Written By Abigail Julias
To most people, the flu is just a seasonal illness that leaves you sick for a week during the winter season. It’s annoying, but not life-threatening enough to get vaccinated against. But the same can’t be said for everyone, and there’s always a small chance the flu lands you in the hospital. Getting vaccinated against the flu is the best way to protect yourself during the flu season, while simultaneously helping to protect others from the flu through herd immunity.
What is the flu?
The flu is a respiratory illness caused by the influenza virus. Symptoms start showing one to four days after exposure to the virus, causing a variety of symptoms such as a fever, chills, headaches, muscle pain or aches, a runny nose, and/or fatigue, depending on the strain. Most people recover within a week or two, but the flu can occasionally become dangerous enough to require hospitalization and may even lead to death in the worst cases.
A “flu season” typically runs between October and May in the Northern Hemisphere, and April to September in the Southern Hemisphere. According to the New York State Department of Health, there were 445,545 reported cases of influenza during the 2025-2026 season in New York, and 551,278 influenza cases during 2024-2025.
Why do you need a new vaccine every year?
After receiving a vaccine, your body produces antibodies that protect against the viruses in the vaccine. These antibodies decrease over time, which is why booster shots for other infections such as Tetanus are recommended every ten years. But influenza is a constantly and rapidly evolving virus, which means vaccines from past years quickly become ineffective as new variants are made. New flu vaccines are created every year to cover the variants most likely to spread in the coming flu season, so vaccinations should be annual to receive the best protection.
Getting the flu shot doesn’t only help you
Influenza spreads from person to person. Even if your case of the flu doesn’t end up being life-threatening, you could unwittingly spread it to someone more susceptible to the illness or spread it to someone who then spreads it to even more people, multiplying its growth.
By vaccinating yourself, your increased resistance to the flu may save others’ lives. Herd immunity is a form of protection against contagious diseases that occurs when enough of a population is immune to an illness through vaccination. When enough people are vaccinated, the flu is much less likely to spread far enough to reach people who are extra vulnerable, such as children or the elderly. Getting the vaccine every year helps ensure a herd immunity is created for the people who can’t get the vaccine, saving not only yourself but the people around you.
How well does the flu vaccine work?
Depending on the season and strains, the flu vaccine’s efficacy may vary. While not 100% effective in preventing you from catching the flu, vaccinations are known to weaken it, leading to a 40-60% reduction in flu-related doctor visits, according to the CDC.
When should you get the flu shot?
As the body typically takes two weeks to develop protection after receiving the vaccine, it’s recommended to get a flu shot in September or October, before the flu season starts. It’s not too late to get vaccinated after that period, however, as the flu season peaks in February, and can sometimes continue past May.
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