2.4. Eligibility Criteria
Case report and case series studies on the development of acute abdomen
in persons older than 18 years following COVID-19 vaccination were
included. Other types of studies such as systematic reviews, narrative
reviews, letters to the editor, congress or conference abstracts,
editorials, interviews, commentaries, short communications, brief
reports, and newspaper articles were excluded. In addition, we excluded
records that reported patients younger than 18 years of age and
incorrect outcomes (Other type of outcomes). We also excluded records
that were not in English, Portuguese, or Spanish.