NSF has issued a Dear Colleague Letter in response to the COVID-19 virus which can be found at:
Additionally they have released a FAQ regarding the virus and its effect for proposers and awardees
Frequently Asked Questions (FAQs) About the Coronavirus Disease 2019 (COVID-19) for National Science Foundation (NSF) Proposers and Awardees
Finally, NSF has issued a letter inviting RAPID proposals to respond to the virus.
If you are interested please read the letter to researchers.