Presidential Proclamations begun by President Trump and expanded by President Biden have prohibited most travelers to the U.S. if they have been in listed countries within the 14 days preceding their entry or visa application. The countries have included the Schengen area (Europe), U.K., and Ireland, India, South Africa, Brazil, China, and Iran. The U.S. has been considering individual requests for "national interest exception" (NIE) to these bans. Under the plans, all of that would stop for fully vaccinated travelers.
It is not clear exactly which vaccines and what kinds of proof of vaccination will be acceptable. One could expect that the vaccinations currently approved for full or emergency use in the U.S. (Pfizer/BioNTech, Moderna, Johnson & Johnson) and most other countries (AstraZeneca) will be accepted. Less clear is whether vaccines produced in India, China, and Russia that have been reported to be less effective would be accepted.
It is not clear whether "expanded contact tracing" – probably involving airlines collecting and making available to the U.S. Centers for Disease Control additional information about passengers' names, phone numbers, email addresses, and physical addresses in the U.S. – will apply only to passengers who would have been subject to the country-specific bans or to a larger array of passengers.
This development will not resolve the problem of unavailability of visa appointments at U.S. consulates around the world due to backlogs from past consular closures and limited staffing and due to continued staffing restrictions arising from COVID-19. Under this exemption, a huge amount of pent-up demand from previously banned, now vaccinated travelers will initiate visa applications to U.S. consulates that will be unable to process them timely in many instances. But travelers with existing valid visas and those able to use the Visa Waiver Program for visits will be able to skip the NIE hurdle on travel.
Travelers can expect continuation of the current requirement for all travelers to the U.S. to obtain a negative COVID-19 test within three days of departure to the U.S.
Obviously, more details will be announced, but this provides strong incentive for aspiring travelers to obtain vaccination with acceptable proof.