Vaccine-induced immunity has been shown to offer much broader protection than natural post-infection immunity, and reinfections are not rare with Delta.
Here's a recent study : https://twitter.com/OYCar/status/1412656966481039367?s=20
1) A report in Nature that the natural immunity produced in people who have already had covid may last a lifetime. https://www.nature.com/articles/d41586-021-01442-9
2) The Cleveland Clinic--consistently regarded as one of the top hospital systems in the United States and in the world--recently shared a study of 52,238 patients showing zero incremental benefit from the jab to the previously infected, recommending that "people who’ve had COVID-19 don’t need to get vaccinated." https://www.healthline.com/health-news/new-study-determines-...