COVID-19 Vaccines

The Moderna and Pfizer-BioNTech vaccines consist of messenger RNA (mRNA) which carries instructions to tell your body to make the spike protein of the virus. This then stimulates your immune system to produce protective antibodies against the spike protein. The vaccine mRNA will naturally be broken down by the body after two days. It does not enter the nucleus of cells and hence does not interfere with the DNA of the vaccine recipient.

The Moderna and Pfizer vaccines have shown a 94 - 95% efficacy in preventing COVID-19. Both vaccination consist of two doses, with the second dose administered 21 days later for the Pfizer-BioNTech vaccine and 28 days later for the Moderna vaccine.

The vaccines continue to be effective for at least 2 months with no signs of waning protection. MOH will continue to monitor and review data on the duration of immunity.

The dosing regimen for the primary series vaccination is 21 days apart for the Pfizer-BioNTech / Comirnaty vaccine, and 28 days apart for the Moderna / Spikevax vaccine. Two doses of the Pfizer-BioNTech / Comirnaty and Moderna / Spikevax COVID-19 vaccines are required to be fully vaccinated. A booster dose is recommended to be taken from five months after you have been vaccinated with two doses of the Pfizer-BioNTech / Comirnaty or Moderna / Spikevax vaccines.

Source: www.vaccine.gov.sg/faq

The Health Sciences Authority (HSA) and Expert Committee on COVID-19 vaccination have assessed that the Moderna and Pfizer-BioNTech COVID-19 vaccines are safe and effective for the general adult population, including people with chronic medical conditions. They have been granted interim authorisation for their use in Singapore under the Pandemic Special Access Route (PSAR).

The mRNA-based COVID-19 vaccines are not recommended for children under the age of 5 years for Pfizer-BioNTech /  Comirnaty COVID-19 vaccine and children under the age of 18 years for Moderna / Spikevax COVID-19 vaccine until more efficacy and safety data become available for these subgroups.

Persons with a history of anaphylaxis to mRNA COVID-19 vaccine or its components SHOULD NOT receive the mRNA-based vaccine again. Anaphylaxis is a severe life-threatening reaction with two or more of the following three criteria:

a) Hives or face / eyelid / lip / throat swelling
b) Difficulty breathing
c) Dizziness

Patients with the following high-risk allergic reactions to a previous dose of mRNA COVID-19 vaccine or its components SHOULD NOT be administered the vaccine.

a) Hives or face / eyelid / lip / throat swelling with onset within four hours post-vaccination.
b) Painful swelling of the inner surfaces of the mouth and/or large blisters spontaneously occurring at any time after vaccination.

Persons with a history of allergic reactions (including anaphylaxis) to other vaccines CAN receive the mRNA-based vaccine, unless they have a confirmed allergy specific to PEG (a component of the mRNA vaccine). Persons who were diagnosed with myocarditis after a dose of mRNA COVID-19 vaccines SHOULD NOT receive the vaccine again.

Source: https://www.moh.gov.sg/covid-19/vaccination

The vaccine should be administered alone with a minimum interval of 14 days before or after any other vaccine. There is no available data on the safety or efficacy of the vaccine if given simultaneously with other vaccines.

Persons who have recovered from COVID-19 and were fully vaccinated before their infection are considered to have completed their primary series. Persons who have not completed their primary vaccination series before recovering from a COVID-19 infection, are recommended to receive a single dose of an mRNA vaccine.

If you are due for your vaccination based on the schedules recommended in the national vaccination programme (e.g. to receive a booster dose about 5 months after two doses of mRNA vaccines), you may receive your next vaccine dose 28 days after infection, although you are recommended to do so three months from the infection for better effectiveness.

Source: www.vaccine.gov.sg/faq

The current COVID-19 vaccines still offer a high level of protection against severe illness even with the Omicron variant.

Source: www.moh.gov.sg

No, routine testing by serology is not required after getting COVID-19 vaccination to determine effectiveness of vaccination. Vaccinated persons who subsequently develop acute respiratory infections (ARI) subsequently would still need to be undergo COVID-19 testing as per MOH instructions.

As the vaccines are incapable of causing COVID-19, they will not cause false positive PCR test results.