H1N1 Influenza Virus Outbreak

Update #1 Date- 26/08/2026

Occurrence Update

Delhi is witnessing a significant surge in Influenza A(H1N1) cases, with 2,446 cases reported in 2026 following 138 additional cases in the latest 24-hour reporting period. The broader Influenza-A tally has reached 3,177.

In response, the Delhi Government has strengthened preparedness across hospitals, directing facilities to maintain dedicated flu corners, adequate isolation beds, testing supplies, medicines and round-the-clock medical staff.

Larger hospitals have been asked to maintain at least 10 isolation beds, while other hospitals should maintain at least five.

The Delhi Medical Association has advised residents to wear masks in crowded settings, maintain respiratory hygiene, avoid crowded places where possible and seek medical advice rather than self-medicating.

Schools have also been advised to intensify preventive measures.

About H1N1 Influenza

H1N1 influenza is a subtype of Influenza A virus that causes respiratory illness in humans. The currently circulating human H1N1 virus is commonly known as A(H1N1)pdm09, which emerged during the 2009 influenza pandemic and subsequently became part of seasonal influenza circulation.

Although it is often called “swine flu,” the virus currently circulating among humans is primarily a human seasonal influenza virus.

Influenza A viruses are classified according to two major surface proteins, hemagglutinin (H) and neuraminidase (N); H1N1 contains the H1 and N1 proteins.

The virus contains segmented, single-stranded RNA and primarily infects the respiratory tract.

H1N1 can cause illness ranging from mild respiratory infection to severe pneumonia and other serious complications, particularly among high-risk individuals.

Transmission

H1N1 influenza spreads mainly from person to person through respiratory particles released when an infected person coughs, sneezes, talks or breathes.

People who are nearby may inhale these infectious particles and become infected.

Transmission can also occur when a person touches contaminated hands or surfaces and then touches their eyes, nose or mouth.

The incubation period is generally around 2 days, although it can range from approximately 1 to 4 days.

Symptoms

H1N1 infection commonly has a relatively sudden onset and can cause:

Fever
Cough
Sore throat
Runny or blocked nose
Headache
Muscle and body aches
Chills
Fatigue
General weakness

Some individuals, particularly children, may also experience nausea, vomiting or diarrhoea.

Diagnosis

Molecular tests such as RT-PCR are highly sensitive and can detect influenza viral RNA.

Rapid influenza diagnostic tests can provide results more quickly but generally have lower sensitivity than molecular tests.

Treatment

Treatment of H1N1 depends on the severity of illness and the individual’s risk of complications.

Antiviral medicines are particularly important for people who are hospitalized, have severe or progressively worsening illness, or are at increased risk of complications.

Antiviral treatment should ideally be started as soon as possible, preferably within 48 hours of symptom onset, although patients with severe disease, hospitalization or high risk of complications may still benefit when treatment begins later.

Oseltamivir is an important antiviral medicine used for treatment of influenza and should be taken according to medical advice.

Antibiotics do not treat H1N1 because it is caused by a virus. Antibiotics may only be required when a healthcare professional identifies a bacterial infection occurring along with influenza.

Prevention

H1N1 can be prevented by following appropriate preventive measures, including:

Annual influenza vaccination
Regular handwashing
Covering the mouth and nose while coughing or sneezing
Avoiding close contact with infected people
Wearing a mask in crowded or poorly ventilated places
Maintaining good ventilation
Avoiding touching the eyes, nose and mouth with unwashed hands

People with influenza-like symptoms should stay home, avoid spreading the infection to others, and seek medical care promptly if symptoms become severe.

Public Health Recommendations

Residents are advised to:

Practice regular hand hygiene.
Follow respiratory etiquette while coughing or sneezing.
Avoid close contact with people who are ill.
Stay home when experiencing influenza-like symptoms where possible.
Avoid unnecessary crowd exposure during periods of increased transmission.
Seek medical attention promptly if symptoms become severe or worsen.
People at higher risk of complications should follow medical advice regarding influenza vaccination and treatment.
Healthcare facilities should continue surveillance for influenza-like illness and severe acute respiratory infections.

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