Getting COVID may offer some natural protection, known as natural immunity. Current evidence suggests that reinfection with the COVID virus is uncommon in the first 90 days after initial infection. However, experts don’t know how long this protection lasts, and the risk of severe illness and death from COVID far outweighs any benefits of natural immunity. Receiving a vaccine after having COVID is like a booster effect, and a significant layer of protection to any natural immunity you may have built.
A study published in August 2021 indicates that if you had COVID before and are not vaccinated, your risk of getting reinfected is more than two times higher than for those who were infected and got vaccinated afterwards. Plus, getting vaccinated provides greater protection to others since the vaccine helps reduce the spread of COVID.
SOURCE: https://www.bu.edu/articles/2021/myths-vs-facts-covid-19-vaccine/ (Boston University)