The Omicron wave in New York looks worse than in England

Since it was discovered in southern Africa in late November, the Omicron variant of SARS-CoV-2 has been detected in 114 countries. It is now dominant in at least 41, including America and Britain. The new variant is estimated to be about twice as infectious as Delta; a huge wave of cases threatens to engulf health-care systems around the world. America recorded 4.9m new covid-19 infections in the week to January 9th, nearly three times the previous record set in January 2021.

Through sheer dint of evolutionary fortune Omicron causes a less severe form of disease than Delta. That is because it tends to remain in its host’s nose rather than entering their lungs. A study by Britain’s health-security agency published on December 23rd found that people with Omicron were 55-69% less likely to need hospital care than those infected with Delta. These results need to be interpreted with caution. The study did not account for past infections that went undiagnosed, meaning some of the reduced severity is likely to be because many of those contracting it had unknowingly caught covid before.

But a variant that causes severe disease at half the rate of Delta and twice as many infections in total will cause about the same number of severe cases. Hospitals in many countries are feeling the strain. In America, the number of covid patients is nearing the record set in January 2021. Anthony Fauci, the White House’s chief covid adviser, expects cases to continue rising for weeks to come. In England, the defence ministry announced on January 7th that it had begun deploying 200 army personnel to London hospitals to help manage the caseload, which is currently about half of last January’s peak. The country’s health service has been hit by worker shortages: about 4% of staff were absent because of covid in the week to January 2nd.

But London, one of the first big Western cities to be hit with Omicron, is showing positive vital signs. Infections in the capital—which reached an eye-watering one-in-ten of the population on Christmas Day, according to a representative sample—have peaked. Although the sheer volume of cases has led to a 170% rise in hospital admissions over the past month, the number of patients requiring intensive care has increased by only 20%. Deaths are currently at just 13% of last year’s peak.

Data from New York state suggest America may not fare so well. Both London and New York have relatively young populations with high levels of immunity from infection and vaccination (about 80% of adults in both places have had at least two shots or a one-shot regimen). But in contrast to England, in New York the number of covid patients requiring intensive care has moved hand-in-hand with cases, and deaths are rising too (see chart). England’s leaders eased restrictions amid a wave of infections in July 2021, hoping that the country would benefit from higher immunity come winter. That immunity, along with a quick booster campaign, may have made the difference. In New York some 13m people have completed the initial regimen but only a third of adults, some 5m, have had booster shots.

Many vaccine sceptics point to the milder disease caused by Omicron and the fact that vaccines do not completely prevent either transmission or reinfection as evidence of the jabs’ redundancy. Yet a study of around half a million Omicron cases in England found that the risk of hospitalisation was 81% lower for those who had had three vaccine doses, compared with those who had had none. The virus may have mellowed, but it is still deadly for many of those who think they can fight it alone. ■

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