In recent months, hospitals across Asia, including India, have seen a steady stream of patients suffering from prolonged coughs, sore throats, fevers, and fatigue. What’s alarming is that these viral infections are no longer confined to a single ‘flu season’, instead, they’re appearing all year round. Health experts are increasingly concerned that this persistent wave of illness signals a changing pattern in how respiratory viruses are circulating, influenced by climate change, urban lifestyles, and weakened immunity in the post-pandemic era.
The Scene in India
We spoke to Dr G. Nasiruddin, Consultant- Internal Medicine, Fortis Hospital, Cunningham Road, Bengaluru to understand the flu and influenza case graph of India. According to him, “India has witnessed a notable year-on-year rise in influenza-like illnesses (ILI) and respiratory infections since 2023. Data from the Integrated Disease Surveillance Programme (IDSP) shows higher-than-usual H1N1 and H3N2 cases in 2024, with an extended flu season continuing well into summer and early monsoon. Doctors across major metro cities like Delhi, Bengaluru, Mumbai, and Chennai, report that ‘viral fever’ has become an almost constant complaint, affecting both children and adults.”
According to a research published in PubMed Central, the surge in flu is partly due to waning natural immunity after prolonged mask use and reduced exposure during the pandemic years. Frequent viral mutations and fluctuating weather patterns have only added to the challenge, creating an environment where infections spread more easily and recovery takes longer.
Also Read: Covid-19 Vs Monsoon Flu: Experts Helps How to Differentiate Between The Two
| Year | Known Cases (H1N1 / Swine Flu / Seasonal Influenza) | Deaths |
| 2014 | ~ 937 confirmed H1N1 cases in India | ~218 deaths |
| 2015 | ~ 42,592 cases | ~2,990 deaths |
| 2016 | ~ 1,786 cases | ~265 deaths |
| 2017 | ~ 38,220 cases | ~2,186 deaths |
| 2023 | ~ 5,350 H1N1 cases by end October | ~101 deaths in those months |
| 2024 | ~ 20,414 infected (H1N1 / seasonal flu) by December | ~347 Deaths |
Note- There is very limited information for the years 2018-2022.
Understanding Influenza and Its Types
According to Dr Nasiruddin, “Influenza, or the flu, is a contagious respiratory infection caused by Influenza A, B, and C viruses. Influenza A and B are responsible for most seasonal outbreaks, with A being the more unpredictable due to its ability to mutate and form new subtypes. These mutations, known as “antigenic drifts,” make it harder for the immune system to recognize and fight off the virus, which is why annual vaccination is recommended.”
Symptoms typically include high fever, cough, body ache, sore throat, and fatigue, but newer strains are causing longer bouts of lingering cough and throat irritation, often mistaken for allergies or pollution-related illness.
Also Read: Delhi Battles H3N2 Surge: Top 7 Reasons Behind the Flu Outbreak Explained
New Variants in the Past Year
Over the past year, H3N2 and Influenza B/Victoria lineage have been dominant in India. Click here to read a case study on Haryana state regarding the ursurge of flu cases. Many doctors have also observed an overlap of viral infections with bacterial throat infections, leading to more complicated recovery phases. The co-circulation of multiple respiratory viruses, including RSV and adenovirus, has blurred the lines between “flu” and “seasonal cold,” keeping both pediatric and adult wards unusually busy.
Flu Precautions to Take
With unpredictable viral patterns, prevention from flu is key. Here are some precautions listed by Dr Nasiruddin that you must take to stay safe:
- Annual flu vaccination for children, the elderly, and individuals with chronic conditions.
- Staying well-hydrated, maintaining good sleep hygiene and eating a balanced diet rich in antioxidants.
- Avoiding crowded or poorly ventilated spaces during peak infection periods can help lower risk.
- Simple habits like washing hands frequently, masking in crowded indoor areas, and avoiding sudden temperature changes, especially moving from air-conditioned environments to heat and humidity are also effective safeguards.
Also Read: Always Getting Sick On Your Off Days? There Might Be A Reason Behind It
Flu and The Climate Connection
“Climate change is emerging as a silent contributor to this new flu dynamic. Rising average temperatures, longer humid periods, and erratic rainfall patterns are extending the survival and transmission window of respiratory viruses. Cities with high pollution levels are seeing worse outcomes, as particulate matter weakens lung defenses and makes individuals more vulnerable,” shares Dr Nasiruddin.
Final Word
Summing up, experts warn that these overlapping factors, urban air pollution, global warming, and altered immune behavior, may make year-round respiratory infections the new normal. The takeaway: staying proactive about flu vaccination, respiratory hygiene, and immune health is no longer seasonal advice, but a year-long necessity.
FAQ
What is Influenza?
Influenza, or the flu, is a contagious respiratory infection caused by Influenza A, B, and C viruses.What are the symptoms of influenza or flu?
Symptoms typically include high fever, cough, body ache, sore throat, and fatigue. Lingering cough and throat irritation are some of the newer symptoms that people are experiencing.How to prevent flu?
Getting vaccinated, drinking enough water, maintaining good hygiene, avoiding poorly ventilated spaces, wearing masks in crowded spaces are some of the precautions that must be taken.
How we keep this article up to date:
We work with experts and keep a close eye on the latest in health and wellness. Whenever there is a new research or helpful information, we update our articles with accurate and useful advice.
Current Version
Oct 22, 2025 18:18 IST
Published By : Chanchal Sengar