Scientists hedging bets with mixed COVID vaccine for Omicron and Wuhan variants

The new-generation vaccine has in-built insurance against the evolving COVID virus.

The jab made by Moderna - and Pfizer isn't far behind with its own version - still triggers an immune response against the original Wuhan version of the virus. But it also adds protection against the Omicron family of variants that have become so dominant this year.

The so-called bivalent - or twin-target - vaccine is the first to be approved by the UK medical regulator.

Clinical trials have shown it is safe and generates a much higher antibody response to Omicron.

The existing vaccine is less effective against the variant - it still gives good protection against death and hospitalisation, but doesn't stop people from being infected, particularly a few months after having the jab.

Omicron is likely to remain dominant this autumn and winter, so it makes sense to update the jab to try and reduce the level of infections in the population.

But why keep adding genetic material from the original 2020 virus if it has virtually disappeared?

It's because health authorities are hedging their bets.

The pandemic has shown us that the virus is unpredictable. A new variant that more closely resembles the Wuhan strain could come out of the blue. And the original virus caused many more deaths.

Combining protection against multiple viruses is the tried-and-tested approach already used in the flu vaccine.

That jab contains elements from three or, more usually, four different strains of influenza in the hope that it will protect people in the coming months.

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Moderna's new COVID jab still needs to be approved by the Joint Committee on Vaccination and Immunisation. The experts on the Committee will decide whether the vaccine should replace the current Moderna booster.

Everyone over the age of 50, younger people with some medical conditions, and health and care workers are due to have a top-up shot this autumn.

It looks likely that they will get the updated jab.

Moderna has already agreed to supply the bivalent vaccine to EU countries this winter, if it gets the nod from European medical regulators.

The JCVI doesn't always align with its EU counterpart so it could choose to stick with the current vaccine.

Is this the one and only tweak to the vaccine?

You wouldn't bet on it.

The updated jab protects against a broader range of mutations in the virus. But COVID will keep evolving and could by chance come up with something new that outwits our immune systems.

Then it's back to the drawing board.