Health — diseases, immunity, vaccines & public health

Health questions in UPSC Prelims usually test a chain: biological cause, route of spread, immunity or vaccine logic, and the public-health response.

• Meaning of health: Health is not merely absence of disease; the exam treats it as physical, mental and social well-being, linked with nutrition, sanitation, behaviour, surveillance and access to care.
• Disease classification: A disease may be communicable, non-communicable, genetic, nutritional, occupational, environmental or iatrogenic. UPSC often mixes these labels: tuberculosis is communicable; diabetes is non-communicable; sickle-cell disease is genetic; fluorosis is environmental; scurvy is nutritional.
• Public-health lens: Public health protects populations, not only individual patients. It uses vaccination, safe water, vector control, legally justified quarantine, screening, health education, data reporting and risk communication.
• Constitutional basis: Health is not named as a separate Fundamental Right, but Article 21 has been interpreted to include health and emergency medical care. Article 47 directs the State to raise nutrition and public health. Seventh Schedule places public health and sanitation mainly in State List Entry 6, while port quarantine is Union List Entry 28, inter-State quarantine is Union List Entry 81 and prevention of inter-state spread of infectious disease is Concurrent List Entry 29.
• Important cases: Parmanand Katara v. Union of India, 1989 held that every doctor has a professional obligation to give emergency aid. Paschim Banga Khet Mazdoor Samity v. State of West Bengal, 1996 treated failure to provide timely emergency treatment as a violation of Article 21. Consumer Education and Research Centre v. Union of India, 1995 linked workers' health and medical care with Article 21.
• Policy frame: National Health Policy 2017 shifted emphasis to prevention, primary care, health systems, digital records and financial protection. Ayushman Bharat, launched in 2018, combined Health and Wellness Centres with PM-JAY for hospital-care protection.
• Prelims trap: Curative care treats illness after it appears; preventive public health reduces risk before cases rise. A vaccine, mosquito-control drive or tobacco tax is therefore a population intervention even when an individual benefit is visible.
• Current-affairs link: Science and technology questions increasingly connect biology with institutions: WHO alerts, ICMR guidelines, genomic surveillance, vaccine platforms, antimicrobial resistance, digital immunization records and disease-elimination targets.