Risk of mortality in patients infected with SARS-CoV-2 variant of concern 202012/1: matched cohort study

Dear Editor
Consistent with past findings, mortality rates in the data reported for this study differ widely across age groups (e.g., 0.11% in 30-59 year olds to 12.64% in over 80s). However, the data reported does not include CFR by age group for S gene positive vs. S gene negative. There are two reasons this information is important. First, it is practically important to know whether the variant changes the differences in CFR across age. Second, if the variant changes the CFR more in some age groups than others (i.e., there is an interaction between S gene positive/negative and age group), there are implications for the confidence intervals reported. If, for example, the increase in the overall CFR within the S gene negative group was caused by larger CFRs in older groups, the confidence intervals around the overall CFR would necessarily be wider due to the smaller sample size of older groups. A test of the interaction between S gene positivity/negativity and age would provide initial evidence about whether this is likely to affect conclusions.