How to Prevent the Flu: What’s Possible?

Between 9 million and 41 million Americans were infected with some strain of influenza (“the flu”) in the 2023–2024 flu season. Out of the more than 330 million people in the United States, these infections led to roughly 700,000 hospital stays and 51,000 deaths.

Getting a seasonal flu vaccine is the best way to protect yourself from the flu, and there are other health habits you can engage in to support your immune system year-round.

Can You Prevent the Flu After Exposure?

People infected with the flu usually notice symptoms within two days of exposure. However, the severity of the illness depends on the following factors:

• The strain of the influenza virus
• The strength of your immune system
• Whether you received a seasonal influenza vaccine

Once the virus enters your body, there is a chance that your immune system will destroy the virus and keep you from getting sick. It’s also possible to have an active influenza infection without symptoms.

Researchers are unclear whether the dose of a virus—or viral load—you are exposed to plays a role in how sick you might become with the flu.

Next Steps If You Feel Symptoms Coming On

Once you begin to experience symptoms, there’s nothing you can do to stop an influenza infection. However, if you take prescription antiviral medications designed to fight influenza A or B (the two most common strains) within the first two days after your symptoms start, you may be able to decrease the severity of your infection.

Antiviral medications approved to treat influenza in the United States include:

• Rapivab (peramivir)
• Relenza (zanamivir)
• Tamiful (oseltamivir phosphate)
• Xofluza (baloxavir marboxil)

These medications will not kill the flu virus but can weaken its effects. Treating influenza with antiviral medications to avoid severe illness and complications is especially important for high-risk individuals, such as those with:

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Current pregnancy
• Diabetes
• Heart failure
• Weakened immune system

How to Keep Symptoms From Getting Worse

Antiviral medications can help prevent your flu infection from becoming too severe. But if you’ve missed the treatment window (the first two days after symptom onset), there are other ways to manage your symptoms and support your immune system.

Over-the-counter medications for fever, cough, or congestion can help relieve symptoms. You also support your immune system to better fight the virus by:

• Getting enough sleep
• Eating a balanced diet
• Reducing stress

Year-Round Flu Prevention Reminders 

Lifestyle

Supporting a healthy immune system isn’t just something you should do when you are sick. Maintaining a healthy lifestyle year-round can help strengthen your immune system and prepare it to fight infections like the flu and other viruses. In addition to the immune-boosting measures above, prioritize the following to support your immune health:

• Avoiding alcohol and recreational drugs
• Getting regular exercise
• Maintaining a healthy weight
• Quitting smoking

Flu Vaccine

You should also ask your healthcare provider about necessary immunizations, including the seasonal flu vaccine.

Vaccinations for influenza are updated annually to target the most prevalent flu strains. You may also want to consider other vaccines that protect your overall health—especially if you fall into a high-risk category.

Understanding Flu Vaccine Protection

The flu is most prevalent between December and February most years, and seasonal vaccines are usually released in September or October. The Centers for Disease Control and Prevention (CDC) recommends people receive their vaccination by late October for the best protection throughout the flu season.

Seasonal flu vaccines can’t guarantee you won’t become infected with influenza, but they help. According to the CDC, seasonal flu vaccines have been between 30% and 42% effective in preventing illness, hospitalization, and death from the flu over the last few years. The vaccine is modified yearly to target the top three or four virus strains expected to dominate the flu season.

There is no exact way to predict which flu strains will be the strongest or most prevalent from year to year, but even if the vaccine doesn’t entirely prevent infection, it can help weaken its effects so you can recover faster.

How to Prevent or Limit Flu Contagiousness 

If you or someone you know has the flu, prevention and steps to limit transmission are key. Once exposed, a flu infection can take one to four days to take hold, and you are most contagious in the first three to four days after symptoms begin. However, the flu can be passed on up to a week after symptoms start.

You can help prevent the spread of flu by doing things like:

• Covering your cough or sneeze
• Disposing of dirty tissues or other contaminated items
• Staying home when you are sick
• Washing your hands often
• Wearing a mask when you are around others if you are sick

Summary

There is no cure for the flu; even vaccines can’t prevent all infections. However, getting regular vaccinations and engaging in healthy behaviors to support a healthy immune system can help you fight the virus and avoid severe illness and complications—especially if you have a weakened immune system.