Sinovac and Sinopharm less effective than Pfizer in fighting COVID: Singapore study

Staff Writer
·Editorial team
·2 min read
Nurl Anisah, a nurse at StarMed Specialist Centre, prepares to administer the Sinovac vaccine to a patient, in Singapore July 13, 2021. REUTERS/Caroline Chia
A nurse prepares to administer the Sinovac vaccine to a patient in Singapore. (Reuters file photo)

SINGAPORE — Those who are vaccinated with two China-made COVID-19 vaccines are more likely to be infected with the virus, compared with those who are inoculated with the Pfizer-BioNTech vaccine.

These were among the findings published on Tuesday (12 April) in a study by a group of Singapore infectious disease experts including National Centre for Infectious Diseases (NCID) executive director Leo Yee Sin, Ministry of Health (MOH) Communicable Diseases Division director Vernon Lee and NCID Infectious Disease Research and Training Office director David Lye.

The study compared the efficacies of mRNA and inactivated whole virus COVID-19 vaccines, such as Sinovac-CoronaVac and Sinopharm, in the same population to derive findings "useful for guiding policy recommendations to prevent infection and reduce strain on the healthcare system".

Sinovac and Sinopharm recipients are 2.37 and 1.62 times more likely to be infected, respectively, compared with those who receive Pfizer shots.

In addition, Sinovac and Sinopharm recipients are around five times and 1.58 times more likely to develop severe disease, respectively, compared with Pfizer recipients.

But Moderna recipients are 0.84 time less likely to be infected and 0.42 time less likely to develop severe disease, compared with those who have the Pfizer vaccine.

Both mRNA vaccines and inactivated whole virus vaccines "provide sufficient protection against COVID-19 severe disease" and vaccination remains a key strategy against the pandemic, according to the study.

A total of 2.7 million adults aged 20 and above between 1 October and 21 November 2021 who had received two doses under the national vaccination drive in Singapore were assessed in the study.

Of them, 74 per cent received the Pfizer vaccines, 23 per cent were administered with Moderna, two per cent took Sinovac, and one per cent had Sinopharm.

The group included 107,220 adults who were confirmed by polymerase chain reaction (PCR) tests to be infected with COVID-19 and 644 who developed severe disease over the period of the study.

As of Tuesday, 92 per cent of Singapore's total population have completed the full vaccination regimen, while 73 per cent have received their booster shots.

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