Omicron less lethal than Delta variant, say British health officials
People who contracted the omicron variant of the coronavirus were about half as likely to need hospital care as those infected with the Delta variant, and one-third as likely to need emergency care, according to a report issued on Friday by British health officials.
The analysis of public data also found that vaccination offers strong protection against hospitalisation and severe illness following omicron infection, helping prevent the worst outcomes even as infection rates in Britain soar to record levels.
The findings represent some of the largest sets of real-world data to be released since the highly contagious variant was first discovered in late November, and adds to a growing body of evidence that omicron may not present as great a danger of hospitalisation and severe illness to the public as earlier variants.
“The latest set of analysis is in keeping with the encouraging signs we have already seen,” said Susan Hopkins, the chief medical adviser at the health security agency.
The risk of being admitted to a hospital for omicron cases was 65 per cent lower for those who had received two doses of a vaccine, compared with those who had not received any vaccination.
The rate of hospitalisation was even lower among those who had received three doses of vaccine, according to the report, which was issued by the UK Health Security Agency. People who had received booster doses were 81 per cent less likely to be admitted to the hospital, compared with unvaccinated people, according to the agency.
The agency analysed 5,28,176 omicron cases and 5,73,012 Delta cases between November 22 and December 26 to assess the risk of hospitalisation in England.
The researchers included all cases diagnosed in the community and then assessed the risk of general admission to the hospital or admission through emergency care.
In a second study, the agency examined just symptomatic cases, linked with hospitalisation data, and found that three doses of a vaccine reduced the risk of hospitalisation for people with the omicron variant by 88 per cent, compared with unvaccinated people with that variant.
While the results were encouraging, the agency said it would take more time to assess the severity of omicron infections after admission to the hospital.
Nicholas Davies, an assistant professor of mathematical modelling at the London School of Hygiene and Tropical Medicine, cautioned that the report covered mostly a younger mix of patients.
“The omicron wave is starting in younger people,’’ he said in an interview.
“It’s important to bear in mind that we don’t have much data on risks in older people yet.”
But he added the findings were still encouraging, saying: “It does look like people are experiencing less severe outcomes.’’
Health officials have noted that omicron presents a challenge because of the sheer speed at which it is moving through the public. Vaccines are less effective at preventing infections than had been the case with other variants, according to the findings.
“Vaccine effectiveness against symptomatic disease with the omicron variant is significantly lower than compared to the Delta variant and wanes rapidly,” according to the report.
“Nevertheless, protection against hospitalisation is much greater than that against symptomatic disease, in particular after a booster dose, where vaccine effectiveness against hospitalisation is close to 90 per cent.”
New York Times News Service