Moderna says it will increase its global supply of Covid-19 vaccines to up to 3bn next year as the company expands its manufacturing capacity to tackle new and existing strains of the virus.

The investment to boost production comes as India grapples with a severe wave of coronavirus fuelled by a new variant of the virus that has pushed its health system to the brink of collapse.

Stéphane Bancel, chief executive of Moderna, told the Financial Times that he was awaiting data about the B.1.617 strain circulating in India but that it was highly concerning.

“When I see the hospitalisation rate and the death toll right now, I am deeply worried that this is a very bad variant . . . I’m very worried that it’s as bad, maybe even worse than the South African variant,” he said.

India’s coronavirus death toll pushed past 200,000 on Wednesday as the country recorded more than 360,000 new cases in one day.

Bancel said that tackling new variants would be of the utmost importance over the coming year and that governments were seeking mRNA-based vaccines over adenovirus-based vaccines, which are made by Oxford/AstraZeneca and Johnson & Johnson.

The adenovirus vaccines have proven less effective in trials compared with mRNA jabs — which are more than 90 per cent effective — while also being plagued by concerns that they cause rare but serious blood clots in some patients.

Bancel said that since vaccine efficacy reduces over time, “if you start at 60 per cent efficacy at your first dose, 6-9 months after you’re going to be well lower on efficacy . . . if you could have a 95 per cent efficacy vaccine, why would you get a 60 per cent efficacy vaccine?”

As the focus turns to tackling emerging coronavirus strains, BioNTech’s chief executive said on Wednesday that he was confident the vaccine he developed with Pfizer would work against the variant in India.

Bancel said Moderna had invested “billions of dollars” to increase manufacturing at its partner sites in Europe and in its own US sites and would increase vaccine production to up to 1bn this year and then 3bn next year, compared with the 700m and 1.4bn targets previously announced.

The Massachusetts-based company aims to have a surplus of stock so that it can react quickly to demand. “Right now we’re hand to mouth, something is done, it goes on the truck, it goes. Our stock is zero,” Bancel said, adding that Moderna had bought new machinery, raw materials and was hiring more workers.

Some of Moderna’s mRNA drug substance is manufactured at drugmaker Lonza’s site in Switzerland while Spanish company Rovi makes the ingredients and carries out fill and finish of vaccine vials in Madrid. Both plants’ output will double while the drug substance made in Moderna’s US facilities will increase by 50 per cent. Output is expected to increase later this year.

The production boost is in addition to Moderna’s previously agreed deals with US manufacturer Catalent and French drugmaker Sanofi. On Monday, Sanofi said it would help fill and finish up to 200m doses of Moderna’s jab from September, joining other pharmaceutical companies in helping rivals boost vaccine production. In March, US drugmaker Merck agreed to produce Johnson & Johnson’s single-shot jab.

Moderna also said that new data showed its mRNA jab could be stored in a refrigerator for three months, longer than the one month previously stated, making it easier for doctor’s offices and vaccination sites without freezers to store and administer the jab.

Bancel said that supply for 2022 would be better estimated once the dosage for boosters targeting variants and vaccines for children were known. Both were in trials and Bancel said he had “very strong confidence that 50mg will be enough” for the booster shots.

“Any variant of concern we will chase in the clinic,” he said. “We will not slow down until this thing is fully under control and we can go back to our normal lives.”

Moderna’s vaccine uses a 100mg dose while the BioNTech/Pfizer jab uses 30mg. BioNTech and Pfizer said last month that they would boost manufacturing capacity of their mRNA vaccine to 2.5bn doses by the end of 2021 after increasing capacity in Germany.