There are three serious viruses going round Britain – which one do you have?

At his GP practice in south-west London, Dr Ziad Tukmachi has become increasingly concerned by the sheer number of patients arriving with prolonged symptoms from various respiratory infections.

“We’re seeing a lot of patients unfortunately with long-lasting symptoms that we’ve not really seen before,” he says. “Coughs progressing for four to six weeks after a virus. They’re coming into the surgery after several weeks, saying they’re still feeling very unwell. It usually starts with a few days of cold-like symptoms that then disappear.”

While this hasn’t been reflected in hospital admission rates – according to the latest data from the UK Health Security Agency (UKHSA), people being sent to hospital for flu-related issues are still in the medium concern range, well below last year’s numbers – it is being picked up by GPs around the country.

Dr Hussain Al-Zubaidi, lifestyle and physical activity lead for the Royal College of GPs, is another who has noticed increasing numbers of patients who aren’t so unwell that they need to visit A&E but are still suffering from persistent and burdensome illness.

“A lot more people are requesting sick notes, which is for an illness stretching over seven calendar days,” says Dr Al-Zubaidi. “The requests have been very high. We’re definitely seeing people with more protracted symptoms than normal.”

So what is going on?

Paul Hunter, a professor of medicine at the University of East Anglia, explains that the UKHSA keeps track of viral prevalence through the Respiratory DataMart System, which collects the results of swab tests from laboratories around the UK.

He says that the data show that respiratory infections have been steadily rising since the summer in all age groups, but particularly among those aged between five and 14 who then may transmit these infections to other family members. This seems to be a consequence of relatively high rates of three main viruses – flu, the JN.1 variant of Covid and rhinovirus, which causes the common cold.

“Flu rates are particularly on the rise in recent weeks,” says Prof Hunter. “I think there’s a lot more pressure on the health service from flu at the moment than from Covid.”

How do you know which virus you have?

Prof Hunter says that people with a persistent rhinovirus infection are more likely to experience symptoms relating to the upper respiratory tract such as a runny nose or sore throat.

“Rhinoviruses by and large only infect the cells in the nose and sinuses so don’t damage the lungs,” he explains.

As a result, anyone coughing for weeks is far more likely to have either flu or Covid, both of which are almost impossible to tell apart without the help of a PCR test as the symptom profile is now so similar.

“There are [subtle] differences between influenza and Covid symptoms but the illness is not sufficiently distinctive to enable even someone like me who specialises in infection, to make a reliable diagnosis without a test,” says Prof Hunter.

How dangerous are these viruses and how long does infection last?

While rhinoviruses are less deadly, they can still cause problems for anyone with underlying lung problems such as chronic bronchitis from air pollution or heavy smoking. “Even the common cold can kill occasionally,” says Prof Hunter. “Most of the time, that’s much less common than it is with flu which can cause problems even in otherwise reasonably healthy people.”

One of the problems with both flu and Covid is that they attach to receptors on cells in the lower airways, making them more likely to cause viral pneumonia. Prof Hunter believes that flu is actually now more virulent in this regard than Covid.

But one of the biggest dangers, and something that may be contributing to the current burden of persistent illness, is co-infections where unwell individuals become infected with more than one virus or pathogen at a time. Studies have shown that people can be infected with both flu and Covid, while flu can enable severe bacterial co-infections due to the damage it inflicts on your lung tissue.

“Flu damages the cells in the respiratory tract that help you clear the bad bugs out of your lungs,” says Prof Hunter. “So sometimes you might get over your acute illness, and then a week or so later you develop this very severe pneumonia which kills people. A lot of deaths after the flu each year are not actually caused by flu.”

However, Dr Al-Zubaidi says that in most cases any of these viral infections should clear up within a week. He suspects that one of the reasons people are unwell for longer periods is due to the growing numbers of long-term health conditions in the population, along with the prevalence of obesity, which impacts on immunity.

“These infections aren’t getting more severe,” he says. “We are just more unwell with background conditions that reduce our ability to fight off these kinds of infections.”

How should you treat these infections?

Because these are viral infections, antibiotics are not effective and you shouldn’t expect them. Instead, Dr Tukmachi says that GPs will initially suggest lifestyle measures such as taking multivitamin or zinc supplements to try to boost the immune system. Other doctors, such as GP Dr Semiya Aziz, also recommend getting plenty of rest, avoiding caffeine as this can dehydrate you, and using a humidifier and keeping rooms well ventilated through opening doors and windows, to help relieve cough symptoms. “Avoid lying on your back, which can make coughing worse,” she says. “Lie on your side or sit upright instead.”

For patients who fail to get better, doctors will then check for so-called “red-flag symptoms” that might indicate pneumonia such as shortness of breath, temperatures that are rising up and down and not going away, and most seriously, coughing up blood.

“Investigations with chest X-rays can sometimes get involved, as well as further blood tests looking at inflammatory markers,” says Dr Tukmachi. “These steps are important in trying to ascertain why they’ve got the infection for so long.”

If a patient starts to become more seriously unwell, GPs will then refer them to hospital where they may be treated with antivirals such as molnupiravir or remdesivir in the case of Covid or oseltamivir (Tamiflu) and zanamivir (Relenza) for severe flu.

But Dr Tukmachi is keen to highlight that the majority of the infections he’s seeing are not especially dangerous. “There hasn’t been a huge increase in hospitalisations, particularly among fit and healthy people,” he says. “They’re getting affected for a longer duration than they used to. I’d probably say that the average patient is now saying they’ve been ill for three to four weeks, rather than a few days.”