Amid massive shortages, Amazon is only allowing hospitals and government agencies to order items like N95 masks and COVID-19 diagnostic kits. Now, third-party sellers on Amazon are stepping up to help, and repositioning their small businesses to survive the pandemic. CNBC talked to sellers who pivoted rapidly to supply healthcare providers and first responders with everything from masks and gowns from China to hand sanitizer made with leftover ingredients for toy putty.

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