This week a large study on vaccination and previous infection, in other words natural immunity, was published by CDC based on data from New York State and California. They looked at COVID 19 infections and hospitalizations in patients who have been vaccinated with different vaccines as well as those who had natural immunity.
Channel announcement at the end of the video
CDC study: https://www.cdc.gov/mmwr/volumes/71/w…
Natural immunity systematic review: https://youtu.be/64OTXmp3YRI