Why do we usually get colds or the flu in fall and winter? [WE EXPLAIN]

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Season for colds and flu is in the belt. We have already got used to the fact that the autumn weather brings with it runny nose, coughing and sneezing every year. But do we wonder why we catch infections more easily when it gets colder outside?

1. Colds are most often caused by coronaviruses and rhinoviruses, and the flu is caused by influenza A, B and C viruses
2. Influenza viruses become active at the beginning of October, and in our climate they are favored by coldness and low air humidity
3. Cold air slows the rate of nasal mucus removal with viruses and the activity of phagocytes
4. If you have any disturbing symptoms of an infection, such as difficulty in breathing, contact your doctor
5. You can find more such stories on the TvoiLokony home page

According to the US CDC, a disease control and prevention agency, “mostly because of colds, children miss school and adults miss work.” Although most fall / winter infections resolve on their own, flu kills around 290 to 650 people worldwide each year. people.

Let’s see what scientists say about the spread of viruses at low temperatures and how to prevent infection.

Cold versus flu

First, we have to distinguish between a cold and the flu. We associate colds with three main symptoms: sore throat, stuffy nose, and coughing and sneezing. Over 200 viruses cause them, but by far the most common culprits are coronaviruses and rhinoviruses.

Four coronaviruses are responsible for 10 to 30 percent. colds in adults. They belong to the same family as SARS-CoV-2, which causes COVID-19. However, these infections are most often mild. Interestingly, about a quarter of people infected with the virus that causes the common cold have no symptoms at all.

Flu develops as a result of infection with the flu virus. There are three types of influenza virus: A, B and C.

Cold and flu have many similar symptomsbut flu is known by a high fever, muscle aches, cold sweats or chills. As with the common cold, a significant number of people who are infected with the flu virus do not show any symptoms.

Now that we know the differences between the common cold and the flu, we can check when we are most susceptible to infection.

Zobacz: Do you want a flu shot? We explain how to do this

Infections are seasonal in nature

The CDC has long monitored the activity of influenza viruses. It can occur at any time of the year, but most cases follow a seasonal pattern.

The first signs of the activation of influenza viruses usually appear in October, with peak activity in the middle of winter. There are also periods when flu infections last until May.

What is different in areas with a tropical climate. Influenza in these regions increases during the rainy season or remains constant throughout the year.

Scientists do not fully understand how viruses are able to cause infections at both extremely low and high temperatures with such varied air humidity. There are several theories explaining this fact. They talk about how the cold affects how viruses behave, how our immune system deals with infections, and about being in crowded places or less exposure to sunlight.

See: Serious flu or common cold?

Cold air affects our first line of defense against the virus

Cold and flu viruses try to enter our body through the nose. However, this one has advanced defense mechanisms.

Our noses produce mucus. Viruses get trapped in this sticky and thick secretion that is constantly moved around thanks to tiny hairs called cilia that line our nasal passages. When we swallow mucus with pathogens, stomach acids neutralize them. Meanwhile, cold air cools the nasal passage, slowing down mucus clearance.

When the virus overcomes this defense mechanism, our immune system begins to fight the intruder. Phagocytes, or specialized immune cells, absorb and digest viruses. However, also in this case, cold air reduces their activity.

Rhinoviruses prefer cooler temperatures, which makes it difficult not to catch a cold in the fall or winter. Laboratory tests showed that these viruses died faster when body temperature rose.

The lack of vitamin D and the crowd are conducive to the flu

In winter, the level of UV radiation is much lower than in summer. This has a direct impact on the amount of vitamin D our body produces. There is also evidence that vitamin D contributes to the formation of an antimicrobial molecule that limits the ability of the influenza virus to replicate.

Therefore, some doctors recommend taking dietary supplements containing this vitamin in winter. In fact, a 2010 clinical study showed that school-age children who were given vitamin D3 daily had less influenza A.

Vitamin D has also been shown to provide protection against acute respiratory infection. However, no large-scale clinical trials have been conducted so far, and the discrepancies between individual studies make it difficult for scientists to summarize them unequivocally.

Another factor supporting fall and winter infections is staying indoors. Firstly, the piston promotes the formation of aerosols containing viruses, and secondly, the central heating dries the air. As we already know, air humidity is closely related to the incidence of flu.

Scientists continue to study the patterns of the spread of respiratory infections, trying to find other factors that affect our health. For now, we have several ways to protect.

How to prevent viral infections and treat their symptoms

As the temperature drops, the chance of catching a cold increases. The CDC estimates that adults get a cold two to three times a year.

It’s best to protect yourself:

1. washing your hands frequently with soap and water
2. without touching the eyes, nose or mouth
3. keeping a distance from the sick

And if we catch a cold, the CDC recommends staying at home with little contact. These rules also apply to the flu. However, in this case, vaccination is the best preventive measure. Experts at the CDC say: “Getting vaccinated against the flu in the 2020/21 season is more important than ever.”

In case of infection, we also have proven home remedies. They will help to relieve symptoms, e.g. crushed garlic, warm water with honey and lemon, aromatherapy or inhaling water vapor.

However, it is necessary to contact a doctor if you notice:

1. breathing difficulties
2. persistent chest pain or abdominal pain
3. severe pain or muscle weakness
4. seizures
5. difficulty urinating
6. fever or recurrent cough
7. persistent dizziness or confusion
8. worsening of an existing chronic disease

See also:

1. Onion syrup – a cold remedy not only for children
2. Influenza vaccines will be rationed. The Ministry of Health decided so
3. GPs do not work 24 hours a day. What to do when we need help in the evening or on a holiday?
4. 77,7 thous. suspicions and cases of influenza and 7,7 thous. coronavirus infections from early September

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