More than 40 guests in a quarantined hotel in Tenerife have been allowed to leave but others have been told they must test negative for coronavirus or wait until next month to travel home.

Local health officials have confirmed 44 people have been allowed to leave the Costa Adeje Palace hotel in Tenerife and that dozens of others deemed low risk can leave soon. It is unclear whether any UK citizens are among them.

But the vast majority of the 168 British guests locked in the hotel remain stranded because travel companies are unwilling to fly them home.

Jet2 has told guests that they will not be flown home before 10 March unless they have tested negative for the virus.

Another travel company, TUI, has urged travellers to remain in the hotel. And EasyJet said it could only accept passengers from the hotel who had been isolated for 14 days.

A spokesperson for Jet2 said its responsibility to its “customers, our colleagues and the general public remains paramount”.

“We will not fly any customer who has stayed at the H10 Costa Adeje Palace during the quarantine, until this incubation period has passed or unless they have been explicitly tested for Covid-19 by a recognised authority and are confirmed as clear of the virus,” said the spokesperson. “We will continue to release more information as it becomes available.”

More than 700 were quarantined in the Tenerife hotel after at least four Italian guests were diagnosed with coronavirus.

On Thursday, the Canary Islands minister of health said a group of 130 low-risk guests – including about 50 British nationals – would be able to leave because they had arrived on Monday and had not come into contact with the four Italians who tested positive.

A man stands on a balcony of the H10 Costa Adeje Palace hotel in Tenerife. Photograph: Joan Mateu/AP

Elsewhere the first cases of coronavirus were confirmed in Northern Ireland and Wales, with a further two people diagnosed in the UK.

Northern Ireland’s chief medical officer, Dr Michael McBride, said the patient had travelled from northern Italy via Dublin.

He told a press conference on Thursday night: “We have been planning for the first positive case in Northern Ireland and have made clear that it was a question of when, not if.”

He added the virus had the potential to become a “global pandemic” but there were “robust infection control measures in place”.

On Thursday, health officials confirmed two cases of the virus in England in people who had contracted it in northern Italy and Tenerife. On Friday England’s chief medical officer, Prof Chris Whitty, said two more patients in England had tested positive for coronavirus, bringing the total number of cases in England to 17 and the UK to 19.

Experts in infectious diseases said the two cases identified in the UK early on Thursday were not a cause for concern and that the measures of isolating confirmed cases and tracing potential contacts was working so far.

Quick Guide What are coronavirus symptoms and should I go to a doctor? Show What is Covid-19? Covid-19 is caused by a member of the coronavirus family that has never been encountered before. Like other coronaviruses, it has come from animals. The World Health Organization (WHO) has declared it a pandemic. What are the symptoms this coronavirus causes? According to the WHO, the most common symptoms of Covid-19 are fever, tiredness and a dry cough. Some patients may also have a runny nose, sore throat, nasal congestion and aches and pains or diarrhoea. Some people report losing their sense of taste and/or smell. About 80% of people who get Covid-19 experience a mild case – about as serious as a regular cold – and recover without needing any special treatment. About one in six people, the WHO says, become seriously ill. The elderly and people with underlying medical problems like high blood pressure, heart problems or diabetes, or chronic respiratory conditions, are at a greater risk of serious illness from Covid-19. In the UK, the National health Service (NHS) has identified the specific symptoms to look for as experiencing either: a high temperature - you feel hot to touch on your chest or back

a new continuous cough - this means you’ve started coughing repeatedly As this is viral pneumonia, antibiotics are of no use. The antiviral drugs we have against flu will not work, and there is currently no vaccine. Recovery depends on the strength of the immune system. Should I go to the doctor if I have a cough? Medical advice varies around the world - with many countries imposing travel bans and lockdowns to try and prevent the spread of the virus. In many place people are being told to stay at home rather than visit a doctor of hospital in person. Check with your local authorities. In the UK, NHS advice is that anyone with symptoms should stay at home for at least 7 days. If you live with other people, they should stay at home for at least 14 days, to avoid spreading the infection outside the home.

Experts have warned that schools could be closed and major sporting events, concerts and other public gatherings could be cancelled in an effort to contain the spread of the virus.

Whitty said the country should prepare to face disruption to many normal activities “for quite a long period of time, probably more than two months” and to pay a heavy “social cost” for efforts to thwart the virus.

The NHS may have to cancel planned operations during the peak of a major outbreak to free up beds and staff for patients with coronavirus, he said, adding that the service would find it “quite tricky” to deal with a huge increase in the number of cases.

The World Health Organization also warned that the outbreak had reached a “decisive point” and had “pandemic potential”.

UK ministers are finalising the government’s plan to respond to the increasing threat posed by coronavirus, which is expected to be published next week. Matt Hancock, the health secretary, said: “There is a good chance that we can avoid a pandemic. That’s a potential outcome but not a definite outcome.”

Public Health England is due to launch a major public information campaign next week to educate people about how to minimise the risks of contracting or spreading the virus. Experts have repeatedly stressed that regular hand washing remains the single best way of reducing risk.