The updated Covid booster from Moderna produces a stronger immune response to the Omicron variant than the firm’s original vaccine three months after being given, according to data from the US biotech.
The company said the findings indicate that the “superior” immune response triggered by the booster is durable and should provide “important protection” against Covid in the months leading up to the winter.
The Moderna vaccine and a similar “bivalent” shot from Pfizer are central to the NHS autumn booster programme, which is offering the jabs to all over 50s and others most at risk from Covid, including health and social care workers, in the hope of protecting tens of millions of people.
“Bivalent boosters offer the potential for optimal protection against Covid-19 and this new data further supports the NHS autumn booster vaccine strategy in the UK,” said Darius Hughes, Moderna’s UK general manager.
Moderna’s bivalent booster shot primes the immune system to defend against the original coronavirus strain that emerged in China in 2019 and the first Omicron variant, BA.1, which fuelled the UK’s vast wave of Covid infections last winter.
According to the firm, when given as a fourth booster shot, the bivalent vaccine produced higher levels of antibodies against BA.1 than their original vaccine, regardless of how many previous Covid infections the recipients had experienced. The higher antibody response held for at least three months, the data suggest.
Moderna issued the results in a press release on Wednesday, with full details due to be presented at the IDWeek conference in Washington DC on Thursday. Previous results from Moderna have shown that the bivalent booster is also more effective than their original shot at priming the immune system against later Omicron variants known as BA.4 and BA.5.
While the results appear encouraging, it is unclear how well the boosters will work against new variants of Omicron that may drive a fresh wave of infections in the months ahead. Most Omicron in the UK today is the BA.5 variant, but health officials are concerned about descendants of Omicron, such as BQ.1.1, BF.7 and BA.2.75.2, which are better able to evade immunity built up from vaccinations and previous Covid infections.
Prof Danny Altmann, an immunologist at Imperial College London, said boosters targeting the BA.1 Omicron variant appear to be holding up well against BA.5, but that more detail is needed to understand how long that protection will last.
“Even the BA.1 boosters are holding up in real life data on protection from BA.5 reinfections and severity much better perhaps than us purists had predicted. So BA.1 boosters clearly are highly beneficial. Now the devil is in the detail in terms of relative durability,” he said.