Seasonal influenza: Everything you need to know about the viral infection

"Unlike the common cold, flu symptoms appear suddenly and are often more severe," explains Dr Palleti Siva Karthik Reddy, internal medicine and consultant physician, Koshys Hospital, Bengaluru. "While a cold might make you feel under the weather, the flu can lead to complications such as pneumonia, bronchitis, and even heart problems."

Types of influenza viruses

According to the World Health Organization (WHO), influenza viruses are classified into four types:

1. Influenza A: The most severe type, responsible for global flu epidemics, including subtypes such as H1N1 and H3N2.

2. Influenza B: Causes seasonal flu outbreaks but is generally less aggressive than Influenza A.

3. Influenza C: A milder form of the flue that does not lead to widespread outbreaks.

4. Influenza D: Primarily affects cattle and does not infect humans.

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Symptoms of seasonal influenza

Flu symptoms may appear 1-4 days after exposure and can last up to two weeks.

"Common flu symptoms include fever or chills, persistent dry cough, body aches, severe fatigue, runny or stuffy nose, sore throat, headache and dizziness, and vomiting or diarrhea," explains Dr Tushar Tayal, consultant, internal medicine, CK Birla Hospital, Gurugram.

"More severe symptoms are difficulty breathing or chest pain, persistent fever above 103°F, confusion or dizziness, bluish lips or face, and worsening cough with green or bloody mucus," he adds.

People at higher risks, such as young children, elderly adults, pregnant women, and those with conditions like asthma or diabetes should seek immediate medical care if symptoms worsen.

What causes seasonal influenza?

Understanding the causes, symptoms, and prevention strategies. (Image: Freepik)

"Seasonal influenza is caused by constantly mutating influenza viruses, which is why flu vaccines are updated yearly," says Dr Reddy.

There are three modes of transmission: airborne transmission where there are respiratory droplets from infected individuals, direct contact that includes touching contaminated surfaces and then touching the mouth, nose or eyes, and crowded environments such as schools, offices, public transport and hospitals, which increase flu transmission risk.

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Treatment and prevention options

While most flu cases resolve within 7-10 days, treatment can help speed recovery and prevent complications.

"For high-risk individuals, antiviral drugs like Oseltamivir (Tamiflu), Zanamivir (Relenza) and Baloxavir (Xofluza) can reduce symptom severity and duration by 1-2 days, and prevent serious flu complications," says Dr Tayal, adding, "Supportive care such as rest, hydration, over-the-counter medications, cough suppressants and decongestants, and steam therapy and humidifiers, are also helpful."

The best way to prevent the flu is through annual vaccination and good hygiene practices. "The flu vaccine is updated yearly to match circulating strains, making it the most effective preventive measure," Dr Reddy advises. As for good hygiene, "wash hands frequently with soap for at least 20 seconds, use alcohol-based hand sanitisers, and avoid touching your face."

Strengthening the immune system is equally crucial. "Eat a balanced diet rich in vitamin C, vitamin D and zinc. Exercise regularly and get 7-9 hours of sleep every night. Manage stress, as high stress levels weaken immunity," Dr Tayal notes.

If you do contract the flu, early treatment with antivirals and supportive care can speed the recovery and reduce the risk of complications.

Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for specific health diagnosis.