WASHINGTON - U.S. officials believe as many as 20 million Americans have contracted the coronavirus, suggesting millions had the virus and never knew it.That’s nearly 10 times as many infections as the 2.3 million cases that have been confirmed and comes as the Trump administration works to tamp down nationwide concern about the COVID-19 pandemic as about a dozen states are seeing worrisome increases in cases.RELATED: WHO expects the world will reach 10 million coronavirus cases 'within the next week'The administration also looks to get its scientific experts back before the public more as it tries to allay anxieties about the pandemic while states begin reopening.