A no-deal Brexit would “likely” interrupt flu vaccine supplies, at the same time the UK is facing “a particularly virulent” strain of the illness, doctors have warned. Flu vaccines are offered free every year to those most at risk of the illness, including over-65s and pregnant women, and other people can pay a small fee for the jab.

The NHS says the best time to have a flu vaccine is in the autumn, from the beginning of October to the end of November. Last winter, 72% of eligible people over 65 and 45% of eligible pregnant women had the vaccine, according to Public Health England.

However, a number of doctors and other health professionals have expressed concerns that a no-deal Brexit would affect this year’s supply. The president of the Royal College of Physicians, Andrew Goddard, told BBC Newsnight: “I can’t sit here and say, ‘Don’t worry, no deal will be fine, no one is going to come to any harm, no one is going to run out of medicines.’

“What we can see is we’re likely to not have enough flu vaccine, we are likely not to have the flu vaccine coverage that we’ve had in previous years, and that is likely to have an impact on the NHS.”

Drugs manufacturer Sanofi UK said it would also expect issues with the vaccine in the event of no deal. Hugo Fry, the company’s managing director, told the BBC that more than 1 million doses of the vaccine would still need to be imported into the country after 31 October, due to a delay in identifying which strains of flu to put in this year’s supply.

He said: “In the world of vaccines, you get shortages more often than you do in medicines, for example, because of the complexity. Therefore imagine in a world where it is difficult to get things into a country and there’s a shortage of a particular vaccine, that’s when you want to rush it into the country in case there’s a shortfall.

“Rushing things into a country in a period post no-deal Brexit might be a bit difficult, for example. Unfortunately, I didn’t bring my crystal ball with me, but what we’re doing is planning for what we think will be the worst-case scenario.”

The deputy chief executive of NHS Providers, which represents NHS hospital and ambulance services, agreed that there could be problems, and thought doctors were “facing a triple whammy” this year regarding flu medicine. Saffron Cordery said: “We’re coming out of the summer, which has been a really tricky summer for the NHS. We are also facing a particularly virulent strain of flu coming from Australia.”

The Department of Health said: “We are working closely with vaccine suppliers to ensure they have robust contingencies in place. We want to reassure our patients that our plans should ensure that supplies of vaccines remain uninterrupted when we leave the EU on 31 October, whatever the circumstances.”