Explained: How Covid-19 waves differ across the world and in India

While the US and UK are witnessing their fifth wave, India is seeing its third. But within the country, Delhi is in the midst of its fifth wave

The Centres for Disease Control and Prevention of the United States identifies three waves of the 1918 influenza pandemic. The first was in the spring of 1918, followed by an increase in infections in the fall and then a rise again in winter of 1919.

In 2009, some countries like the UK witnessed two waves of H1N1 influenza, whereas others like Thailand saw three. The Middle East Respiratory Syndrome (MERS) had three waves in Saudi Arabia until May 2015.

While India is battling the third wave of Covid-19, with incidence of infections rising, many countries worldwide are witnessing the fifth wave. South