Preliminary analyses of sequenced cases have been undertaken to compare the risk of hospitalisation, as defined by admission as an inpatient, or presentation to emergency care that resulted in admission, transfer or death, following BA.2 compared to BA.1. This analysis adjusted for age, reinfection status, sex, ethnicity, local area deprivation and vaccination status. It also controlled for the effect of geography and specimen date. The risk of hospitalisation does not appear higher following a BA.2 infection than following a BA.1 infection (hazard ratio 0.87, 95% CI: 0.75-1.00).
Although the central estimate indicates that the risk of severe outcomes for BA.2 may be lower than for BA.1, the variability of the data, as reflected by the confidence intervals, mean that it is not possible to conclude this with certainty. These results are preliminary, and it is possible that the estimates of the risk of hospitalisation may change as cases accrue.