The number of Covid-19 vaccinations globally has surpassed the total number of confirmed cases, a landmark moment that underscores progress made in taming the pandemic despite mounting concern about the threat of new variants.

According to the Financial Times vaccine tracker, the total number of doses administered climbed to 105m late on Wednesday while the number of confirmed cases was 103.5m.

While vaccination rates are accelerating rapidly, the rise in cases of Covid-19 is slowing, although that is due to measures other than vaccines because they have not yet affected transmission in most places.

The figures are incomplete due to the fragmented nature of reporting — and the real number of infections is likely to be many times higher than the total verified by diagnostic tests.

But Michael Head, global health research fellow at Southampton university, said: “The fact that we have so many vaccines is a huge good news story which has been fed to us in bits and pieces. This moment brings it together, showing how fast we have moved and far we have come.”

Health experts attribute the slowing growth in infections to continued lockdowns and social distancing measures, with a possible contribution from immunity acquired from prior infection in some places. 

Paul Hunter, professor of medicine at the University of East Anglia, said new infection rates peaked globally in early January and were now back to the level of last October.

Israel is the only country where vaccines are already reducing transmission because inoculation has been rolled out more extensively and rapidly there than anywhere else in the world. “There is evidence from Israel that vaccination is beginning to reduce infection,” said Dr Head.

But vaccines will soon make a big difference to transmission, at least in wealthy countries where billions of doses will be available over the next few months following weeks of wrangling — particularly in the EU — over supplies.

Data released by Oxford university on Monday suggested that its vaccine developed with AstraZeneca would reduce transmission by 67 per cent. Experts expect other leading vaccines, such as those made by BioNTech/Pfizer, Moderna, Novavax and Johnson & Johnson, to have similar effects though hard data are not yet available.

Devi Sridhar, professor of global public health at the University of Edinburgh, said: “A year ago I couldn’t have imagined that we would have so many effective vaccines. This is a real testament to human ingenuity.”

Sean Marett, chief business officer of BioNTech, the pioneering Covid-19 vaccine manufacturer, said: “There will be sufficient doses in the second half of this year to vaccinate everyone in the industrialised world who wants to be vaccinated.”

However one threat to progress is the emergence of new variants of the virus which are appearing more frequently as cases increase. Some are more infectious — and less susceptible to neutralisation by the immune systems of people who have been vaccinated against or infected by older forms of virus.

Vaccine manufacturers say their existing products continue to work against all the mutations detected so far, though less effectively against some new ones such as the South African strain. They also insist vaccines can be tweaked quickly if necessary to respond to further mutations, raising the expensive prospect of annual or biennial jabs being required in future.

Scatter chart showing how advanced economies are ahead on covid vaccinations, even though many have suffered a higher death rate from the disease

It is unclear how long it will take to inoculate the whole world. Confirmed purchases of Covid-19 vaccines amount to 7.2bn doses and 5.3bn of them have been bought by high-income and upper-middle income countries, according to Duke University’s Global Health Innovation Centre. Most of these vaccines will need two jabs. 

The Wellcome Trust estimates that not until 2023 or 2024 will everyone who needs a vaccine be able to receive one. Others think it could be sooner than that if wealthy countries and organisations donate excess doses to poorer nations.

Another potential problem is vaccine hesitancy and in particular whether enough young adults, who know that their risks of needing intensive care or dying from Covid-19 are very low, will agree to be vaccinated.

Prof Sridhar said one way to convince young people to be vaccinated — and help achieve herd immunity in the community — would be to point out the significant risk of developing debilitating “long Covid” symptoms in patients who did not become seriously ill.

“Two million people worldwide have died in this pandemic,” she said. “I am optimistic that we can get to the end of this without another 2m deaths.”