Ministers accused of overreacting to the Omicron variant will feel vindicated by the comments of Moderna chief executive Stéphane Bancel. In an interview with the FT, Bancel said he expects his company’s vaccine to suffer a ‘material drop’ in efficacy against Omicron – on the grounds that the new variant has 32 mutations to its spike protein. The protein, which the virus uses to attach itself to human cells, is targeted by the Moderna vaccine. The vaccine seemed to cope with previous variants – but they had fewer mutations. Bancel said the company’s scientists had told him: ‘This is not going to be good.’ Yes, it will be possible to re-design the vaccine to cope with Omicron, but it will take several months.

It marks a sharp change from a year ago, when Moderna emerged as the most effective vaccine, reducing symptomatic infection by 95 per cent. It was presented as a triumph for messenger RNA (mRNA) vaccines. This is still a novel technology, which involves programming human cells to produce the spike protein, rather than introducing the virus to the cells and letting them produce antibodies in response.

But the initial trials which stoked such optimism a year ago were based on just three months of data. They didn’t measure any drop-off in efficacy after that date, nor fading effectiveness against new variants. Initially, Moderna (along with Pfizer, which also works on the mRNA principle) was touted as a two-dose vaccine. But the outlook could be different if it turns out we need boosters indefinitely. Now, the government has slashed the gap between second doses and boosters from six to three months, which will place pressure on a booster programme already struggling to reach some vulnerable people.

Bancel’s interview sparked a reversal of yesterday’s rebound in global markets. If the Moderna vaccine were to struggle against Omicron, the same would probably be true of the other vaccines – as they all target the spike protein. Immunity gained through natural infection could be a little more effective, as it has been established in response to exposure to the whole virus rather than just the spike protein.

Balanced against all this is emerging evidence that Omicron might be causing less severe illness than its predecessors. Where (contested) data suggested a higher death rate from the Alpha and Delta strains than from earlier variants, there are some signs that Omicron might take us in the opposite direction. But Angelique Coetzee, chair of the South African Medical Association and the doctor who first reported Omicron’s existence, said the first people to be infected with the variant have shown mostly mild symptoms.

The dream ending to the pandemic would be a new strain which spread so rapidly that it quickly knocked out all other variants – but which didn’t make people severely ill. Omicron might not fulfil that job. But, if it does cause less severe illness, that might balance out against possibly higher transmissibility and a greater ability to evade vaccines.<//>