Two US counties will receive a surge of free, rapid, at-home Covid-19 tests in an effort to study how people use them and how that impacts Covid-19 trends in the community, according to an announcement Wednesday by the National Institutes of Health. The project – called “Say Yes! COVID Test” – will roll out 2 million antigen tests to as many as 160,000 people across two locations: Pitt County, North Carolina, and Chattanooga/Hamilton County, Tennessee. Each household will receive 25 tests, which is enough to test two people per household three times a week for up to a month. “This testing initiative is the first of this scale to attempt to make free, rapid, self-administered tests available community-wide in order to determine their effectiveness in our nation’s comprehensive response to the COVID-19 pandemic,” NIH Director Dr. Francis Collins said in a statement Wednesday. “We hope to gain foundational data that can guide how communities can use self-administered tests to mitigate viral transmission during this and future pandemics.” In collaboration with the US Centers for Disease Control and Prevention, researchers will capture anonymous data from the tests, plus measures of Covid-19 in those two cities. According to a website for the initiative, they “will study factors like test positivity rate, COVID-19-related illness and hospitalizations, and measurements of viral particles in sewage wastewater.” “We’re trying to evaluate in their day-to-day lives how consumers, when provided access to testing, rely on it to make a decision on what behavior is responsible,” Dr. Vik Kheterpal, whose company, CareEvolution, created the digital tool that accompanies the at-home tests, told CNN Wednesday. At-home antigen tests like the one in this study look for active infection by detecting viral proteins. Results are not impacted by a vaccine, and in some cases confirmatory testing may be recommended using a separate PCR test, which looks for the virus’ genetic material. The test being used by the initiative, Quidel’s QuickVue test, gives results from a nasal swab in about 10 minutes, using technology similar to a pregnancy test. The US Food and Drug Administration announced earlier this month it had authorized the test for emergency use. Experts have long been calling for a wider rollout of cheap, accessible tests across the US in an effort to better screen and diagnose Covid-19. Another recent study estimated that mailing rapid antigen tests across the US to encourage frequent, widespread testing could be a cost-effective way to prevent millions of infections and thousands of deaths over a couple of months.