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 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 are 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. It was introduced on the NHS for babies in 2015.

Private meningitis B vaccinations cost between £100 and £120 per 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.”

Two sites in Kent were 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.