Moderna's Spikevax bivalent Covid-19 vaccine: How safe is it?

Moderna's Spikevax bivalent vaccine targets both the ancestral strain of Covid-19 and the Omicron variant. PHOTO: REUTERS

SINGAPORE - The Health Sciences Authority (HSA) on Wednesday granted interim authorisation for the use of Moderna's Spikevax bivalent Covid-19 vaccine. It is expected to arrive in Singapore by the end of September. The Straits Times explains what this means.

Q: What is a bivalent vaccine?

A: A bivalent vaccine targets more than one strain of a virus. In Moderna's Spikevax, the vaccine targets both the ancestral strain of Covid-19 and the Omicron variant. A multi-variant vaccine works by stimulating an immune response against more than one antigen. An antigen is a substance that induces an immune response in the body, and includes toxins, bacteria and viruses.

This is unlike most Covid-19 vaccines, which target only one variant of the virus

Q: Who can take the bivalent vaccine?

A: The bivalent vaccine has been authorised for use as a booster for people aged 18 and above who have already received their primary series vaccination.

HSA did not say when the new vaccine will be made available here.

Q: How safe is the bivalent vaccine?

A: The safety of the new bivalent vaccine is comparable with that of Moderna's original Covid-19 vaccine, with mostly mild to moderate side-effects such as pain at the injection site, as well as fatigue and muscle pain.

These reactions are expected as part of the body's natural response to build immunity against Covid-19 and usually resolve on their own within a few days.

HSA will continue to actively monitor the safety of the vaccine and require Moderna to submit data from its ongoing clinical study to ensure that the benefits of the vaccine continue to outweigh the risks.

Q: What other bivalent vaccines are there?

A: Pfizer-BioNTech also has one that targets the original Covid-19 virus and the Omicron variants. It has been approved in some countries such as Britain as a single-dose booster for individuals aged 12 years old and above.

Though it is not yet approved in Singapore, Health Minister Ong Ye Kung said on Tuesday that the Health Ministry is working to bring bivalent vaccines into Singapore.

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Q: Does this mean that current vaccines are no longer good?

A: No. Mr Ong said on Tuesday that they "remain highly protective against severe disease", including Omicron BA.5 infections.

Singaporeans should receive their vaccinations without delay and not wait for variant-specific vaccines, as Covid-19 is still spreading in the community, he stressed.

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