Office for National Statistics, Coronavirus (COVID-19) Infection Survey, UK: 12 March 2021, 2021-03-12 ([Internet, 2021-05-06](https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/conditionsanddiseases/bulletins/coronaviruscovid19infectionsurveypilot/12march2021))