How does natural immunity work and are there ongoing studies to determine if it provides more protection or less than immunization? What is the risk of getting COVID-19 if you are vaccinated? Boosted? Have had prior COVID-19 infection? All of the above?
After recovering from a COVID-19 infection, most people have immunity that provides very good protection against re-infection for at least three months, and excellent protection from severe re-infection. Studies comparing protection gained by prior infection versus protection generated from vaccination generally show that they are similarly effective, depending on which vaccine was used and the number and timing of doses. People who have been both vaccinated and had prior infection have the highest levels of protection. Prior infection status has not been used as a confirmation of protection because many studies showed considerable variability in protection depending on the severity of the initial infection, whereas the protection from vaccination is more predictable. In addition, antibody tests have not always been reliable at confirming prior infection.
— Steve Lawrence, MD, infectious diseases specialist.
If I’ve had COVID-19 in the past few months, do I still need to get tested and stay home if I have symptoms (presuming it is another cold-causing virus and not SARS-CoV-2?)
We currently do not require you to be tested if you have had COVID-19 within the last 90 days. However, at this time, depending on your symptoms, we may recommend testing for influenza. It is always best to call the COVID-19 Exposure/Illness Hotline at 314-362-5056 to get advice if you have symptoms.
— Eva Aagaard, MD, interim senior administrator for Occupational Health.