Getting the flu once is miserable enough, but the possibility of catching it twice in a single season is a reality many Americans face as the country experiences its worst flu season in over 15 years.

At a Glance

• You can contract the flu multiple times in one season due to different circulating strains of influenza A and B
• Immunity developed after recovering from one strain doesn't protect against other strains
• The current 2024-2025 flu season is classified as "high severity" by the CDC with an estimated 19,000 deaths
• Prevention strategies include vaccination, good hygiene practices, and avoiding close contact with sick individuals
• High-risk groups include unvaccinated individuals, the elderly, young children, and those with weakened immune systems

Multiple Flu Strains Lead to Multiple Infections

The influenza virus comes in several different types and numerous subtypes, primarily categorized as influenza A and B. When you get sick with one strain of the flu, your body develops immunity to that specific strain but remains vulnerable to others. This explains why some people experience flu symptoms multiple times during the same season - they're actually catching different flu viruses each time. Influenza A tends to cause most flu cases and mutates quickly, making it harder to predict and prevent compared to influenza B.

The predominant strains currently circulating in the U.S. include flu A H1N1, flu A H3N2, and one influenza B strain. Each of these can cause similar symptoms but represents distinct viral infections. People often mistake their second bout of flu for a prolonged initial infection or another respiratory illness entirely, but testing can confirm whether it's truly a different flu strain causing the new symptoms.

This Season's Severe Flu Impact

The current flu season has reached alarming levels of severity. Over 33 million cases have been reported nationwide, making this the worst flu season in more than 15 years. The CDC has classified the 2024-2025 season as "high severity," with approximately 19,000 deaths attributed to flu complications so far. The situation is further complicated by concurrent surges of COVID-19, norovirus, and respiratory syncytial virus (RSV), creating what some health experts are calling a "quad-demic."

Those at highest risk for multiple flu infections include unvaccinated individuals, adults over 65, children under 5, pregnant women, and people with compromised immune systems or chronic health conditions. These groups should be particularly vigilant about prevention measures and seek medical attention promptly if flu symptoms develop, especially after a previous infection earlier in the season.

Prevention and Protection Strategies

The flu vaccine remains the most effective prevention strategy, even if you've already had the flu once this season. The current vaccines are designed to protect against multiple strains, including influenza A H1N1, influenza A H3N2, and an influenza B strain. It takes approximately two weeks after vaccination to develop full immunity, and while the vaccine isn't 100% effective at preventing all flu cases, it significantly reduces the risk of hospitalization, serious illness, and death.

Additional prevention strategies include practicing good hygiene such as frequent handwashing, covering coughs and sneezes, avoiding close contact with sick individuals, and considering mask-wearing in crowded indoor settings during peak flu season. For those who do contract the flu, treatment typically involves rest, fluids, and over-the-counter medications for symptom relief. High-risk patients may benefit from antiviral medications like Tamiflu, which work best when started within 48 hours of symptom onset.

When to Seek Medical Care

Distinguishing between flu and other respiratory illnesses can be challenging due to overlapping symptoms. The flu typically presents with a rapid onset of fever, muscle aches, headache, fatigue, and often a dry, non-productive cough. However, older adults and those with compromised immune systems might not develop the classic fever response, making diagnosis more difficult without testing.

Medical attention should be sought immediately for serious symptoms such as difficulty breathing, persistent chest pain, confusion, severe weakness, or worsening of chronic medical conditions. Children require emergency care if they develop blue-tinged skin, severe dehydration, or extreme irritability. Remember that flu activity can continue as late as May, so maintaining preventive measures throughout the season remains important, even as spring approaches.