The Paradox of an 'Outbreak': Why India Will Keep Seeing Surges in H1N1 Cases

As H1N1 cases climb sharply across India this monsoon, doctors say it's an old virus behaving unpredictably again.

Why Is India seeing another bad H1N1 season?

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In June, a 41-year-old man from rural Karwar in Karnataka's Uttara Kannada district visited three separate hospitals over 11 days before he was diagnosed with Influenza A (caused by the H1N1 virus). But, by then, it was too late.

The man succumbed to the virus while undergoing treatment at a private hospital in Mangaluru. This case was an early marker of what has become one of India's most active H1N1—or swine flu—seasons since the big pandemic of 2009.

'Biggest Outbreak in Years'

Sneha, a mother of two primary school children—10-year-old Ayushi and 13-year-old Aarav—in Delhi’s Malviya Nagar, says she was getting her children ready for school on a Monday morning when her son complained of “feeling sick.”

"He said he was having chills all over and felt like his throat was a bit itchy. I thought he might just be making excuses to bunk school. And even if he wasn't, I thought it would just be a regular cold that would sort itself out."

Sneha

"A few hours later, I got a call from his school. They asked me to come pick him up during the lunch break because he was running a fever and wasn't feeling well at all," she tells The Quint.

A couple of days later, her 10-year-old daughter came down with the same symptoms. Sneha says she had been reading in the news about the H1N1 outbreak, and so she decided to get her children tested, which is when they were diagnosed.

Speaking to her kids and other parents, she soon found out that many of her children's classmates and friends were simultaneously ill.

"Not everyone gets tested, but when several children fall sick one after another shortly after being in close contact with each other, it’s an obvious connection to make," she says.

"My kids's school is still open, but parents have been told to not send their kids to school if they have any flu-like symptoms."

Sneha

The cases are not confined to children. Arpit, a 34-year-old marketing professional in Gurugram, says he got tested after having persistent fever for three days straight that "didn't feel like a regular flu".

"It completely knocked me out. I had really bad fatigue and body ache. I went to the hospital on day two when I started experiencing breathlessness. The doctor suggested that I should get an H1N1 test done since there's been a surge in cases, and my symptoms seemed to match it. That's how I got diagnosed," he tells The Quint.

While he had a slightly more severe bout, Arpit says several people in his workplace have been falling sick with similar symptoms in the last couple of weeks.

Delhi reported over 1,400 cases by mid-August—nearly six times higher than the same period last year ( 229 cases), according to the National Centre for Disease Control (NCDC). Nationally, over 9,000 cases and 178 deaths were reported by early July.

Maharashtra alone has recorded a 70 percent year-on-year rise in cases compared to last year, with 30 deaths, while Punjab, Kerala, and Gujarat report the highest fatality counts nationally.

Kerala recorded 7,421 total cases and 88 deaths by 17 August, with most fatalities occurring in people over 50.

While officials say no deaths have been confirmed by the government in the national capital so far, hospitals across Delhi-NCR report increased flu-like admissions this monsoon season.

Why are cases particularly high this time around? And is it a cause for concern? Experts say the answers may lie in both how the virus has evolved and how human behaviour has changed.

H1N1 Never Left

According to the US CDC (Centre for Disease Control and Prevention), symptoms of H1N1 flu, Influenza A, or swine flu are the same as seasonal flu, which typically include fever, chills, cough, sore throat, and body ache.

Seasonal spikes in cases are recorded every year. India follows an unusual, twice-yearly pattern rarely seen in temperate countries: one wave during the monsoon (June-October) and a smaller one in winter (December-February).

The virus itself has been around and infecting humans for decades, and has caused several fatal outbreaks in the past.

How far back? Interestingly, the 1918 global Influenza pandemic (Spanish flu) was caused by a subtype of the H1N1 Influenza A virus.

It landed in Bombay in June 1918 and went on to kill an estimated 12-18 million people in India—the highest death toll recorded in any single country, worsened by wartime food shortages and overcrowding.

The virus circulating today is not directly related to the 1918 strain. It emerged in 2009 from a mix of Influenza genes from North American and Eurasian pigs, birds and humans, and was first identified in Mexico.

