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Sterilizing immunity would be a best-case scenario. It describes an immune system that is armed against a foe, able to fend it off before infection can take hold. Diseases that we think of as “one-and-done” infections induce such a robust and durable immune response in a single encounter that we cannot be reinfected.
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Functional immunity, on the other hand, may be within reach. In fact, it’s the scenario Menachery sees as most likely.
Under this scenario, people whose immune systems have been primed to recognize and fight the virus — whether through infection or vaccination — could contract it again in the future. But these infections would be cut short as the immune system’s defenses kick into gear.
Waning infection, the third scenario, is a variation of functional immunity. In this scenario, people who have been infected or vaccinated would lose their protection over time.
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Lost immunity describes a scenario in which people who have been infected would lose all their immune munitions against the virus within some time frame. A reinfection after that point would be like a first infection… None of the experts who spoke to STAT felt this was a possibility.
