People who are vaccinated against COVID-19 with BioNTech's vaccine were found to have "substantially higher" levels of antibodies than those who received Sinovac's jab, the  on Saturday, citing a Hong Kong study.

Some who received the Sinovac vaccine might need a third booster shot as well, the newspaper said, citing lead researcher Professor Benjamin Cowling, an epidemiologist with the University of Hong Kong (HKU).

The government-commissioned study was conducted by HKU's school of public health and involved tracking the antibody responses of 1,000 people who received either vaccine, the report added.

Earlier this week, officials in Indonesia warned that more than 350 medical workers have caught COVID-19 despite being vaccinated with Sinovac and dozens have been hospitalized, raising concerns about its efficacy against more infectious variants of the virus.

Earlier in June, Uruguay released real-world data on the impact of Sinovac Biotech's COVID-19 vaccine among its population that showed it was over 90 per cent effective in preventing intensive care admissions and deaths. 

The Uruguay government also studied the effectiveness of the Pfizer/BioNTech's vaccine among 162,047 health workers and people over 80 years old, and said the shot was 94 per cent effective at preventing intensive care unit admissions and deaths, and reduced infections by 78 per cent.

(Reporting by Nandakumar D in Bengaluru; Editing by Raju Gopalakrishnan)