PMC:7210464 / 421-602 JSONTXT

{"project":"LitCovid-PD-CLO","denotations":[{"id":"T1","span":{"begin":27,"end":39},"obj":"http://purl.obolibrary.org/obo/OBI_0000968"}],"text":" 2 weeks prior are used as instrumental variables for causal inference. Stringent quarantines, city lockdowns, and local public health measures imposed in late January significantly"}