The keys to identifying the flu
In winter, cases of flu skyrocket, so it is important to recognise its symptoms and learn to differentiate them from other viruses.
Winter is synonymous with parties and family gatherings, but also with colds, congestion and the typical glass of water with lemon and honey. During this time of year, flu vaccination campaigns skyrocket to prevent infection, especially among the most vulnerable groups.
Not all influenza viruses cause the same symptoms, nor do all bodies react to them in the same way. In many cases, some signs can be confused with a common cold or even COVID-19. That is why it is essential to know how to identify the flu and how to prevent infection during these months.
What is influenza and its types
Influenza is a highly contagious respiratory disease caused by influenza viruses. It mainly affects the nose, throat, bronchi and, occasionally, the lungs. According to a study conducted by the Instituto de Salud Carlos III, influenza caused approximately 33,000 hospitalisations and 1,800 deaths between September 2024 and May 2025.
There are three variants of influenza that affect humans:A, B and C. Type A can cause pandemics, while type B only causes seasonal epidemics. On the other hand, influenza C only causes mild infections and there is no evidence that it spreads massively.
How to identify flu versus a cold and COVID-19?
It is often difficult to distinguish between the flu, the common cold, and COVID-19. This is because they share many of the same symptoms. However, there are some signs that can help you tell them apart.
The symptoms of the common cold are usually milder and disappear after a few days of rest. This condition is accompanied by nasal secretions, coughing, congestion, and sore throat. It rarely causes fever or severe pain like the flu.
On the other hand, distinguishing influenza from COVID-19 can be more difficult. Both viruses are spread in similar ways and share symptoms. According to the National Insitute on Aging, COVID-19 causes a change or loss of taste or smell that does not usually occur with the flu. Even so, only a test can confirm which type of infection it is.
Flu symptoms
Symptoms of influenza viruses usually begin two days after infection. These are the five most common signs:
- Fever, although this does not always occur in all cases.
- Cough and sore throat.
- Runny nose or nasal congestion.
- Headache, muscle and joint pain.
- Fatigue.
In some cases, other symptoms such as chills, nausea, vomiting and diarrhoea may also occur.
How to avoid infection?
Cold weather, humidity and enclosed spaces are the ideal environment for virus transmission. To reduce the risk of infection during these months, it is important to:
- Cover your mouth and nose when coughing or sneezing.
- Use disposable tissues.
- Ventilate closed rooms.
- Wash your hands frequently.
- Get vaccinated if you are part of a vulnerable group.
In most cases, the flu does not usually cause serious complications. Rest, along with medication, is usually enough for symptoms to improve.
In mild cases, it is recommended to drink plenty of fluids, maintain good hygiene, and ventilate enclosed spaces. On the other hand, if symptoms worsen, you should see a healthcare professional as soon as possible.
