There is a lot of discussion about whether #coronavirus infection will result in long-term #immunity. We don't yet have data on this, but in the meantime, a brief discussion of some types of immunity that we might see. (thread)

1. Sterilizing immunity--this is the best-case scenario. Sterilizing #immunity means that the body is able to prevent reinfection entirely. Viruses may enter the body, but they are unable to infect cells, replicate, or otherwise cause harm or further spread.

2. Immunity with limited viral replication. This would mean the people could get reinfected but it would involve lower levels of virus production. This often has important benefits for both decreasing severity of illness and limiting spread of infection to others.

3. Immunity with decreased symptom severity. People may be able to get reinfected and produce high levels of viruses, but they would not have as severe an illness or might not be ill at all. This is very helpful to individuals and could still reducing spread (e.g. less sneezing).

4. Immunity with decreased transmission but no change to symptoms. People may still get ill, but the immune response would limit the production of infectious viral particles. This would be helpful for #PublicHealth but not individuals.

We don't yet know which, if any, of these types of immunity will result from infection with #SARSCoV2. Based on data from other coronaviruses and animal models, we think there will be immunity of some sort. We don't know how long it would last. That's another kettle of fish.

The goal in #vaccine development is usually sterilizing immunity, but it can be hard to achieve. However, even a vaccine that doesn't provide sterilizing immunity could have significant benefits.