Health Minister Ong Ye Kung has warned against using another person's vaccination certificate in order to be allowed to dine at restaurants, saying the authorities are aware this is happening.
In a Facebook post yesterday, Mr Ong said: "The authorities will enforce against this, and offenders will face (a) severe penalty. It is not worth it. Take a PET if you have to attend a dinner or event."
A PET refers to the pre-event Covid-19 test, which costs about $20 and is valid for 24 hours.
Under the gradual easing of rules which began on Tuesday, persons who have not been fully vaccinated are required to take a PET to dine in a restaurant or foodcourt.
This differentiated approach is aimed at protecting persons who have not been vaccinated, as the consequences of their contracting the virus can be much more severe.
Yesterday, Mr Ong added that those with a negative test result are still not protected from infection, and should be careful.
The Ministry of Health had said in a separate announcement on Tuesday that those who have recovered from Covid-19 in the last 270 days will still need a valid pre-event test (PET) exemption notice if they wish to dine in at a food and beverage establishment.
It said recovered individuals are not automatically considered to be in the same category as fully vaccinated individuals.
People are considered fully vaccinated two weeks after receiving the full regimen of the Pfizer-BioNTech/Comirnaty, Moderna, or any vaccine on the World Health Organisation's (WHO) Emergency Use Listing, such as AstraZeneca, Janssen, Sinopharm, or Sinovac.
The multi-ministry task force tackling Covid-19 had noted last Friday that unvaccinated individuals with a valid negative PET test, or recovered individuals, are considered of similar lower risk as fully vaccinated persons, and may dine in at eateries in groups of up to five persons, among other perks.
The ministry said this week that residents who were vaccinated overseas with any of the vaccines under the WHO's list also have to provide documentary proof and take a blood test at an approved provider to confirm that their vaccinations have been effective.
Upon a positive serology test, their vaccination records will be updated in the National Immunisation Registry (NIR) and reflected on the TraceTogether (TT) and HealthHub apps. A separate process is being worked out for short-term visit pass holders who were vaccinated abroad so that their vaccination status can be included in the NIR.
"Hard copies of overseas vaccination certificates will not be accepted for the vaccination-differentiated safe management measures," said the ministry.
"This is because it will be difficult for individual establishments to verify the authenticity of these certificates which are issued in different formats and languages."
As part of the easing of measures since Tuesday, people can dine at hawker centres and coffee shops regardless of their vaccination status, but only in groups of two.
Coffee shops include food and beverage establishments with either a coffee shop, eating house or a canteen licence issued by the Singapore Food Agency, MOH said.
"We encourage unvaccinated individuals who dine at such locations to vigilantly maintain hand hygiene, and not to linger after their meals, in order to reduce their risk of contracting Covid-19."
MOH also said those who received the Sinovac vaccine here can access their vaccination records on the HealthHub app.
All Singapore residents who got the Pfizer-BioNTech/Comirnaty or Moderna jabs would have their records updated and reflected on both HealthHub and TT apps.
As for those who took other vaccines on the WHO list overseas, their record will be uploaded on HealthHub for now. Mr Ong said: "We are working on uploading to TT app as well, and this will be ready by end-August."