The risk of the public getting diphtheria is "very low" despite an expected rise in the number of infections being recorded among asylum seekers, according to the Health Secretary.
Steve Barclay said hundreds of migrants were vaccinated against the highly contagious disease before being moved out of the centre and into hotels around the country.
In the UK uptake for the diphtheria vaccinations is high as it is included in the 6-in-1 doses given to babies at eight, 12 and 16 weeks of age, and then again at 3 years and four months in the 4-in-1 pre-school booster.
By November 10, the UK Health Security Agency had identified 39 diphtheria cases among asylum seekers in England this year so far, with that figure understood to have risen to about 50 today, with officials expected to confirm the figure soon.
The number is understood to have risen to about 50, with officials expected to confirm the figure later.
A man held at Manston died in hospital on November 19 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".
It comes as Home Secretary Suella Braverman faced criticism about overcrowding and outbreaks of disease at Manston.
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."
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".
What is Diphtheria?
Diphtheria is a highly contagious infection that affects the nose and throat, and sometimes the skin.
Diphtheria can be a serious illness and sometimes fatal, especially in children, if it’s not treated quickly. Vaccination can prevent it.
How diphtheria is spread
It's spread by coughs and sneezes, or through close contact with someone who is infected.
You can also get it by sharing items, such as cups, cutlery, clothing or bedding, with an infected person.
Symptoms of diphtheria
Symptoms usually start 2 to 5 days after becoming infected.
Symptoms of diphtheria include:
- a thick grey-white coating that may cover the back of your throat, nose and tongue
- a high temperature (fever)
- sore throat
- swollen glands in your neck
- difficulty breathing and swallowing
In countries with poor hygiene, infection of the skin (cutaneous diphtheria) is more common.
If it's cutaneous diphtheria, it can cause:
- pus-filled blisters on your legs, feet and hands
- large ulcers surrounded by red, sore-looking skin
Treatments for diphtheria
The main treatments are:
- antibiotics to kill the diphtheria bacteria
- medicines that stop the effects of the harmful substances produced by the bacteria
- thoroughly cleaning any infected wounds if you have diphtheria affecting your skin
Treatment usually lasts 2 to 3 weeks. Any skin ulcers usually heal within 2 to 3 months, but may leave a scar.
People who have been in close contact with someone who has diphtheria may also need to take antibiotics, or may be given a dose of the diphtheria vaccination.
