If you get sick this winter, it's likely because of these viruses. Here's how to protect yourself

European countries have seen co-circulating winter viruses since the COVID-19 pandemic, with health systems facing a potential "triple threat" of illnesses, health agencies say.

"The health, social, and economic impact of winter viruses is huge," Antoine Flahault, director of the Institute of Global Health at the University of Geneva, told Euronews Health.

"The serious forms of these infections, even infrequent, given the size of these seasonal epidemics, contribute significantly to hospital saturation during epidemic peaks," he added.

According to the European Respiratory Virus Surveillance Summary (ERVISS), the number of people consulting doctors for respiratory illness "remains at expected levels for this time of year" in the European Union and European Economic Area with increases in viral activity in some countries.

But could there be multiple concurrent epidemics this year?

Rick Malley, a senior physician in medicine with the Division of Infectious Diseases at Boston Children’s Hospital in the US said it’s “a little early to know exactly what this year is going to look like,” but that the COVID-19 pandemic disrupted the usual patterns for respiratory illnesses such as flu and respiratory syncytial virus (RSV).

"While I don't think there's going to be like a triple epidemic going on, it's very possible that you're going to have RSV and then flu, and in the midst of those two, you will have a baseline that might bump up at some point of COVID".

Which winter viruses are circulating in EU countries?

Flu is a contagious respiratory illness caused by influenza viruses that causes symptoms such as fever or cough that can in some severe cases lead to death.

According to the World Health Organization (WHO), it causes seasonal epidemics mostly during winter in temperate climates, while in tropical areas, flu can cause more irregular outbreaks.

At the end of November, flu was circulating at low levels in EU and EEA countries, but the virus was also increasing in some countries, according to ERVISS data.

Another winter illness spreading in Europe is respiratory syncytial virus, or RSV, a common virus that causes cold-like symptoms but can be dangerous in infants or older adults.

In Europe this year, an RSV epidemic appears to have started in the EU and EEA, according to health authorities, with an increase in positive tests.

The European Centres for Disease Prevention and Control (ECDC) warned in its latest disease threat report that "all countries should be prepared for a continued increase in RSV activity during the coming weeks".

Young children are most affected by RSV, though older individuals are also at risk, the ECDC says.

Cases of COVID-19, on the other hand, have been decreasing this fall after a peak in July in EU countries. According to the ECDC, COVID-19 levels were lower than or similar to levels at this time of year in 2023.

"COVID is less affected by the seasons than other respiratory viruses because it circulates all year round in successive waves," Flahault said. "So the probability is high that one of them will coincide with the seasonal epidemic of influenza or bronchiolitis (RSV)".

Malley added that other respiratory viruses circulate such as parainfluenza, metapneumovirus, or adenoviruses, but that COVID-19, flu, and RSV get attention because "they can often be more severe than the other viruses and secondly, we have a combination of vaccines and treatments and antibodies against them".

Norovirus, which causes vomiting and diarrhoea, is another virus they can see a lot of in the winter and spring.

Why are there more respiratory illnesses in winter?

Flahault says the mode of transmission of these viruses in close, crowded, and poorly ventilated environments can explain why they circulate more in winter.

“We spend more time indoors, we open the windows less often,” he said, adding that less UV light outside, use of central heating, and more air pollution could also be factors.

Better microbiological indoor air quality and FFP2 mask wearing where there is poor air quality could also help to prevent “the circulation of all respiratory microbial agents” such as COVID-19, flu, RSV, chickenpox, measles, whooping cough, and tuberculosis, Flahault added.

How can you protect yourself from winter illnesses?

"Vaccination is among the most effective ways to safeguard the most vulnerable in our society from severe illness, hospitalisation, and death," said Piotr Kramarz, a chief scientist at ECDC in an e-mailed statement to Euronews Health.

"Since many countries are still far from achieving adequate protection for target groups, it is crucial to boost vaccination rates for seasonal influenza and COVID-19 as the winter season has already begun," Kramarz added.

The ECDC also recommends that people stay at home if they have respiratory illness symptoms, that they frequently wash their hands, and ventilate indoor spaces.

"The sad truth is that COVID just reminded us… of the importance of simple measures that might really reduce the risk of transmission to susceptible people or to vulnerable people," Malley at Boston Children’s Hospital, said.

"It goes without saying that good hand hygiene is very important," as well as prioritising outdoor activities when you’re sick and avoiding seeing vulnerable people.

WHO Europe also recommends wearing a mask in certain situations such as if you’re at risk of severe COVID-19, to protect others in poorly ventilated spaces or if you suspect you have COVID-19.