Influenza, commonly referred to as the flu, is a viral respiratory infection that affects millions of people annually. While most people recover from it in a week or two, the flu can turn into a more serious condition if left untreated. The simple and most effective way to protect yourself from influenza is to get the annual flu vaccination.
Now, here’s the real question: When is the best time to get a flu shot? Getting vaccinated too early could mean fading immunity when flu season peaks, while waiting too long could leave you vulnerable. In this guide, we will walk you through the insights of how vaccines work, when is the best time to get flu shots, the benefits of flu shots, and flu shot details according to age. Let’s dive in!
What is a Flu Shot?
A flu shot is a vaccination to protect against influenza viruses. This virus is expected to circulate in a fixed season. Because of the highly contagious virus, the vaccine composition is updated annually by the global health experts.
Thanks to the research and the Centers for Disease Control and Prevention (CDC), individuals are recommended the vaccines according to their age, health, and other medical conditions. There are multiple types of flu shots available today, including:
- Quadrivalent (QIV) and Trivalent (TIV): These vaccines protect against three or four strains of the influenza virus, with quadrivalent offering broader protection.
- High-Dose Flu Vaccines: Specifically designed for older adults (65 years and older) to provide a stronger immune response.
- Egg-Free Vaccines: A good option for people with egg allergies, available for ages 4 and up.
- Intradermal Vaccines: These are thinner needles used for people between 18 and 64 years old, delivering the vaccine into the skin rather than the muscle.
- Live Attenuated Influenza Vaccines (LAIVs): Also known as the nasal spray flu vaccine, this type contains weakened live viruses and is given as a mist in the nose.
How Does the Flu Vaccine Work?
The flu vaccine contains inactivated and harmless flu viruses. These components are injected into the body as a preview of the flu virus, prompting your immune system to develop protective antibodies. Once vaccinated, your body develops antibodies to protect against the flu. So, when you encounter the real influenza virus, your immune system recognizes it quickly and fights it off.
That’s why even if you do catch the flu after vaccination, it’s usually shorter, milder, and far less likely to lead to serious complications. It takes about two weeks after vaccination for your body to build full immunity, which is why it’s important to know the best time to get a flu shot.
When is the Best Time to Get Flu Shots?
According to the Centers for Disease Control and Prevention (CDC), the 2023-2024 flu season resulted in 470,000 flu-related hospitalizations and 28,000 deaths. Flu is easily spread, most commonly at the beginning of winter.
Experts recommend that it’s best to get the flu shot in September or October. In case of missing the September-October window, getting the vaccine later is still better than skipping it altogether. Early fall is the best time to get a flu shot because :
- It allows enough time for the body to develop full immunity before flu season peaks
- Immunity lasts for about 6-8 months, covering the flu shot season (fall through spring)
- Vaccinating too early (like July or August) may lead to waning protection in February or March, when flu activity is still high
Flu Shots for Different Age Groups
Depending on the different age groups and medical conditions, the timing of the flu shots may vary but generally a one yearly dose of an age appropriate influenza vaccine is appropriate with the following exceptions
- Children 6 months through 8 years of age who have never received seasonal influenza vaccine and Children 6 months through 8 years of age who have not previously received at least 2 doses of seasonal influenza vaccine administered at least 4 weeks apart, both categories will need 2 doses of influenza vaccines in the same season
- Children who are 6 months through 8 years of age who have previously received at least 2 doses of seasonal influenza vaccine administered at least 4 weeks apart and children 9 years of age and older will only need one dose of influenza vaccine per season.
Annual/Ongoing Vaccines
Children:
- Influenza: Starting at 6 months.
- COVID-19 Vaccine: Recommended at 6 months and throughout childhood, the frequency depends on age and the latest guidelines.
Adults :
For healthy adults, an annual flu vaccination and COVID-19 vaccine are strongly recommended. Common adult vaccines include Tdap (Tetanus, Diphtheria, Pertussis), MMR (Measles, Mumps, Rubella), Varicella, and Shingles (Zoster) vaccines.
Flu Shot for Seniors
Older adults (65+) face higher risks of flu complications such as pneumonia and hospitalization. Vaccine lists include influenza (flu), at least one dose of the current COVID-19 vaccine, and the RSV vaccine depending on their health status and the season. Pneumococcal vaccines are also recommended for this age group.
Pregnant Women
There are several vaccines your physician will suggest you receive depending on your health and pregnancy conditions. For pregnant women, the Centers for Disease Control and Prevention (CDC) recommends several vaccines to protect both the mother and the baby. The list includes:
- Tdap
- Flu (Influenza)
- Covid-19
- RSV
- Hepatitis-B
- Hepatitis-A
Common Questions About the Flu Shot
To clear out the extra queries, here are the answers to a few of the questions related to the flu shot:
Can you get the flu in the summer?
Rarely, but yes, as influenza viruses circulate at low levels year-round. Seasonal influenza vaccine programs target fall and winter when flu spreads most aggressively.
When are flu shots available?
Flu shot availability typically begins in August. Pharmacies, hospitals, and primary care providers start rolling out vaccines in late summer to ensure wide access. Scheduling a shot in September or October strikes the perfect balance between availability and effectiveness.
Does the flu shot make you sick?
No, the flu vaccine does not cause influenza. Some people may experience mild side effects like a sore arm, fatigue, or a low-grade fever, signs that your immune system is responding.
Who should not get a flu shot?
Infants younger than 6 months. People with severe allergic reactions to vaccine components. Those with certain health conditions should consult their doctor before vaccination.
How does the flu vaccine work?
The flu vaccine works by triggering antibody production in your immune system. The vaccine builds primary flu prevention defenses against flu viruses.
Can you still get the flu after a flu shot?
Yes, because the vaccine isn’t 100% effective. However, the effectiveness of the flu shot lies in lowering your risk of infection, and if you do get sick, it reduces severity and prevents dangerous complications.
Does insurance cover flu shots?
Most health insurance plans cover flu shots at no cost. Pharmacies and public health programs also often provide free or low-cost vaccination clinics.
Is it too late to get a flu shot in January?
Not at all. The flu season typically lasts until April or May, meaning that January vaccinations still offer meaningful protection. Early vs. late flu vaccination shows that later vaccination still significantly reduces illness risk.
Conclusion
The best time to get a flu shot is early fall, ideally September or October, to ensure immunity during the height of flu season. Still, if you miss that window, vaccination later in the season remains highly beneficial. Annual flu vaccination is a proven, powerful tool for safeguarding individual health and strengthening community immunity. By staying informed about flu shot availability, consulting your healthcare provider, and planning your shot wisely, you’ll be prepared for whatever the flu season brings.
FAQs
Q. What is the flu shot?
A: A vaccine designed to protect against influenza viruses expected to circulate each year.
Q. How long is a flu shot good for?
A: Typically, 6–8 months, covering the entire flu season.
Q. Where to get the flu vaccine?
A: Flu shots are available at pharmacies, primary care offices, urgent care centers, hospitals, and community health programs.
Q. Who should not get a flu shot?
A: Infants under 6 months, people with severe allergies to vaccine ingredients, or those with certain medical conditions should avoid it or consult a doctor first.