Multiple SARS-CoV-2 vaccinations have shown excellent efficacy during clinical trials. However, post vaccine surveillance is important to confirm ‘real-world’ findings of vaccine efficacy and safety. It is therefore imperative to identify individuals that become infected with SARS-CoV-2 post vaccination. We investigated the vaccination status of staff that had tested positive in a cohort of healthcare workers in one large tertiary hospital in the UK. At the time of the investigation, 8th December 2020 to 13th March 2021, 11,871 staff had been vaccinated and 225 staff tested positive for SARS-CoV-2. This period coincided with the second wave of SARS-CoV-2 infections in the UK which was driven by the Alpha variant. No healthcare workers who were double vaccinated had a positive PCR test for SARS-CoV-2 during this study period confirming vaccination with Pfizer BioNTec BNT162b2 gives excellent protection against infection of this variant.