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.
Study flow chart. We defined the before and during mild lockdown periods in our questionnaire as follows: (1) In 2020, before lockdown—March–June 2019, during lockdown—from March 2020 to during the survey (July–November 2020); (2) in 2021, before lockdown—October–December 2019, during lockdown—October–December 2020.
