That's one of the most important issues we're facing now. These vaccines were authorized for emergency use with information from up to about three months. Obviously, we want a vaccine that lasts longer. There's a lot of work that's now ongoing to look at duration of protection and what we call vaccine effectiveness, as we're rolling them out in the real world situation. We are monitoring for vaccine effectiveness over time, so we can look at the durability of the immune response, as well as the immune response to the variants that are emerging.
On March 11th, 2021. See this statement in context.