As the rates of Covid-19 infection in several countries slow, governments are increasingly concerned with how best to ease lockdown rules without inviting a second wave of the contagion. Antibody tests, designed to identify people who have built up immunity to the infection, will be crucial to making this work. Just three commercially-produced blood tests have so far gained US emergency use authorisation, but last week Abbott launched one in the US – without the FDA’s authorisation – and Roche is talking up the arrival of its antibody test, slated for early May. The Elecsys Anti-Sars-CoV-2 serology test is intended to run on Roche’s cobas instruments, which are capable of processing up to 300 tests per hour. Like Abbott, Roche is working towards an EUA for its antibody test as well as seeking EU authorisation, and is aiming to make tens of millions of tests by June. But there is a risk that the FDA’s light touch here could flood the market with poorly performing assays that could deliver inaccurate results. Earlier this month the FDA said more than 70 groups had notified it that they had antibody tests available. Quality control will be paramount.