Effectiveness of the Pfizer-BioNTech and Oxford-AstraZeneca vaccines on covid-19 related symptoms, hospital admissions, and mortality in older adults in England: test negative case-control study.
BMJ. 2021 May 13;373:n1088. doi: 10.1136/bmj.n1088.
BMJ. 2021.
PMID: 33985964
Free PMC article.