A study published in the medical journal Lancet, reported that the Omicron infection had 2 day shorter symptom duration compared to the Delta variant.

According to the Zoe COVID app (COVID Symptoms Study App), which collects data on self-reported symptoms, there were 25% less chances of hospitalization due to the symptomatic Omicron infection than the Delta. The study used its unique analysis method as it collected data from only the vaccinated individuals which allowed it to control any distortions induced by disparities in vaccination status.

More than 5,000 patients were enrolled and examined in two sets of data. The first set considered data collected during the predominance of Delta variant and the second data from the recent Omicron wave which accounted for more than 70 per cent of cases. The patients in each group were compared 1:1 with a person of the same age, sex, and vaccination dose in the other group.

The difference in symptom duration between Omicron and Delta was more significant in individuals who received three vaccination doses. Symptoms lasted for an average of 7.7 days during the Delta-dominated period and only for 4.4 days, which was 3.3 days shorter, during the Omicron-dominated period. Among those who received only two vaccine doses, Delta symptoms lasted for 9.6 days while Omicron symptoms lasted for 8.3 days, a difference of only 1.3 days.

(Reuters, April 08, 2022)