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Feb 21, 2023

Cold & Flu

Why We Get Sicker In The Winter

Symptoms of common illnesses such as the flu and the common cold can be uncomfortable in many different ways. Despite the fact that the majority of occurrences of the common cold and flu tend to go away on their own, the flu generally kills between 290,000 and 650,000 people annually.

In a scientific breakthrough study, scientists may have discovered why we get more respiratory illnesses in winter. It appears that the immunological reaction in your nose is harmed by the frigid air, but how so?

How might viruses get into my nose?

Breathing and direct contact with virus particles are the 2 main ways that viruses enter your nose.

But how is that impacted by the cold winter weather? Germs are present year-round. Well, your body's immune response is weakened by frigid air, particularly in your nose, one of the first places where respiratory viruses come into contact with humans and plays a significant role in your immune system, according to a study published in the Journal of Allergy and Clinical Immunology.

What occurs when viruses invade my nasal cavity?

When bacteria is found in your nose, numerous small fluid-filled sacs are released. These sacs, called "extracellular vesicles" (EVs), swiftly penetrate the mucus to encircle and eliminate the bacteria before they have an opportunity to infect your cells. Essentially, the EVs eliminate the bacterium or microorganisms before they start to infect you.

The EVs react the same way with viruses as they do with bacteria. EVs are formed as a result of the activity of common cold viruses, and they all respond by surrounding and eliminating the virus particles in your mucus. The particles in these vesicles, known as microRNA, destroy the viruses. The Evs can then efficiently get rid of the viruses before they could connect to the nasal cells and cause an infection.

How does the winter season affect my body's defense mechanisms?

This study published in the Journal of Allergy and Clinical Immunology also indicated that your immune response is greatly impaired by cooler temperatures, particularly during the winter.

Researchers subjected nasal tissues to temperatures of 39.9° F (4.4° C) and discovered that doing so resulted in an approximate 9° F (5° C) fall in tissue temperature, with significant immune system ramifications.

This decline can considerably lower your nose's natural immune response. As a result, the quantity of EV production was dropped by more than 40%, and their quality was seriously damaged.

Due to this diminished reaction, the virus may be better able to adhere to and invade your nasal cells. Thus, the virus can then multiply and spread infections. Since you lose half of your immunity as a result of the modest temperature drop, colder weather is associated with an increase in viral infections.

Flu vs Common Cold: Symptoms

It's not always easy to distinguish between colds and flu based just on symptoms because they are both very similar. The flu and the common cold are both infectious respiratory illnesses, but they are brought on by different viruses.

The common cold can be caused by a variety of viruses, including rhinoviruses, parainfluenza, and seasonal coronaviruses, but the flu is only casued on by influenza viruses.

While flu symptoms might develop suddenly, common cold symptoms can develop gradually. General symptoms that distinguish the difference between the two are listed in the table below.

Cold Flu
  • Low-grade fever (below 102°F)
  • Thick, dark mucus
  • Watery eyes
  • Cough
  • Runny and/or stuffy nose
  • Congestion
  • Sore throat
  • Sneezing
  • Body aches or chills
  • Fever (between 102-106°F)
  • Dizziness or headache
  • Nausea and/or vomiting
  • Dry cough
  • Runny nose that may be clear and watery
  • Extreme fatigue
  • Sore throat
  • Sneezing
  • Body aches or chills

Typically, cold symptoms continue for approximately 1 week. You are infectious during the first 3 days after developing cold symptoms. You should stay at home and get some rest as you can spread the cold to others.

On the other hand, symptoms of the flu appear fast. About 1–7 days after coming into contact with the virus, you may begin to feel ill. In most cases, symptoms start to show up in 2–3 days.

The flu is quite contagious. In a relatively short period of time, it can have an impact on a sizable number of people.

How can I avoid getting sick this winter?

You can practice certain routines to keep healthy during this winter and stop the spread of illnesses.

  • Avoid making direct contact with others, especially those who may appear to be sick or ill. If necessary, remain at home while you are unwell and avoid contact with others to prevent spreading your condition.
  • Avoid touching your mouth, nose, and/or eyes.
  • Wash your hands thoroughly and frequently.
  • Keep dirty hands away from your face.
  • Ensure that you've received a flu vaccination this year.
  • Adopt healthier lifestyles, such as receiving sufficient rest, engaging in regular exercise, drinking enough water, and eating healthy. Individuals with a healthy diet, regular exercise, and adequate sleep will have a stronger immune system.


  • Huang, D., Taha, M. S., Nocera, A. L., Workman, A. D., Amiji, M. M., & Bleier, B. S. (2022). Cold exposure impairs extracellular vesicle swarm–mediated nasal antiviral immunity. Journal of Allergy and Clinical Immunology.
  • Nocera, A. L., Mueller, S. K., Stephan, J. R., Hing, L., Seifert, P., Han, X., Lin, D. T., Amiji, M. M., Libermann, T., & Bleier, B. S. (2018). Exosome swarms eliminate airway pathogens and provide passive epithelial immunoprotection through nitric oxide. Journal of Allergy and Clinical Immunology, 143(4).

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