Vaccination is not a guarantee against the Covid-19 infection and it will only ensure that the infection does not become severe, a preliminary study conducted by the All India Institute of Medical Sciences, New Delhi has claimed .
AIIMS has studied a small sample of 63 people. Out of these 63 people. 35 received both the dose of vaccines and 27 received only one dose. All of them got breakthrough infections (infections after vaccination) and among the samples which were genome sequenced, the Delta variant — the variant first reported in India — is predominant. Read more here

https://www.google.co.in/amp/s/www.hindustantimes.com/india-news/delta-covid-19-variant-can-infect-vaccinated-people-claims-aiims-study-101623307391151-amp.html