Moderna says COVID booster works against Omicron subvariants

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Moderna has reported top-line data suggesting that its COVID-19 booster vaccine candidate stimulates a strong immune response against the Omicron subvariants BA.4 and BA.5, which have driven an uptick in infection numbers in recent weeks.

The news came hard on the heels of Moderna's announcement that it will build a research and manufacturing facility in the UK to produce COVID and other mRNA jabs, and an additional order for  60 million doses that could be fulfilled using the new Omicron-targeted version, if authorised.

The new vaccine – called mRNA-1273.214 – is a bivalent shot, incorporating mRNA that codes for the spike protein of the original 'wild-type' SARS-CoV-2 strain and the Omicron variant that emerged last winter.

According to a Moderna statement, the booster stimulated a greater than five-fold increase in neutralising antibodies against Omicron BA.4 and BA.5 subvariants, regardless of whether the recipient had been previously infected with COVID-19, one month after dosing.

All the subjects in the study had received a primary course of two COVID-19 vaccine doses as well as a third booster shot.

The response against BA4 and BA.5 was three times weaker than for the original Omicron strain BA.1, but nevertheless should provide "lasting protection," said Moderna's chief medical officer Paul Burton. Subvariants BA.4 and BA.5 have identical sequences of the spike protein.

Earlier this month Moderna reported results from the 800-patient study which showed that it was more effective against Omicron than its original Spikevax shot.

The data is being submitted to regulators around the world in the hope of getting authorisation of mRNA-1273.214 in time for booster immunisation campaigns in the autumn.

"We…are preparing to supply our next generation bivalent booster starting in August, ahead of a potential rise in SARS-CoV-2 infections due to Omicron subvariants in the early fall," said Moderna's chief executive Stéphane Bancel.

The FDA is due to meet with expert advisors on 28 June to discuss booster shots ahead of the coming winter, including mRNA-1273.214 and updated versions of Pfizer/BioNTech's Comirnaty vaccine.

Infections with BA.4 and BA.5 have been rising in the US, where they account for around a third of all cases – as well as Europe and South Africa – and are expected to become quickly dominant as they are highly transmissible.

They are causing concern as some reports indicate they may cause pneumonia more readily than the BA.1 and BA.2 subvariants, which are less likely to travel down into the lower respiratory tract. Meanwhile, there is also some data suggesting re-infections are more likely with BA.4 and BA.5.

In the UK, experts have recommended that a single dose of COVID-19 vaccine is offered this autumn to vulnerable people, care home residents and staff, frontline healthcare workers, the over-65s and people aged 16 to 65 with clinical risk factors.

Deliberations are still ongoing however about the possibility of offering a fourth shot more widely to protect against a resurgence in coronavirus cases that could place further stress on the health services.