People who received Sinovac Biotech shots are excluded from Singapore's count of total vaccinations against Covid-19, said officials in the city state, citing inadequate efficacy data for the Chinese-made vaccine, especially against the contagious Delta variant.

"We don't really have a medical or scientific basis or have the data now to establish how effective Sinovac is in terms of infection and severe illnesses on Delta," Health Minister Ong Ye Kung said during a media briefing.

Reuters reports that only people who participated in the national immunisation programme, which currently uses the Moderna and Pfizer-BioNTech/Cominarty shots, are counted in the tally for vaccinations.