According to a study published in the journal PLOS Medicine, the COVID-19 vaccination can provide 60–94% protection against reinfection to individuals who have already been infected with SARS-CoV-2, depending on the variation.

In the study, researchers from the Katrine Finderup Nielsen laboratory at Statens Serum Institut, Denmark, used data from the Danish registry. The data set contained information on over 2 lakh people who tested positive for COVID during all three waves.

The findings of the study revealed that vaccination protected people against SARS-CoV-2, over and above the protection offered by natural immunity, during all three waves of variants. The researchers observed that in individuals who were infected with SARS-CoV-2, immunization offered up to 71%, 94%, and 60% protection against reinfection during the Alpha, Delta, and Omicron periods, respectively. They also observed that the vaccine protected people with the previous infection for up to nine months. 

(Source: https://theprint.in/health/covid-19-vaccination-provides-significant-protection-against-reinfection-study/1230811/ )