SINGAPORE — The Ministry of Health (MOH) will be conducting further studies to monitor and review the extent and duration of immunity provided by the COVID-19 vaccines, said Senior Minister of State for Health Janil Puthucheary in Parliament on Monday (5 April).
"This includes collecting selected post-vaccination samples from groups such as healthcare workers, frontline staff, and seniors to monitor the persistence of antibodies up to 24 months," Dr Janil replied, in response to questions by Members of Parliament (MPs) on the progress of Singapore's vaccination drive.
More details on the studies will be shared once they are completed, said Dr Janil, adding that there are no plans to serologically test those who have been vaccinated, which are currently in line with international practices.
Trial studies have shown that Pfizer-BioNTech and Moderna COVID-19 vaccines – the only two vaccines approved for use here – proved to be effective at least six and three months, respectively. Immunity from Moderna's vaccine should last at least a year, said the company a month after the study results were released in December last year.
In response to a follow-up question by Bukit Batok SMC MP Murali Pillai on the reasons for not serologically testing those who have been vaccinated, especially given the different coronavirus variants, Dr Janil said authorities will conduct these studies before making a decision about assessing what is happening in the population.
"For most vaccinations previously, that hasn't been the approach – population-wide antibody (tests). It's also logistically very difficult and places a burden on the population. So we need to be sure that it's useful and necessary before we would do such a thing," he added.
On the issue of protection against the different variants, Dr Janil said that essaying a set of antibodies to a prior vaccination is not necessarily useful to inform the clinical risks for a new variant that might not be around when the vaccination was delivered.
"I think there are two separate issues. The issue of various virus variants is being closely studied by our experts as well as international experts, and the matter of if, when, whether we should be doing serology and antibody testing is also being studied," he added.
During a COVID-19 press conference on 24 March, MOH Deputy Director of Medical Services Kenneth Mak said there is no "routine requirement" for those who have been vaccinated to get themselves tested to determine that they have the relevant antibodies.
The associate professor had noted that, however, there would be instances where serological investigations might be carried out for individuals who have been vaccinated to test for antibodies, such as if they are showing symptoms of respiratory infection.
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