We have a number of studies that are looking at what the duration of protection is, not only from natural infection, as I stated earlier, but also from vaccines, and in different types of populations. We just supported a number of studies that are looking at, for example, immunocompromised populations and populations with chronic illnesses. We're looking to see the extent to which vaccine protection differs in those at-risk communities.
On May 3rd, 2021. See this statement in context.