India's first confirmed case was a 23-year-old traveller diagnosed in Hyderabad on 16 May 2009.

The H1N1 virus currently circulating in India belongs to the same overarching lineage as the original 2009 pandemic strain (A(H1N1)pdm09), but it has evolved through gradual, ongoing seasonal mutations rather than remaining entirely identical. Hence, the seasonal outbreaks and spiking cases despite the virus being endemic in India.

“With increasing exposure, viruses become less virulent and adapt to infect at lower levels and do that periodically. Mutations are part of the process. This is called becoming endemic to a population. Endemic means present all the time," renowned virologist Dr Shahid Jameel explains.

That is the paradox behind every "outbreak" headline: an endemic disease, by definition, never disappears completely. What changes from year to year is the height of its seasonal peak.

Why the Record High Cases This Year

No single, confirmed explanation accounts for 2026's sharper spike, and health officials have been careful not to overstate one.

Doctors point to several contributing factors, including humid monsoon weather, increased indoor crowding, schools reopening after the summer break, and more awareness and testing, which may be detecting more cases than in previous years.

"In the past, monsoon illnesses often got brushed aside as "just seasonal fever" until they turned serious. "That mindset is shifting," Dr Sunil Rana, Associate Director and Head- Internal Medicine (Unit III), Internal Medicine, Asian Hospital, tells The Quint.

He adds that the rise in number of reported cases likely has more to do with increased testing, rather than an actual increase in the total number of cases itself.

He says,

"More patients are walking in within a day or two of showing symptoms, asking to get tested rather than waiting to see if it passes on its own. That's a meaningful change."

Is the Current Outbreak a Cause for Concern?

Most healthy adults recover from H1N1 within a week. The elderly, children, pregnant people and people with comorbidities and underlying conditions like heart disease, diabetes, asthma, and weakened immunity are typically at risk of severe illness, which can even turn into life-threatening complications.

Although not all ICU-admitted patients have comorbidities, according to Dr Kirti Sabnis, an infectious disease specialist based in Delhi, "around 80 percent of (H1N1) patients getting admitted to the ICU have some or the other immunocompromising condition or lung problem like COPD [chronic obstructive pulmonary disease]."

The bottom line is that the virus is here to stay, and seasonal spikes are unlikely to end anytime soon. So, experts say, the best course of action is to focus on prevention and seek treatment at the earliest to minimise the risk of complications.

Infectious disease specialists also say that the bigger risk isn't the virus itself but the habit of dismissing it as "just a cold," which delays treatment past the 48-hour window in which antivirals work best.

"From a clinical standpoint, what matters most right now is not letting fever go unchecked. Dengue and swine flu can look similar in the early days, so testing is key rather than guessing or self-medicating. We are seeing good recovery rates because patients are reaching us in time," Dr Harpreet Kaur, Medical Superintendent, Head – Lab Services & Blood Centre Transfusion Medicine and Blood banking, Haematology, Cytopathology, Aakash Healthcare, tells The Quint.

While it is nowhere close to the pandemic conditions of 2009, the rising death tolls in Kerala and Maharashtra suggest this year's wave is not nothing either. Health authorities have said they are keeping an eye on the increasing number of cases and monitoring the virus.

The good news is that health officials have ruled out a dangerous mutation as the cause of the current surge. This means that while cases have increased, there has been no alarming rise in fatalities or significant change in symptoms.

Public health authorities describe the current situation as a manageable strain on hospitals rather than a crisis. Hospitals in Delhi continue to maintain dedicated flu wards and antiviral stockpiles, and expanded testing are in place across the worst-hit states.

H1N1 flu is similar to COVID in that they are both respiratory illnesses, have an overlap in symptoms, and spread in a similar way, so keeping up COVID-appropriate behaviour is your best bet at keeping swine flu at bay as well, according to the experts.

Speaking to The Quint during the 2022 outbreak in Maharashtra, Dr Laxman Jessani, consultant, infectious disease specialist, Apollo Hospitals, Navi Mumbai, had said, "We have to make sure that we get our population vaccinated, because the disease is easily preventable with vaccines."