There are currently no program restrictions related to the Covid-19 pandemic.
There are however, very specific travel restrictions and requirements for entry that can be found here: https://travel.state.gov/content/travel/en/international-travel/emergencies/covid-19-faqs-for-travel-to-the-us-information.html
You are responsible for meeting the travel requirements as mandated by the US government. If you do not meet them, you will not be allowed to enter the country