Please be advised that the International Maritime Organization (IMO) has set up a page on its website for COVID-19 advice, which can be found here:

http://www.imo.org/en/MediaCentre/HotTopics/Pages/Coronavirus.aspx

It contains a list of Circular Letters with COVID-19 related notifications received from IMO Member States (updated weekly):

http://www.imo.org/en/MediaCentre/HotTopics/Pages/COVID-19-Member-States-Communications.aspx

From this you will find that some states have issued guidance on extension of certificates (for example, Panama has extended the validity of all statutory certificates (except for Conditional Certificates) expiring between March and May 2020 for a period of three months) as well as port measures, and you are encouraged to consult this IMO page for information and guidance.