have become infected.

It's likely that the outbreak is fueled by the more transmissible Delta variant, which originated in India. The number of workers testing positive has prompted officials to question how effective the Sinovac vaccine is against variants.

The Delta variant can also result in more serious illness. It may also be able to evade protection from existing vaccines, as Insider's Aria Bendix reported.

"The data shows they have the Delta variant (in Kudus) so it is no surprise that the breakthrough infection is higher than before, because, as we know, the majority of healthcare workers in Indonesia got Sinovac, and we still don't know yet how effective it is in the real world against the Delta variant," Dicky Budiman, an epidemiologist at Australia's Griffith University told Reuters.

Last month, Indonesian health officials said the Sinovac vaccine was estimated to be 98% effective at preventing death and 96% effective at preventing hospitalization.

The statistic came after 128,000 healthcare workers who were vaccinated were monitored between January and March and it was found that 94% of them hadn't caught symptomatic COVID-19.

The efficacy rate from trials in Brazil was lower than that found by Indonesian officials, at 50.7% effective against symptomatic COVID-19.

The study and trial did not look at the Delta variant.

Indonesia recorded over 1.9 million infections with 53,000 deaths since the start of the pandemic. Doctors and nurses accounted for close to 950 deaths. They were the first to receive the Sinovac vaccine in January.