Pfizer CEO Albert Bourla said on Tuesday that he believes it is 'likely' that a strain of COVID-19 could emerge that is resistant to vaccines.

However, the pharmaceuticals boss claimed that the company would be able to develop a new shot to tackle a vaccine-resistant strain within 95 days of its emergence, Fox News reported.

'Every time that a variant appears in the world, our scientists are getting their hands around it,' Bourla said.

'And they are researching to see if this variant can escape the protection of our vaccine. We haven't identified any yet, but we believe that it is likely that one day, one of them will emerge.'

He added: 'We have built a process that within 95 days from the day that we identify a variant as a variant of concern, we will be able to have a vaccine tailor-made against this variant.'

In July, Rochelle Walensky – director of the Centers for Disease Control and Prevention – warned that the coronavirus could mutate and potentially evade vaccines soon.

So-called breakthrough infections among people who've had Pfizer's vaccine – as well as shots from Moderna and Johnson & Johnson have occurred – although they rarely result in serious illness.

However, a virologist at the University of Saskatchewan in Canada told The Telegraph that it was unlikely that the coronavirus could mutate into a vaccine-resistant strain.

'It would require so many mutations in the spike protein that this virus wouldn't 'work' anymore,' Angela Rasmussen said.

Other experts recently blasted a 'fear-mongering' article warning of a 'doomsday' COVID-19 variant which could be worse than Delta.

The doctors emphasized the effectiveness of the jab against the virus and noted that vaccine makers can quickly adjust formulas to make vaccines more effective against variants, Fox News reported.

Their comments come in response to an article in Newsweek Magazine which claimed that the Delta variant has 'shattered' optimism that vaccines would help the pandemic wind down.

The Newsweek Magazine article questioned: 'Is there a Doomsday variant out there that shrugs off vaccines, spreads like wildfire and leaves more of its victims much sicker than anything we've yet seen?'

'The odds are not high that we will see such a triple threat, but experts can't rule it out,' the article reads.

The Newsweek Magazine article appears to draw a number of conclusions, including that the pandemic will continue to get worse and may stick around 'forevermore' – while continuing to mutate.

'The next variant could be Delta on steroids,' warned Michael Osterholm, an epidemiologist.

Osterholm, who leads the Center for Infectious Disease Research and Policy at the University of Minnesota, added that – because of the Delta variant – 'the number of intensive-care beds needed could be higher than any time we've seen.'

He said that an analysis from his team shows that every American who has not been vaccinated or had the disease yet, about 100 million people, will likely get it in the coming months.