Original post from 17th February:
In Singapore, receiving a primary course of covid vaccination may not be enough to qualify you as "fully vaccinated" (for most intents and purposes).
You are only considered "fully vaccinated" for the purpose of vaccine-differentiated safe management measures (VDS) for 270 days after the last dose of your primary vaccination series.
For VTL purposes (Vaccinated Travel Lane - i.e. to enter the country without quarantine) you only need "the full regimen of WHO EUL vaccines at least two weeks before arrival in Singapore" (i.e. no booster is needed). But VTL requirements are different from VDS requirements.
The first time you enter Singapore you get temporary "vaccinated" status for 30 or 180 days. But this will not be renewed when you exit and re-enter. You are supposed to register your overseas vaccination into the National Immunisation Registry at any PHPC clinic in Singapore (you may need to take a serology test, especially if your overseas vaccination record is not digitally verifiable).
If you haven't gotten and won't get a booster, you can still be considered fully vaccinated if you have previously gotten covid, since "There are currently no recommendations for the following groups of persons who had completed their primary vaccination series to receive booster vaccination: Recovered individuals* who have completed their primary vaccination series".
However, if you got covid when you were outside of Singapore, to prove that you had previously gotten it, you'll need to take an Anti-N serology test from any PHPC clinic in Singapore. A positive PCR test from overseas is not accepted. On the upside, it's only $48.15 at Raffles Medical (https://www.raffleshealth.com/total-antibody-n-protein-tanp-test.html). But note that up to 1 in 5 who get covid won't have their infection show up on this test.
The full response from MOH to an enquiry I made about overseas infection and exemption from booster requirements in Singapore is below:
"We refer to your enquiry made to the Ministry of Health website on 13 February 2022...
We wish to inform you that all individuals who have been fully vaccinated overseas with any vaccines approved under the WHO Emergency Use Listing (EUL) can get their overseas vaccination records ingested into the National Immunisation Registry (NIR). This includes Singaporean Citizens (SC), Singapore Permanent Residents (PR), Long-Term Pass Holder (LTPH) (e.g. Long-Term Visitor Pass, Work Permit, Employment Pass, S Pass, Dependent Pass, Student Pass) and Short-Term Pass Holders (STPH).
This can be done at any PHPC clinic participating in onboard on this initiative. You can also refer to https://phpc.gov.sg/ for a listing of clinics who may provide such services. We advise you to call ahead and check. Once they clinic has review the your overseas vaccination documentation - either the original hard copy vaccination certificate or digital vaccination certificate (with translated document where applicable) and serology test result is positive, they will update your vaccination records into the NIR. If you are a holder of vaccination certificate from selected countries, you may be exempted from serology testing. The Healthcare provider will scan your certificate to verify authenticity and update into the NIR accordingly. You may refer to our website for the list of counties whose vaccination certificate is eligible for exemption for serology testing here: https://www.moh.gov.sg/covid-19/vaccination/faqs---post-vaccination-matters. Do note that the charges involved are borne by the individual.
Separately, to ingest overseas COVID-19 records, you may request for an Anti-N serology test from any PHPC clinic as mention above. Please call in advance to check that the clinic is able to support serology testing. Thereafter, upon receiving positive results for your serology test which would indicate a past infection, your vaccination status should be updated. Do note that all charges are to be borne by the individual.
You may refer to our website https://www.moh.gov.sg/covid-19/vaccination/faqs---booster-doses for booster recommendation for recovered individuals."
Actually, it looks like tourists or other people without status in Singapore are not able to get their vaccination records updated in the National Immunisation Registry. So these people will practically only be able to visit Singapore once, since on subsequent visits (30/180 or more days from their first) they will no longer be considered "vaccinated" and will be subject to covid apartheid (this is even if they've had a booster). So the VTLs are not compatible with real opening up to the rest of the world.
2nd April update: