February 03, 2023
The viruses that cause influenza circulate all year long, but they are most widespread in the United States during late fall and winter. That’s why that time of year is referred to as flu season.
The exact timing of flu season varies from year to year. And since the onset of COVID-19, its timing and duration have been less predictable. In the U.S., it usually begins in October, reaches its peak between December and February, and ends sometime between March and May.
One reason why flu season occurs when it does is that flu viruses survive better in cool, dry weather. Another reason, which was discovered more recently, is that cold temperatures appear to significantly reduce the number of cells in the nose that fight viruses and bacteria. Spending more time with people indoors during colder weather also makes it easier for the virus to spread.
When you’re exposed to a virus, your immune system naturally develops antibodies to fight it. Flu vaccines help your body develop those antibodies without infecting you with the virus. Ideally, being vaccinated will prevent you from getting the flu at all. And if you do get sick, the symptoms are usually milder.
The ingredients that flu vaccines use to activate your immune system vary. Some vaccines contain dead (inactivated) flu viruses. Others contain flu viruses that are alive but weakened (attenuated). And still others contain antigens that have been grown in labs using recombinant technology (an antigen is the part of the flu virus that your immune system reacts to).
The Live Attenuated Influenza Vaccine (LAIV) is administered as a nasal spray.
Influenza causes between 12,000 and 52,000 deaths in the U.S. every year. For people with low immunity to the virus, even a less dangerous case can cause debilitating symptoms. Getting vaccinated greatly reduces your risk of severe illness.
Another reason you should get a flu shot every year is that flu viruses mutate so often that the antibodies you developed to fight off the dominant flu strain one year may be ineffective against the dominant strain the next year. To address that, researchers try to figure out which will be the most common flu strains each year and develop vaccines to fight them.
How well the researchers predict which flu strains will be most common helps determine how effective the vaccines developed for that season will be. Studies have shown that when the researchers are accurate, getting vaccinated can reduce your chance of getting the flu by as much as 60 percent.
Getting a flu shot ahead of, or early into, flu season is important. The longer you go without it, the longer you risk having a low level of antibodies when you encounter a flu virus. Once you do get vaccinated, it takes three to six weeks to develop enough antibodies to offer the maximum amount of protection.
Flu season happens, due largely to how people, their bodies, and flu viruses behave in cold, dry weather. Generally, the best way to avoid getting sick is to get vaccinated before flu season begins. Check with your doctor or pharmacist to determine which flu vaccine makes the most sense for you. The Health Care Law defines flu vaccines as an essential health benefit, so the shot will likely be covered for free through your health insurance plan.