That wouldn't significantly affect the conclusion though, right? They compared the reinfection rate for people with previous infection + vaccine to people with

That wouldn't significantly affect the conclusion though, right? They compared the reinfection rate for people with previous infection + vaccine to people with previous infection + no vaccine. Since both groups previously had COVID, shouldn't that cause (in expectation) the same false positive rate for both groups when testing for reinfection? Edited to add: The authors cite [0] to support their claim that it's not significant, it basically seems consistent with their claim that it's really unlikely to still have viral shedding at the duration that they tested at. Also worth mentioning that adding an equal proportion of false positives to both groups would cause the study to understate the effect size (i.e. the magnitude of the additional protection conferred by vaccines) by biasing the odds ratio in the direction of 1. [0] https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(20)30172-5/fulltext https://www.thelancet.com/journals/lanmic/article/PIIS2666-5...