The question “is a single jab even necessary for people who have recovered from Covid?” never seems to get asked in these articles. Curious.
A few recent studies mentioned here:
https://twitter.com/profshanecrotty/status/1408186201257828356
“... Reported natural immunity protection against any SARS-CoV-2 re-infection ranges from 81-99.8% over 7-8 months (1-3,5) (though a concerning drop was observed in persons > 65 years old in Denmark (4)). “