SINGAPORE — Fully vaccinated COVID-19 patients infected with the Delta variant experienced "significantly lower odds" of moderate or severe outcomes, according to a local study.
"Vaccination was associated with lower peak measures of systemic inflammation, fewer symptoms, including more asymptomatic infection, and better clinical outcomes," the study, posted last Saturday (31 July) on medical database medRxiv ahead of peer review, added.
Conducted by researchers across various medical institutions in Singapore, the study analysed 218 patients aged 18 and above who were infected with the Delta variant, which first originated in India, and were admitted across five hospitals or centres.
Of them, 84 had received an mRNA vaccine in Singapore, of whom 71 were fully vaccinated. A total of 130 patients were unvaccinated, while the remaining four received a non-mRNA vaccine overseas.
The study also found that initial Delta viral loads were similar for vaccinated and unvaccinated patients, in contrast to existing studies that showed lower viral load for vaccinated patients.
However, vaccinated patients appeared to clear the viral load at a faster rate, it noted.
The data also suggested that vaccination likely reduces secondary transmission, though the authors of the study stressed that this needs to be further analysed in larger community surveillance studies.
"Further studies should elucidate immunologic features driving vaccine-breakthrough infection to improve vaccine-induced protection," it added.
Since May, the Delta variant has become the dominant variant circulating in Singapore.
According to the Global Initiative on Sharing All Influenza Data (GISAID), the world's largest database of novel coronavirus genome sequences, the first case of the variant in Singapore was detected on 26 February.
The database showed that, as of 28 July, there are 1,975 cases of the Delta variant here.
Currently, only the Pfizer-BioNTech/Comirnaty and Moderna vaccines are part of Singapore's national vaccination programme. The Novavax vaccine, which has been approved for the programme, is expected to arrive by the year-end.
Vaccines by Sinovac and Sinopharm are available in Singapore via the Special Access Route (SAR) scheme. Those who have received the China-made vaccines locally are not included in Singapore's national vaccination numbers.
As of Sunday, 61 per cent of the population here have completed their full vaccination regimen, or received two doses of COVID-19 vaccines under the national vaccination programme, and 77 per cent have received at least one dose.
As of Sunday, 107,730 doses of Sinovac's CoronaVac vaccine have been administered to 74,935 individuals.
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