United States companies are scrambling to boost production of coronavirus tests increasingly in short supply as Covid-19 cases soar and schools and employers revive surveillance programs that will require tens of millions of tests, according to industry executives and state health officials.

Test manufacturers including Abbott Laboratories, Becton Dickinson and Co, and Quidel Corp in recent months scaled back production of rapid Covid-19 tests, which can produce results on-site in minutes, as well as test kits that are sent to laboratories for analysis. The move followed a nearly 90 per cent decline in testing and a similarly large drop in Covid-19 cases in the United States.

Now, with the Delta variant pushing US Covid-19 cases well above 100,000 per day, test makers are working to quickly reverse course, industry executives and state officials told Reuters.