How good are Covid tests against new variants? The use of rapid Covid tests has soared this year with the spread of omicron and free shipments organized by the Biden Administration. But in August the US Food and Drug Administration cautioned that people who get a negative result should still repeat the test a couple days later. That communication has led to a lot of confusion — especially when combined with increasing anecdotal reports of false negatives from rapid tests. Does that mean the tests don’t do a good job at detecting the latest variants, including the ultra-transmissible BA.4 and BA.5?  Read more from Bloomberg