PMC:7537225 / 37650-37805 JSONTXT

{"project":"LitCovid-sentences","denotations":[{"id":"T278","span":{"begin":0,"end":155},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"Second, it would not have been possible to use an experimental design, so all our findings are correlative, and we cannot put forward causal relationships."}