A study published in January 2022 evaluated the risk for newly diagnosed diabetes after infection with Covid-19 between March 1, 2020, and June 28, 2021, among persons aged less than 18 years. The data came from two U.S. medical claims databases, IQVIA and HealthVerity.

A group consisted of individuals with a diagnosed Covid-19 infection who were assessed for the risk of a new diagnosis of diabetes (type 1, type 2, or other diabetes) within 30 days of a diagnosis of a Covid-19 infection (Covid-19 individuals).

The other group consisted of individuals without a diagnosis of a Covid-19 infection between March 1, 2020, and June 28, 2021, and assessed for the risk of a new diagnosis of diabetes (Non-Covid-19 individuals).

All individuals had to be continuously enrolled in the medical systems throughout the study period.

Q: What type of study/report would best describe this study/report?

1. Case report
2. Ecological study
3. Cross-sectional study
4. Cohort study
5. Case-control study
6. Randomized controlled trial
7. Meta-analysis

Briefly explain the rationale for your answer: