Study registration: *
Publication Liu C, medRxiv, 2021
Dates: 2020-12-04 to 2021-09-21
Funding: Public/non profit (The National Library of Medicine/National Human Genomic Research Institute and the National Institute of Allergy and Infectious Diseases of the National Institutes of Health )
Conflict of interest: no COI (The authors declare no competing interest)
Description of participants: Adults including elderly and co-morbidities with no history of COVID-19 in multiple centres in New York, USA
Follow-up duration (months): 9.70
|Variant description :
Variant name: Delta|
Evidence: Indirect evidence (prevalence of variant in the population: 1 to 99%)
In addition to the preprint, the supplementary material were used in data extraction and risk of bias assessment. Authors used matching and adjustment to account for confounding. 78.8% received Pfizer/BNT162b2, while 21.2% received Moderna/mRNA-1273. The infections table (eTable 2) appears to have a date typographical error; it states after "June" 18, 2021 but the text and other figures indicate this should probably be after "January" 18, 2021.
Concerns over uncontrolled confounding, missing data on a confounder and (for infection outcomes) the possibility that controls would only be identified if they seek testing; in addition there are uncertainties over the possibility of selection bias in a test-negative design.