FIGURE 1.
Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram [73]. CENTRAL: Cochrane Central Register of Controlled Trials; WHO: World Health Organization; COVID-19: coronavirus disease 2019.
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.