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Updated 4 Jun 2022

Enhanced Primary Series


Who needs three doses as part of their initial vaccination?

A:Persons with significantly impaired immune system require three doses instead of two as part of their initial vaccination (primary vaccination series). This includes persons with the following conditions:

a) Transplant patients on medications that suppress the immune system, including solid organ and allogenic stem cell transplants
b) Cancer patients on active treatment with chemotherapy or on other therapies that suppress the immune system
c) Haematological cancers
d) Treatments for non-cancer conditions that suppress the immune system
e) End-stage kidney disease

f) Advanced or untreated HIV
 [Updated 4 Jun] Immunocompromised persons are recommended to receive 3 doses of the mRNA or the Novavax vaccine as the primary vaccination series. When and how can I register for my third dose?

If you are significantly immunocompromised, it is recommended that you receive a third dose of the same mRNA or Nuvaxovid vaccine you had received for the first two doses, two months after your second dose.


Please consult your treating specialist who has the best understanding of your medical condition, before receiving your third dose. If you are eligible, you may thereafter receive the vaccination in a hospital or Specialist Outpatient Clinic of your treating specialist, if he/she is offering vaccinations. Alternatively, please obtain a referral form duly completed by your treating specialist, and walk into any Vaccination Centre for your third dose.


End-stage kidney disease patients will receive an SMS link to book their third dose, as part of the enhanced primary series. In the event that you do not receive an SMS, you should obtain a referral form from your treating specialist and walk-in to any of the Vaccination Centre.

Why are three doses required for immunocompromised persons?
Persons with moderate to severe immunocompromise have a blunted immune response to vaccination and may not develop a good protection with the standard two vaccine doses. There is evidence that persons with moderate to severe immunocompromise will benefit from a third dose of the vaccine as it helps them develop a more protective immune response.
 [Updated 4 Jun] What is the dose required for the third dose?
A:Persons with moderate to severe immunocompromise should receive a third dose of the same mRNA vaccine or Nuvaxovid vaccine, with the same dosage as the first two doses received.

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