SINGAPORE: The Expert Committee on COVID-19 (EC19V) does not recommend that people aged 60 to 79 years take a second booster shot, but they can take the jab if they wish to, said Director of Medical Services Kenneth Mak on Friday (Apr 22).
The second booster vaccine dose should be administered about five months after receiving the first booster. This timing is based on Singapore’s local data, which shows that waning of vaccination protection takes place after 150 days, said Dr Mak at a virtual press conference held by the COVID-19 multi-ministry task force.
Those in the 60 to 79 age group can receive their second booster by walking into any vaccination centre offering mRNA vaccines before 7pm.
This is in addition to the earlier recommendation of a second booster for some groups – those aged 80 and above, residents of aged care facilities, and the medically vulnerable.
Dr Mak said local data shows that vaccine effectiveness against severe disease remains high for some time after primary vaccination and a booster, but there is a difference based on age groups.
The vaccination effectiveness for those older than 60 remains well above 80 per cent, and in some cases reaches 90 per cent at the 120- to 180-day mark after booster vaccination.
“This affirms the importance then of having up-to-date vaccinations to reduce the risk of getting severe infections and dying from COVID-19,” he said.
The data also shows some benefit of a second booster dose in those aged 60 to 79, but not to the same “great extent” as in those above 80. This is because the incidence of severe infection in these age groups is lower compared to octogenarians, he said.
In even younger age groups, between the ages of 12 to 60 years, data suggests that the second booster dose is “not as beneficial at this time” as the risk of getting severe infection for them is much lower, unless they already have chronic medical conditions.
Dr Mak said that there was some overall boosting against all infections but the effect waned rapidly after about two months.
“So if we need to provide the second booster dose for the younger population, this is more appropriate as a strategy to augment immune protection in a time when we are experiencing a new wave of a highly transmissible or highly virulent novel VOC (variant of concern) rather than at a time where the situation is improving,” Dr Mak said.
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BOOSTER DOSES FOR RECOVERED PERSONS
The EC19V has also recommended a booster dose for recovered persons aged 12 and above who have completed their primary vaccination, in view of waning immunity.
This booster should not be delayed beyond nine months after completing the primary vaccination series, and should be received at least 28 days after the infection.
From Jun 1, these recovered persons will need to receive the booster dose within nine months of their last primary vaccination dose, in order to maintain their vaccinated status.
Individuals may walk into any vaccination centre, before 7pm, to receive their booster dose.
Dr Mak said this recommendation takes into account recent evidence that the immune protection in recovered people can vary significantly between individuals and wanes over time.
“We cannot assume that a recovered individual will have enhanced immune protection after their recovery from an infection compared to a non-infected individual at a comparable time point following their vaccination,” he said.
“Both local and international experience has shown that booster vaccination is safe for recovered persons and will help to maintain a high level of protection in them against severe infection.”
The EC19V is in the midst of reviewing the data from vaccinating children below the age of 18, Dr Mak added.
“We need to carefully study the data to determine whether recommendations need to be made to offer booster vaccinations for children and MOH (Ministry of Health) will make future announcements on this when our review is completed,” he said.
MOH also said that booster vaccination for all recovered migrant workers in dormitories and non-dormitory dwelling work-permit holders in the Construction, Marine, Processing sector will be scheduled and announced later.
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SECOND BOOSTER SHOT NEEDED “SOONER OR LATER”
Health Minister Ong Ye Kung said that further booster shots will be required as COVID-19 becomes endemic – the only question being that of timing. This is the consensus among scientists around the world, and MOH and the EC19V agree, he said.
“Administer too early and chances are it will be wasted, administer too late and damage would have already been done,” he said.
To determine a suitable time to administer a further booster, MOH is closely monitoring two indicators, he said.
One was whether subsequent Omicron or new variant waves break out in other countries, which would be a sign that a new wave may emerge in Singapore. The country should then roll out a second booster before that happens, said Mr Ong.
A second indicator is the level of vaccine protection against severe illness for those who have already had their first booster – which many scientists think can last one to two years, or even longer.
“We will watch out for early signs of waning of vaccine efficacy against severe illness, which will indicate the need for a second booster,” said Mr Ong.
As for which vaccines to use for a second booster, it will depend on the nature of the new variant of concern.
If it is a derivative of the Omicron variant with similar characteristics, then it’s likely that the current vaccines will continue to confer good protection, he said.
However, if the new variant is more dangerous, then it may require a different strategy, said Dr Ong. A more deadly variant may also mean the return of safe management measures like contact tracing and testing.
A “worst-case scenario” would be a variant that is more deadly and more transmissible than Omicron, he warned.
“We may then need to hunker down for six months or more, while scientists develop a new variant-specific vaccine. And this is one of the worst-case scenarios that we need to be psychologically prepared for.”