The five filed a complaint at Lanka police station, alleging that their eyesight was affected after they were administered the injection, said SHO Sanjiv Mishra.
After the complaint was received, the SHO said, they were sent to the Varanasi Chief Medical Officer (CMO) for medical examination.
The CMO has constituted a medical board to probe the matter. They board has been asked to submit its report at the earliest.