The flu time or the flu season is an annually occurring time period characterized by epidemics or outbreaks of influenza or flu. It typically occurs during the cold months of winter.

Once the flu months have set in, it usually takes about three weeks for a minor flu epidemic to peak and another three weeks for it to subside significantly.

During a pandemic, the flu activity may peak more than once. What we mean by the “peak month” is the month when the maximum number of flu patients test positive for influenza or flu virus infection.

Influenza or flu is caused by infection with the flu viruses A, B, and C. The A flu virus is the most potent and responsible for epidemics and pandemics.  C is the least potent of the three. The subtypes of these viruses, especially the A virus, keep on mutating every year because of resistance developed due to exposure and vaccinations of the previous year. New drugs and vaccinations, therefore, have to be developed. You can, therefore, get the flu more than once due to new strains of the subtype of these viruses.

Flu or influenza is transmitted throughout the year but it is during the flu season (cold season) that the incidence of flu cases rises roughly ten-fold or more. That is the time flu is at its highest incidence with symptoms seen in a vast number of the population. The cold dark and dry winters increase the risk for the spread of flu in the population.

Time of the flu season months

In temperate climates, seasonal epidemics occur mainly during winter. Countries with this climate include the United States, Canada, all of Europe, Northern Africa, the Middle East, Japan, and New Zealand.

In tropical regions, influenza may occur throughout the year, causing outbreaks more irregularly. However, the flu season is more prominent during the rainy season. Tropical countries include Mexico, the middle-lying countries of Central and South America, middle-lying countries of Africa, the Caribbean, and Southeast Asia.

The time of flu season is the month in temperate countries when winter sets in and its duration lasts for all of the winter months. In other words, the flu season begins during the start of the cold and dry winter months and ends when the cold dry climate abates.

Therefore, the flu season time differs in the northern hemisphere and the southern hemisphere because the cold climate months in the northern hemisphere differ from those in the southern hemisphere.

  • In the Northern Hemisphere, flu season lasts from October through May and from April through September in the Southern Hemisphere. In tropical countries, the flu can be spread throughout the year but more so in the rainy season.
  • In the United States, the flu season starts in October and lasts up to May with its peak in January and more in February. It can, however, peak as early as October or sometimes as late May.
  • In England, the flu season starts in October and ends in April.
  • In Australia, which is in the southern hemisphere, the flu season is from May to October with its peak in August.
  • In the tropical countries, the flu season is typically seen during the rainy season. The tropical countries include those in the South and Central America, sections of South Asia, Southeast Asia, Africa (particularly West and Central Africa), the Caribbean, Southwest India and North America.

In all areas, the flu season follows a typical pattern as explained above. It begins in the months of fall and ends at the start of spring. Its onset is seen early on, especially among children in schools. The number of absentees goes up and this early sign indicates the arrival of the flu season. Hospitals, too, see an overwhelming rate of admissions.

Why the flu season occurs in winter?

Flu epidemics or outbreaks are seen during cold climates for the following reasons:

  • The infected droplets in the air from a person with flu are able to survive more during these cold, dark and low humidity conditions, thereby enhancing aerosol transmissions from infected persons.
  • People stay indoors more during the cold weather. This makes them more exposed to higher concentrations of airborne viruses that may have been introduced by an infected person.
  • Due to reduced sunlight in winter and therefore its reduced ultraviolet radiation, virus damage is reduced. The ultraviolet rays from the sun are known to kill microorganisms including viruses.
  • Due to reduced sunlight, Vitamin D synthesis reduces in the body, which reduces your immunity, making you more prone to catch the flu infection in winter.
  • Dry winter dries up the nasal passages, which further increases your susceptibility. It is also believed that darkness lowers your immunity, which further makes you more prone to catch the flu during the dark winter months.
  • Due to cold weather, the flu virus has a longer life on the surfaces on which it is parked, increasing the chances of infecting other people.
  • The flu virus has a protective butter-like coating that melts when the virus enters the respiratory tract of the person. In summer, the coating melts before the virus enters the respiratory tract of the person, thereby preventing the person from getting infected. In winter, the coating becomes hard thereby enabling the virus to live longer.

10 health tips for the flu season

During the flu season, you must follow certain health precautions that could well save you from falling prey to this illness. The following recommendations will help.

  1.  Take your flu vaccine every year before the start of the flu season. There are compelling reasons for that besides offering you significant immunity against the flu virus.

  2.  When you venture out of the house, always cover your nose and mouth with a disposable mask, especially in crowded places. Change it twice a day or at least once a day. This will prevent airborne flu viruses from entering your nose and mouth and infecting you.

  3. Wash your hands often with soap and water. Scrub with soap for a minimum of 20 seconds. This will get rid of any germs present on your hand. If soap is not available, use an alcohol-based sanitizer.

  4. Keep a safe distance from anyone having flu. A safe distance is about 6 feet. Have no direct contact with such persons such as shaking of hands.

  5. Be wary of touching commonly touched objects such as doorknobs, bank notes, and telephone instruments.

  6. Clean the commonly touched objects of your house with a sanitizer several times a day. Similarly, follow the routine at your immediate workplace.

  7. Do not touch your eyes, nose, and mouth with your hands. This is the way the flu virus can infect you if your hands are carrying the virus obtained from commonly touched objects. Advise everybody at your workplace to follow this routine.

  8. If you have any respiratory tract infection, such as a cold or cough, keep it under control. This is because flu is an infection of the respiratory tract and a pre-inflamed respiratory tract will be very susceptible to the flu virus.

  9. Always maintain a healthy lifestyle. Have a nourishing diet of vegetables and fruits, exercise well, and stay away from vices. It will help build your immunity against all types of infections.

  10. Always stay aware and educated. It could well save your Valentine’s Day, which falls on Tuesday, February 14, the month when the flu season is at its highest peak.

  11. Finally, if you catch the flu infection, follow the supportive flu care tips to prevent its spread.

Monitoring of Seasonal Flu

Flu is a nationally notifiable condition since 2004. In the United States, the Centers for Disease Control and Prevention (CDC), tracks flu activity throughout the year and produces weekly reports during the flu season months of October to May.

CDC collects information on flu activity throughout the year in the United States, compiles it, analyzes it, and produces reports called FluView and FluView Interactive. This offers an in-depth study of the data obtained, which is updated each week.

This surveillance is necessary to correctly select influenza vaccine components and detect newly mutated influenza A viruses that may signal the start of a pandemic. Flu monitoring provides the basis from which this information can be obtained.