On Dec 13, 2021, the UK Health Security Agency (UKHSA) confirmed that a patient in England had died after contracting the omicron variant of SARS-CoV-2. The previous day, prime minister Boris Johnson launched a drive to offer all adults in the UK a third dose of the COVID-19 vaccine by the end of the year.“We are now facing an emergency”, stated Johnson.“There is a tidal wave of omicron coming and I am afraid it is now clear that two doses of vaccine are simply not enough.” WHO categorises the risk associated with omicron as very high. The new variant, which is also known as B. 1.1. 529, was identified in November, 2021. It has since been detected in more than

60 countries. As The Lancet Respiratory

Medicine went to press, the UK had registered 10 017 cases of omicron. The true caseload is likely to be considerably larger. On Dec 15, 2021, 78 610 people tested positive for SARS-CoV-2 in the UK.“There will be an increasing number of omicron patients going into the NHS, going into hospital, going into intensive cares”, cautioned Chris Whitty, England’s Chief Medical Officer.“That will begin to become apparent, in my view, fairly soon after Christmas.” In the week ending Dec 12, Africa recorded 196 000 cases of COVID-19, an increase of 86% on the previous week. Cases of COVID-19 rose by 66% in South Africa, where omicron was first detected. But bed occupancy rates in the country’s intensive care units remain low. The original strain of SARS-CoV-2 has an R0 of 2· 5, while the delta variant (B. 1.617. 2) has an R0 of just under 7. Martin Hibberd, professor of emerging infectious diseases at London School of Hygiene & Tropical Medicine (London, UK), reckons omicron’s R0 could be as high as 10. In the UK, cases of omicron are doubling every 2–3 days, which puts it on track to supplant delta as the dominant variant in the country by mid-December. It also complicates control efforts.“Contact tracing works well if you have about a week between