New Delhi: H1N1 influenza cases are rising across the national capital, with 1,777 cases of the H1N1 subtype reported so far in 2026, according to the latest reported figures. Delhi has also recorded a cumulative 2,602 cases of seasonal influenza, including Influenza A and B, with H1N1 emerging as the predominant subtype.

Doctors in Delhi-NCR are reportedly observing an increase in cases, with many families reporting that one infected member is followed by others developing symptoms. This rapid household transmission is often described as a “domino effect”, as prolonged close contact can allow the virus to spread from one person to another.

The infection can cause fever, chills, cough, runny nose, sore throat, headache, body ache and fatigue. Symptoms generally develop within one to four days after exposure.

Why H1N1 can spread quickly at home

H1N1, commonly known as swine flu, is a contagious respiratory illness that can spread more easily among people living in the same household.

Family members often share rooms, spend long periods indoors and come into close contact with one another. These factors can increase the chances of transmission when one person becomes infected.

The risk may be higher in poorly ventilated spaces, where respiratory particles can accumulate. Shared household items and frequent contact with common surfaces may also contribute to the spread.

Respiratory droplets and close contact

When an infected person coughs, sneezes or talks, they can release respiratory particles that may carry the virus.

People in close proximity may be exposed, particularly during prolonged face-to-face contact. The risk can increase when family members share enclosed spaces for long periods.

Reducing close contact with a person who has flu-like symptoms can therefore help limit household transmission.

Poor ventilation can increase risk

Tiny respiratory particles can remain in the air, especially in enclosed and poorly ventilated spaces.

Improving ventilation by opening windows and allowing fresh air to circulate, where practical and safe, can help reduce the concentration of respiratory particles indoors.

Family members should avoid gathering in crowded, poorly ventilated rooms when someone in the household is unwell.

Shared surfaces may contribute to transmission

Frequently touched surfaces such as door handles, light switches, remote controls, taps and refrigerator handles can become contaminated.

Although respiratory transmission is considered an important route for influenza spread, maintaining good hand hygiene and regularly cleaning frequently touched surfaces can further reduce the risk of infection.

Family members should avoid touching their eyes, nose and mouth with unwashed hands.

Isolating the sick person can help

A person with flu-like symptoms should, where possible, limit close contact with other household members, particularly those at higher risk of complications.

Providing a separate room may be useful when practical. Contact should be minimised, while ensuring that the sick person continues to receive necessary care, food and fluids.

Extra precautions are especially important around elderly people, young children, pregnant women and individuals with underlying health conditions.

Personal utensils need not necessarily be treated as a special source of infection if they are properly washed with soap and water. However, regular cleaning and avoiding unnecessary sharing while a person is acutely ill can be sensible precautions.

Masks and hand hygiene remain important

A symptomatic person can wear a well-fitting mask when they need to be around others, while caregivers may also use appropriate masks during close contact.

Frequent handwashing with soap and water is one of the simplest measures to reduce the spread of respiratory infections. Alcohol-based hand sanitiser can be used when soap and water are not readily available.

People should cover coughs and sneezes with a tissue or their elbow and dispose of used tissues appropriately.

Watch for symptoms and seek medical advice when needed

Common symptoms of H1N1 include:

  • Fever and chills
  • Cough
  • Runny or blocked nose
  • Sore throat
  • Headache
  • Body aches
  • Fatigue

Symptoms can appear rapidly after exposure. Most otherwise healthy people recover, but influenza can become more serious for vulnerable groups.

People who develop severe or worsening symptoms, including difficulty breathing, persistent chest pain, confusion or signs of severe dehydration, should seek urgent medical care.

With H1N1 cases being reported in significant numbers, early precautions within households can help reduce the risk of multiple family members falling ill. Staying home when unwell, limiting close contact, improving ventilation, practising hand hygiene and following medical advice remain important steps in controlling the spread.