PMC:7784828 / 4759-4897 JSONTXT

{"project":"LitCovid-sentences","denotations":[{"id":"T50","span":{"begin":0,"end":138},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"Despite many attempts to design effective vaccines, none has been successful at providing long-lasting benefits at a population level [9]."}