A health worker takes a swab from a man's nose through a glass shield (for safety) in New Delhi, India, on August 8, 2020. Rapid antigen tests for COVID-19 are being provided by the Indian government for free. Pradeep Gaur/SOPA Images/LightRocket via Getty Images Rapid, on-site coronavirus testing is generally less accurate than tests which are sent back to labs for analysis. But rapid COVID-19 testing is still a useful screening tool, especially if it's conducted frequently.