H1N1 Virus

About H1N1 Virus

• H1N1 is an Influenza A virus subtype that causes an acute respiratory infection commonly known as swine flu.
• Family: It belongs to the Orthomyxoviridae family.
• Type: It belongs to Influenza A, one of the four influenza types: A, B, C and D.
• Genome: It has a single-stranded, negative-sense ribonucleic acid (RNA) genome.
• Naming: H1N1 refers to Hemagglutinin 1 (H1) and Neuraminidase 1 (N1), which are two surface proteins used to classify Influenza A virus subtypes.
• Symptoms: Common symptoms include fever, dry cough, sore throat, headache, muscle and joint pain, runny nose, chills, sweating and severe tiredness.
  • Some people may also experience vomiting or diarrhoea.
    
• Transmission: It mainly spreads through respiratory droplets released during coughing and sneezing.
  • Infection can also occur after touching contaminated surfaces and then touching the mouth or nose.
• Incubation Period: Symptoms generally appear about two days after infection, although the incubation period can range from one to four days.
• High-Risk Groups: Pregnant women, children below five years, adults aged 65 years and above, and people with chronic diseases or weakened immunity face a higher risk of severe illness.
• Prevention:
  • Precautions: Regular handwashing, proper disposal of tissues, covering the mouth and nose while coughing or sneezing, and avoiding unnecessary contact with infected people can reduce transmission.
  • Isolation: Isolation can help limit transmission, particularly during the infectious period.
• Treatment: Treatment is mainly symptomatic, and antibiotics do not work.
  • Oseltamivir is an antiviral that works when treatment starts early, while paracetamol can control fever. 
• Vaccination: Annual vaccination is recommended because circulating influenza strains change frequently and the vaccine is updated accordingly.
  • A quadrivalent vaccine is available, and in India it is sold as Influvac Tetra 2024/2025.
• Diagnostic Test: Laboratory testing of respiratory samples can confirm infection.
  • Reverse Transcription Polymerase Chain Reaction (RT-PCR) can detect influenza-specific RNA and generally has better sensitivity than rapid diagnostic tests.