People in the UK are being advised to wear masks in crowded places and to isolate if they test positive for Covid, due to a rise in cases linked to two new strains of the virus.

The strains—XFG, dubbed Stratus, and NB.1.8.1, known as Nimbus—are fuelling a surge in infections, with cases doubling since August.

Professor Lawrence Young, a virologist at Warwick University, shared with the Daily Mail that it’s concerning to see the uptick in cases and hospitalizations so early in the autumn season.

He attributes this to children going back to school, cooler weather leading people to stay indoors more often—frequently in poorly ventilated areas—and a decline in immunity.

Experts note that the new variants, one of which is associated with a notably painful sore throat, don’t seem to be more dangerous than earlier strains or cause worse illness.

However, genetic changes to the virus means that infections may become more likely.

Yesterday, health officials initiated their winter vaccination campaign, encouraging millions to get their Covid and flu shots as hospitalizations begin to rise.

The UK Health Security Agency (UKHSA) reported an increase in positivity rates from 7.6% to 8.4% within a week, alongside a rise in hospital admissions from 2.0 to 2.73 per 100,000 people.

Although scientists are still assessing the two strains, they believe they have slightly different characteristics than have previously been identified.

‘The symptoms are mainly similar to previous Covid infections—headache, coughing, runny nose,’ explained Professor Young.

‘But infection with the new variants is associated with a hoarse voice or a “razor blade” sore throat’. 

Stratus has been identified in particular with persistent dry coughs, tiredness and a fever. 

Now experts are urging people to take sensible action to stay safe and protect others from virus that can still be deadly.

‘There are no specific rules other than people taking responsibility to ensure that the elderly and most clinically vulnerable are protected,’ Professor Young explained.

‘You should test to check that you are infected with the Covid virus and isolate until you are not infectious.’

Covid tests are no longer free on the NHS but can still be bought at pharmacies.

It’s no longer mandatory to isolate if you test positive but voluntary guidance recently published by the UKHSA urges people to do so. 

But he added: ‘Where this is not possible, it’s important to reduce mixing with people in confined spaces and wearing a facemask to reduce the spread of infection.’ 

While he doesn’t believe there should be mandatory rules on isolating and wearing masks, he said: ‘There should be more public health messaging about Covid.

‘It’s not like having a cold, and can result in both short-term disease and long-term effects.’

Professor Stephen Griffin, a virology expert at the University of Leeds added: ‘Anybody, regardless of how healthy they are can develop serious symptoms.

‘It doesn’t always mean that because you were fine last time, you’ll be fine this time. Things change. Our immunity changes. The virus changes.’

He continued: ‘The virus is still bad—there are dreadful tales about children developing long Covid.

‘We have this issue around presenteeism in this country, and it doesn’t help that, you know, things like school attendance.

‘I think it’s really misguided that kids who are still ill are basically being encouraged to go to school.

‘If you can isolate and you can stay home and stop it spreading to other people, then it’s definitely worth doing that.’

Similarly, he added: ‘We should be improving indoor air quality, and we should be wearing filtering masks when we need to.’

While it is no longer mandatory to wear one, Professor Griffin, who developed long Covid himself, says he wears one on a bus and other crowded places. 

‘I would wear a filtering FFP2 mask or FFP3 mask, if I was in an environment that was poorly ventilated and very busy, on a train for example, or a bus, or a crowded lecture theatre,’ he explained..

Long Covid has been linked to more than 200 symptoms from brain fog to heart inflammation which last longer than 12 weeks after infection.

Professor Young added: ‘It’s important to get your Covid booster vaccine if you are eligible for a free jab, and if concerned, consider getting a private jab.’

Over-75s, people with weakened immune systems and care home residents are eligible for the winter Covid booster, available on the NHS app, online, or at walk-in centres.

Pregnant women and children are also invited for vaccination, and toddlers can this year get a flu spray at community pharmacies.

Some high street chemists are offering private Covid jabs, costing up to £99 ($134).

Stratus was first detected in January in Southeast Asia. 

By June, the variant had spread to 38 countries, leading the World Health Organization to designate it as a ‘variant under monitoring’. 

Nimbus was detected around the same time in China and soon spread across the world to Europe and the US. 

According to the UKHSA, roughly 63 per cent of monitored cases in the UK over the last month were Stratus, while 25 per cent were Nimbus. 

The health agency advises anyone with symptoms to stay at home if possible and avoid contact with vulnerable people.

Those who must go out are urged to wear a face covering.

But in fresh advice issued last week, they added: ‘Current data does not indicate that these variants lead to more severe illness than other variants in circulation.

‘If you have symptoms of a respiratory infection, such as Covid, and you have a high temperature or do not feel well enough to go to work or carry out normal activities, you should avoid contact with vulnerable people and stay at home if possible.

‘For those of us who absolutely can’t stay at home, the Living with Covid guidance remains unchanged, and will reduce the chance of passing on your infection to others.’

In the UK, ministers have repeatedly said they won’t resort to imposing lockdowns unless a doomsday Covid variant appears.