Causes of COVID-19

COVID-19 has one cause - infection with the SARS-CoV-2 virus. What varies is how it reaches you and who gets severely ill. Both halves matter for prevention.

The virus and how it spreads

• Airborne spread: the dominant route - breathing in droplets and fine aerosols released by an infected person breathing, talking, coughing or singing. Risk concentrates INDOORS with poor ventilation
• Close contact: longer time near an infected person raises the dose - households are the commonest transmission setting
• Surfaces: possible but minor; hand hygiene still helps as general respiratory-virus defense
• Contagious window: people spread the virus from a day or two BEFORE symptoms through the first week of illness; asymptomatic spread happens

Variants - the moving target

The virus mutates steadily; new variants differ in how easily they spread and how well they dodge immunity. This is why infections recur despite past illness, and why updated boosters target recent strains. Variants have consistently been handled by the same toolkit: vaccination, ventilation, and early care for the vulnerable.

Who gets infected

Anyone - immunity from vaccines and past infections reduces severity more than it blocks infection. Repeated mild infections are common in healthy people.

Who gets SEVERELY ill - the list that matters

• Age over 60, steeply rising with each decade
• Diabetes, chronic heart, lung, kidney or liver disease
• Obesity (BMI over 30)
• Weakened immunity: cancer treatment, transplants, steroids, HIV uncontrolled
• Pregnancy (moderately higher risk of severe illness)
• Unvaccinated status - still the strongest modifiable predictor of severe outcomes

What does NOT cause it

5G, cold weather, non-veg food, and the rest of the WhatsApp list. The cause is a virus through the air - everything else is noise.

One-line summary

COVID spreads through indoor air from infected people; anyone can catch it, but severe illness concentrates in the elderly, the chronically ill, pregnant women and the unvaccinated - the groups protection is built around.