The Indian Council of Medical Research has constantly been studying the vaccine's efficacy. It has come with multiple conclusions about how efficient Covaxin/Covishield/Sputnik V is and worked on the efficiency when one dose of Covaxin is taken followed by a second dose of Covishield and vice versa.
The ICMR has discovered in their most recent study that anyone affected with Covid19 before taking a jab of whichever vaccine can take one dose of Covaxin alone to guarantee themselves covid immunity. This research was conducted on more than 100 healthcare workers, and few medical experts were a part of this test from February To May 2021. These people who were administered only a single dose of Covaxin showed exact immunological response to those who took two jabs to get covid free.
This study of how the reactions of these two groups are similar has been explained in the most detailed manner in a journal published in the Indian Journal of Medical Research and was titled 'Antibody responses to the BBV152 vaccine in individuals previously infected with SARS-CoV-2: A pilot study.'
Many such studies have been emerging that a single dose of the vaccine might be more than enough against covid, but few studies have also indicated this to their need of a booster dose sometime in the future, whereas it is not the case with someone who has taken two doses. However, with the ICMR and CCMB studying the effect of vaccines on the Delta Variant that is already set in India, new studies will emerge as the country enters a timeline of the predicted third wave.