​What is a variant and how does it occur?

All viruses including COVID-19 evolve over time and may change its properties. Mutations of a virus are referred to as a “variant” of the original virus. Depending on where the changes are located in the virus genetic material, mutations may affect a virus properties such as transmission or severity.

How are variants classified?

The WHO (World Health Organisation) and US Centers for Disease Control and Prevention (CDC) classifies variants into three categories:

  • Variant of Interest (VOI)
    A variant with mutations that may help it evade antibodies or bind more tightly to human cells. They have not yet been shown to be more infectious.

  • Variant of Concern (VOC)
    A variant that appears to be more infectious or cause more severe disease than other circulating coronaviruses.

  • Variant of High Consequences (VOHC)
    A variant of high consequence with clear evidence that prevention measures or medical countermeasures (MCMs) have significantly reduced effectiveness compared to previous variants.

Major types of COVID-19 variants (as of May 2021)

Variants of Concern​ (VOC)

P.1 or B.

​501Y.V2 or B.1.351

202012/01 or B.1.17



Brazil and Japan

​South Africa

United Kingdom


​"Triple mutant" of three prominent mutations:

E484Q: Helps the virus evade antibodies

L452R: Enhances virus replication and latches on
more tightly to human cells

P681R: Makes the virus more infectious

Mutations near the tip of the spike protein:

N501Y: Helps the virus latch on more tightly to human cells

K417T: Similar to the K417N mutation, it may help the virus to latch on tighter

E484K: Helps the virus evade some kinds of antibodies

​Mutations near the tip of the spike protein:

N501Y: Helps the virus latch on more tightly to human cells

K417N: Helps virus bind more tightly to human cells

E484K: Helps the virus evade some kinds of antibodies

Mutations in the spike protein:

N501Y: Helps the virus latch on more tightly to human cells. But not likely to help virus evade current vaccines

P681H: May help infected cells create new spike proteins more efficiently

​Effect compared to original strain ​More transmissable than original strain in preliminary studies

Studies suggest that P1 is 1.7 to 2.4 times more transmissible than the previous strain

​Thought to be up to 50% increased transmission

Thought to be up to 50% increased transmission and potentially increased severity

Will the COVID-19 vaccine cover against all strains of COVID-19?

Ministry of Health (MOH) states that current evidence suggest that the Pfizer-BioNTech and Moderna vaccines continue to offer good protection against the various COVID-19 variants. MOH will continue to monitor the evolving situation and global studies of vaccine efficacy against various COVID-19 variants.

How to stay safe from COVID-19 variants?

Stopping the spread of the virus remains key. Steps that you (and your loved ones) can take to stay safe from COVID-19 include:

  • Frequent hand washing

  • Wear a well-filtered mask (at least 95 per cent bacterial filtration efficiency) 

  • Physical distancing

  • Avoid crowded places

  • See a doctor if you feel unwell and stay at home

  • Being vaccinated. Vaccination can prevent disease and minimise transmission. To protect yourself and your loved ones (including those who cannot be vaccinated due to medical reasons), you are strongly encouraged to go for vaccination.
    To learn more about COVID-19 vaccination, visit www.vaccine.gov.sg


Ref: K21

Check out other articles on vaccines:

COVID-19 Vaccine Myths Busted!

COVID-19 Vaccine: Is It Safe for Pregnancy, Breastfeeding or Starting a Family?

The Truth About Vaccines

Childhood Vaccinations: What You Need to Know

Why Seniors Need Vaccinations