The Omicron variant is galloping across the U.S. and many countries in Europe at a pace never seen since the pandemic began. If the United States set a new record of fresh cases on a single day on December 27 with over 0.54 million cases, the seven-day average is at 2,40,400 cases a day, a 60% increase compared to the previous week. At least seven countries in Europe — Britain, Denmark, France, Greece, Italy, Portugal and Spain — are witnessing a similar trend this week. While Omicron has emerged as the dominant variant in a few countries, it has not completely displaced the Delta variant. The twin threats from the two variants are responsible for fresh cases reaching record numbers in many countries. The Omicron variant has a superior ability to cause breakthrough infections in fully vaccinated people and also cause reinfections in people who have been previously infected. Early data from South Africa and the United Kingdom suggest a reduced risk of severe disease requiring hospitalisation particularly among those fully vaccinated and previously infected. But it is still too early to draw conclusions as there is an inevitable lag between infection and hospitalisation, and the protection offered by vaccines against Omicron in older and other vulnerable populations is still not clear. India has been witnessing a surge in cases in many States. The total number of Omicron variant cases reported in India is inching closer to 1,300 and has already been reported from 22 States. There is no reason to believe that the variant will behave differently in India. The highly transmissible nature of the variant and its ability to cause breakthrough infections and reinfections, and the fact that people with no travel history or contact with international passengers have tested positive for the virus should alert policymakers to take the Omicron threat seriously.