SINGAPORE: A Singapore study has found that people who received two doses of the Sinovac-CoronaVac COVID-19 vaccine have lower protection against severe disease from the Delta variant, compared to those who took two doses of the mRNA vaccines available here.
This is according to a recent study by the National Centre for Infectious Diseases (NCID) and the Ministry of Health (MOH), which is based on local data covering 1.25 million people.
The effectiveness of two doses of the Sinovac vaccine was 60 per cent against severe disease, said NCID and MOH in a media release on Wednesday (Dec 15).
This is lower than that of the Pfizer-BioNTech/Comirnaty vaccine - at 90 per cent effectiveness - and the Moderna shots, at 97 per cent.
"These results support the need for three doses of Sinovac-CoronaVac vaccines as a primary series to attain better protection against severe disease, defined as requiring oxygen, intensive care unit (ICU) care and death due to COVID-19," said NCID and MOH.
It was announced in October that the Sinovac vaccine would be included in Singapore's national vaccination programme as a three dose regime.
From Jan 1, only those who have received three doses of the Sinovac or Sinopharm vaccines will be considered fully vaccinated.
The study, which was conducted from Oct 1 to Nov 21, involved people aged 40 and above who received two doses of the vaccines under the national vaccination programme.
Of the 1.25 million people covered in the study, 62,900 had COVID-19 and 1,710 were considered severe cases.
Most of them - 73.7 per cent - took the Pfizer-BioNTech/Comirnaty vaccine, while 23.9 per cent received the Moderna shots and 2.4 per cent received the Sinovac vaccine.
"The analysis accounted for differences in age, gender, race, housing type and the daily differences in infection rate," said NCID and MOH.
They recommended that those who have already received two doses of the Sinovac vaccine get a dose of an authorised mRNA vaccine as the third dose of their primary vaccination series.
"Otherwise, they should complete their primary series with a third dose of the Sinovac-CoronaVac."
NCID and MOH noted that the recommendation is substantiated by international findings.
"Based on preliminary data from Chile, persons who received the Pfizer-BioNTech/Comirnaty vaccine as the third dose after two doses of the Sinovac-CoronaVac vaccine had a 95 per cent reduction in the risks of infection," they said.
"In contrast, the risk reduction in persons who received Sinovac-CoronaVac as the third dose was 71 per cent.
"The antibody rise was also observed to be around 27 times higher when the Pfizer-BioNTech/Comirnaty vaccine was received as the third dose compared to if Sinovac-CoronaVac vaccine was received."
Authorities said they will continue to monitor the effectiveness of the mRNA and non-mRNA vaccines, including how they are enhanced by a third dose or a booster dose.
"In the meantime, all persons who are eligible for their boosters should get boosted when it is offered to them," said MOH and NCID.
https://www.channelnewsasia.com/singapor...oh-2381976