At a Glance
- Flu shot remains the best defense against seasonal flu, even after September.
- CDC reports 56% effectiveness for the 2024-2025 season.
- Experts say getting vaccinated yearly reduces severe illness and protects others.
- Why it matters: Getting vaccinated now lowers your risk of serious flu complications and helps curb community spread.
Seasonal flu continues to pose a health risk, but the most reliable protection is the annual flu vaccine. Health officials and experts emphasize that vaccination remains effective even after the traditional September-October window.
When to Get Your Flu Shot
The CDC states that the single best way to reduce the risk of seasonal flu is to get vaccinated each year.
CDC stated:
> “The single best way to reduce the risk of seasonal flu and its potentially serious complications is to get vaccinated each year.”
Infectious disease specialists Steven Gordon, MD, and Kaitlyn Rivard, PharmD, advise that the optimal time is September or October when new vaccines arrive, but the second best time is now.
Respiratory specialists Elena Diskin, Lisa Sollot, and director Christy Gray from the Virginia Department of Health confirm that the flu season runs from October to the end of April, with peak activity in January and February, so it’s still worthwhile to get a shot if you haven’t yet.
Elena Diskin, Lisa Sollot, and Christy Gray wrote in an email:
> “The season runs from October through the end of April,” they wrote, adding “we typically see the most flu activity in January and February.”
- Steven Gordon, MD, infectious disease specialist
- Kaitlyn Rivard, PharmD, infectious disease clinical pharmacist
- Elena Diskin, respiratory specialist
- Lisa Sollot, respiratory specialist
- Christy Gray, director of Immunization
Flu Vaccine Safety and Effectiveness
Flu vaccines cannot cause the flu. The CDC explains that needle-delivered shots use inactivated viruses or a single viral protein, while the nasal spray contains live attenuated viruses that are weakened so they do not cause illness.
CDC explained:
> “Flu vaccines cannot cause flu illness. Flu vaccines given with a needle (i.e., flu shots) are made with either inactivated (killed) viruses, or with only a single protein from an influenza virus. The nasal spray vaccine, which is for people between the ages of 2 and 49, contains live viruses that are attenuated (weakened) so that they will not cause illness.”
In the 2024-2025 season, flu vaccines were 56% effective, the highest in nearly 15 years, according to respiratory specialists Diskin, Solot, and Gray.
Diskin, Solot, and Gray said:
> “Vaccine effectiveness is measured by comparing the frequency of health outcomes (e.g., symptomatic illness, hospitalization, death) in vaccinated and unvaccinated people in the real world.”
Sai Paritala added:
> “In plain language, [vaccine effectiveness] describes how much less likely a vaccinated person is to get sick compared to an unvaccinated person, based on real-world data.”
| Vaccine Type | Composition | Can Cause Flu |
|---|---|---|
| Shot | Inactivated virus or single protein | No |
| Nasal spray | Live attenuated virus | No |
It takes up to two weeks after vaccination for full protection to develop, so exposure during that window can still lead to illness, but not from the vaccine itself.
Key Takeaways
- Get the flu shot yearly; September-October is ideal but still effective now.
- The 2024-2025 flu vaccine was 56% effective, the highest in nearly 15 years.
- Flu vaccines are safe and cannot cause flu illness.
With the season in full swing, getting vaccinated today offers the best chance to stay healthy and protect those around you.
