Influenza (flu) is a viral respiratory infection that affects millions of people each year. As we head into flu season in the United States during the COVID-19 pandemic, it’s important to know what to expect and how to prevent it.
Every year, flu vaccines are developed to protect against the most commonly circulating strains. Receiving the seasonal flu vaccine is the best way to protect yourself against becoming ill with the flu.
But how does the vaccine work? How long does it last, and when’s the best time to get it? Here’s what you need to know.
Development of the seasonal flu vaccine actually begins many months ahead of flu season. The viruses used in the vaccine are based on extensive research and surveillance into which strains will be most common during the upcoming season.
Seasonal flu vaccines protect against two types of influenza viruses: influenza A and influenza B. They can also be either trivalent or quadrivalent.
The trivalent vaccine protects against three flu viruses: two influenza A viruses and an influenza B virus.
The quadrivalent vaccine protects against the same three viruses as the trivalent vaccine, but it also includes an additional influenza B virus.
Once you receive your flu shot, it takes 2 weeks for your body to develop antibodies that provide protection.
It’s important to remember that during this period, you’re still vulnerable to becoming ill with the flu.
During that time, you should be extra careful to:
- practice good hygiene
- avoid touching your nose or mouth whenever possible
- avoid crowds if flu is circulating in your community
These precautions are exponentially more important while COVID-19 is still a factor. You can develop the flu along with other respiratory infections, so protecting yourself and others is important.
Your body’s immunity to the flu decreases over time. This is true whether you’ve had a vaccination or a flu infection.
Additionally, influenza viruses are constantly changing. Because of this, a vaccine from the previous flu season may not protect you through an upcoming flu season.
Generally speaking, receiving the seasonal influenza vaccine should help to protect you for the duration of the current flu season.
You’ll need to receive a seasonal influenza vaccine every year in order to have the best protection against influenza viruses.
The flu vaccine is produced by a number of private manufacturers and typically begins to ship to healthcare providers in August. However, there’s some evidence that it may not be advantageous to receive your vaccine this early.
If you receive your vaccine later, don’t worry. Late vaccination can still provide adequate protection, as influenza can circulate within your community through March or even later.
The flu shot is made with an inactivated virus, which means you can’t develop the flu from the seasonal flu vaccine. But there are several side effects that you may experience after receiving it.
Side effects from the flu shot are typically mild and only last a few days.
Flu vaccine side effects can include:
- redness, swelling, or soreness at the injection site
- low-grade fever
- general aches and pains
Influenza viruses are constantly changing and evolving rapidly. Circulating influenza viruses can mutate from one season to the next.
Researchers need to select the specific influenza viruses to include in the vaccine many months before flu season begins. This means what’s in the vaccine may not always match what’s actually circulating during flu season. This can decrease the effectiveness of the seasonal flu vaccine.
Age can also play a role in vaccine efficacy because your immune system tends to become weaker as you age. The
The higher dose is aimed at providing a better immune response and therefore better protection within this age group.
It’s still possible to get the flu after being vaccinated, but research has shown that the illness may be less severe and that people who receive a flu shot may be less likely to be admitted to the hospital if they get the flu.
People over 6 months of age should receive the flu shot each year.
It’s particularly important for people who are at an increased risk for flu-related complications to be vaccinated.
- people over 50
- anyone with chronic medical conditions
- people with weakened immune systems
- children between 6 months and 5 years of age
- people 18 and under who receive aspirin therapy
- pregnant women and women up to 2 weeks after pregnancy
- people whose body mass index is 40 or higher
- American Indians or Alaska Natives
- healthcare workers
- anyone living or working in a nursing home or chronic care facility
- caregivers of any of the above
Children under 6 months of age shouldn’t receive the influenza vaccine. To protect these children from potential exposure to the virus, all family members or caregivers should be vaccinated.
This is called herd immunity and will help protect those who can’t receive the vaccine.
Additionally, if you’re currently sick with an acute illness, you may need to wait until you’re better to receive the vaccine.
Before you’re vaccinated, you should let your doctor know if you’ve had:
- a prior allergic reaction to the flu vaccine
- complications from vaccines
- Guillain-Barré syndrome
These factors may indicate that you should not get the flu shot. But check with your doctor to see what they recommend.
Many flu shots contain a small amount of egg protein. If you have a history of egg allergies, talk with your doctor about receiving the flu shot.
Influenza viruses cause seasonal epidemics of respiratory illness every year and this year is particularly dangerous due to the ongoing COVID-19 pandemic. While some people might experience mild illness, others (especially certain high-risk groups) may experience a more serious infection requiring hospitalization.
Getting your flu shot each year is the best way to decrease your chances of getting sick with the flu. Additionally, when more people receive the flu vaccine, the virus is less able to circulate in the community.
You should aim to receive your flu shot every fall before influenza virus activity begins to pick up within your area.
If you experience any symptoms of a cold or flu, it’s important to avoid contact with others and get tested for the flu and COVID-19.