请问，移民签证申请人的健康保险，是签证前买还是登陆美国以后买？
-It seems this rule was suspended by a judge.
See:
https://www.wenxuecity.com/news/2019/11/03/8825444.html
Just contact NVC to see whether the health insurance is required for the immigrant visa application a couple of days later.
