🦠 Viruses: What They Are, How They Infect, How Vaccines Beat Them
📝 Last reviewed: August 2026
What a virus is: a tiny package of genetic material (DNA or RNA) wrapped in a protein coat — sometimes with a lipid envelope. It has no metabolism of its own and cannot reproduce without hijacking a living cell.
How infection works: the virus binds to receptors on a host cell, slips inside, and forces the cell's machinery to build thousands of new virus copies, which then infect more cells. That is why viral infections spread fast once they take hold.
Common viral illnesses: the common cold (rhinoviruses, coronaviruses), influenza, chickenpox, measles, hepatitis B/C, HIV, dengue, and COVID-19.
How antivirals and vaccines work: vaccines train your immune system with a harmless version of the virus (or a piece of it) so it is ready before the real one arrives. Antivirals block specific steps of the viral life cycle — entry, copying, or release.
Key facts: antibiotics do NOT work on viruses. Most viral infections are self-limiting — rest, fluids and fever control while your immune system clears them. Antivirals matter for flu, HIV, herpes and COVID in high-risk people.
Prevention: hand hygiene, cough etiquette, vaccination, and ventilation are the practical pillars — same advice that beat smallpox and nearly beat polio.
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