Jan. 5, 2022 – People vaccinated against COVID-19 are two-thirds less likely to be hospitalized because of the Omicron variant than those infected with the earlier Delta variant, a new study says.
The risk for adults of being admitted to hospital with Omicron was about one third of that for the Delta variant, the U.K. Health Security Agency said in a briefing.
The analysis also found that the risk of needing emergency care or being admitted to a hospital with with Omicron was about half of that for Delta.
Latest figures from the U.K. showed there were 14,210 patients hospitalized in England with COVID-19 by Jan. 3, the highest since Feb. 20 last year, but lower than the peak of 34,336 recorded in January 2021.
The latest U.K. data confirmed that all COVID-19 vaccines continued to be less effective against symptomatic infection from Omicron compared with Delta.
Among those who had received two doses of the Pfizer or Moderna vaccines, effectiveness dropped from around 65-70% to around 10% 20 weeks after the second dose.
Two to 4 weeks after a booster dose, vaccine effectiveness ranged from around 65-75%, dropped to 55-70% at 5 to 9 weeks, and 40-50% from 10 weeks or more after a booster dose.
The U.K. Health Security Agency worked with the Cambridge University MRC Biostatistics unit to analyze 528,176 Omicron cases and 573,012 Delta cases through Dec. 26.
The data suggests that three doses of vaccine provided an estimated 68% drop in the risk of being hospitalized with Omicron compared with people who were unvaccinated.
One dose of any vaccine was tied to a 35% reduced risk of hospitalization among symptomatic cases with the Omicron variant, two doses with a 67% reduction up to 24 weeks after the second dose, and a 51% reduced risk 25 or more weeks after the second dose when compared to people who had not received a vaccine.