Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Summary of the number of studies by the World Health Organization’s region classification.
| World Health Organization’s region classification | Countries of origin | Studies, n (%) |
| Eastern Mediterranean | Qatar | 1 (2.2) |
| Europe | France, Germany, Italy, Luxembourg, Spain, Switzerland, the Netherlands, and the United Kingdom | 12 (26.1) |
| Southeast Asia | China | 1 (2.2) |
| North America | Canada, the United States | 26 (56.5) |
| Western Pacific | Australia, Japan, South Korea | 6 (13) |
