Government scientists have identified the type of meningitis behind a fatal outbreak in Kent as a strain that most people have not be vaccinated against.

Gayatri Amirthalingam, the deputy director of the immunisation and vaccine preventable diseases at the UK Health Security Agency (UKHSA), said tests showed it was strain B of the virus.

Speaking to BBC Radio 5 Live, she said: “We are able to say this morning that we have now identified from some of the testing that it seems to be the group B meningococcal strain that is causing outbreak in Kent.”

Amirthalingam confirmed this was a strain that most people were not vaccinated against. She said: “We have a meningococcal vaccine covering four different strains in teenagers. Usually it is given at the age of 13 or 14 years of age. It covers four main groups A, C, W and Y.”

Amirthalingam urged young people in Kent to take up the offer of antibiotics. Asked if it was safe for students to return home, she said: “If you are a university student and you’ve been offered antibiotics, or anyone else who’s been offered antibiotics, please take that immediately and it will be absolutely fine for you to return home. It’s an effective measure for protecting yourself, but also as to your loved ones, your family and your friends.”

People born before 2015 are not protected against meningitis B unless they have had the jab privately. The vaccine was introduced on the NHS for babies in 2015.

Private meningitis B vaccinations cost between £100 and £120 a dose in the UK, with a full two-dose course costing about £200-£240. Boots offers two doses for £220.

A year 13 pupil in Faversham, named only as Juliette at the request of her parents, and an unnamed student at the University of Kent have died in the outbreak, and others are being treated in hospital.

The UKHSA is advising anyone who visited Club Chemistry in Canterbury on 5, 6 or 7 March to come forward for preventive antibiotic treatment as a “precautionary measure”.

Amirthalingam also confirmed that the disease could be spread by sharing vapes, after a mother of one of those in hospital with the disease said she suspected her daughter caught it from a vape.

Amirthalingam said: “Meningococcal disease is be spread through a number of different routes. Vaping is just one. It is very much linked to close contact. There are plenty of other activities that can also promote the spread of this infection. Not specifically vaping.”

Eliza Gil, a clinical lecturer specialising in infectious disease at the London School of Hygiene & Tropical Medicine, said: “These students won’t have any immunity to meningitis B.”

She told 5 Live: “Currently students aren’t offered it because the risk has historically been low and also because the protection is imperfect and not very long lived. So it was felt on balance of risk, that it wouldn’t be of benefit to students to routinely offer men B vaccination.”

On vaping, Gil said: “Sharing anything that goes in your mouth is a potential risk factor for transmitting a mouth-living bacteria. So for definite I would be not recommending vape sharing in general from a hygiene point of view. But also in this context it seems an easy enough thing to stop doing, even if we’re not sure if it was causative in this case.”

Helen Whately, the Conservative MP for Faversham and Mid Kent, urged the government to consider a “catch-up” vaccination campaign for young people.

Speaking to Times Radio, Whately, a former health minister, said vaccinations against meningitis B had been given to babies since 2015, but those affected by the current outbreak “won’t have been vaccinated as babies in that way because they were born before that”.

She said: “One of the things the UKHSA will need to look at is if there is now a greater risk around this outbreak – and in future – should there be some kind of vaccination catch-up for that group.”

The UKHSA denied there had been a delay in the response to the outbreak.

Speaking to Radio 4’s Today programme Amirthalingam said: “I don’t believe there’s been any delay in terms of the public health response.

She added: “With these individuals, some of whom are extremely unwell in hospital, it can be difficult to try and ascertain detailed follow-up information, but that was done very rapidly over the weekend to be able to give that information out and identify the links within 24 hours.”

Prof Paul Hunter, an expert in infectious diseases at the University of East Anglia, said doctors could have been informed earlier of the outbreak.

He said: “It’s not just about informing the public. The symptoms of the disease can be very mild. If they [doctors] know that there is a problem with meningococcal disease in the area, then they’re more likely to take those early symptoms seriously.”

“The problem with meningococcal disease is that you can go from being relatively mild to on death’s door within a matter of a few hours. It is critically important that you make that information very clear very soon.”

He added: “When I used to do this work some years back, I think we would have gone public at the point that we informed local GPs that there was such a problem, which might well have been quicker.”

Two sites in Kent have been open for the public to collect antibiotics and a further two are planned to open on Tuesday morning.

Louise Jones-Roberts, the owner of Club Chemistry, told the Press Association that more than 2,000 people would have visited the venue over the three dates.