The Health Secretary has insisted the diphtheria risk posed to the public is “very low” despite an expected rise in the number of infections being recorded among asylum seekers.
Steve Barclay said hundreds of migrants were vaccinated against the highly contagious disease before being moved out of the Manston processing centre in Kent to hotels around the country.
He stressed the situation is being monitored “closely”.
As of 10 November, the UK Health Security Agency (UKHSA) had identified 39 diphtheria cases among asylum seekers in England for this year.
The number is understood to have risen to about 50, with officials expected to confirm the figure later.
It comes as Home Secretary Suella Braverman faced criticism about overcrowding and outbreaks of disease at Manston, and the Home Office said a man held there may have died from a diphtheria infection.
The site was cleared last week with all migrants moved into hotels, but Channel crossings resumed on Monday as bad weather cleared.
The Ministry of Defence recorded 36 people arriving in one boat on Saturday, taking the provisional total for the year so far to 42,190.
Mr Barclay, during a visit to the Royal Marsden Hospital in London, said: “We vaccinated a range of people at Manston before they were moved, so that was part of the targeted action that UKHSA put in place.
“Clearly within the population as a whole it’s very low risk, because there’s very high uptake of vaccinations within the local population, but we’re monitoring it closely and that’s why so many people were vaccinated – 500 were vaccinated before they left Manston.”
Asked about the risk to the general public, he added: “The risk is very low, partly because there is very high uptake of vaccination within the British public in the first place.
“But also we had a targeted action of vaccinations at Manston and so 500 people were vaccinated before they actually left Manston, and it’s something that UKHSA are monitoring extremely closely.”
Some public health experts raised concerns about the spread of the disease as migrants were moved to hotels.
The infection affects the nose, throat and sometimes skin.
It can be fatal if not treated quickly, but the NHS says this is rare in the UK and can be treated with antibiotics and other medicines.
A man held at Manston died in hospital on 19 November after crossing the Channel seven days earlier, Government officials said.
Although initial tests came back negative, a follow-up PCR test indicated “diphtheria may be the cause of the illness”.
Dozens of asylum seekers who had contracted the disease were infected before they arrived in the UK, Transport Secretary Mark Harper said on Sunday.
Health officials believe the timings of testing and the onset of symptoms indicate all cases were caught abroad, but they have not been able to rule out transmission in migrant centres.
Asked if councils taking in migrants from Manston have been warned about the risks of the highly contagious disease, Downing Street said the Government is “working with local councils”.
The Prime Minister’s official spokesman told reporters: “We take the safety and welfare of people accommodated at these sites very seriously.
“We’re working closely with the UK Health Security Agency and other health professionals and indeed councils to make sure all medical guidance and the robust protocols are followed and that we have contingency plans.”
When asked the latest number of migrants at Manston, the spokesman did not know a figure but said the site was “significantly below capacity”.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know...