Bolsonaro told supporters outside the presidential palace that he had just visited the hospital and been tested.
The cities of Belem and Macapa at the mouth of the Amazon River emerged as major coronavirus hotspots in April and May. The virus has since spread deep into surrounding rural areas.
In the United States, which has over 116,000 deaths, testing is still ramping up months after the start of the outbreak.
On Saturday Brazil registered 35,930 total coronavirus deaths and 672,846 confirmed cases.
Brazil's Health Ministry reported late on Thursday that confirmed cases in the country had climbed past 600,000 and 1,437 deaths had been registered within 24 hours.
Thursday was the third straight day with a new daily high for Brazil's coronavirus deaths.
Brazil might soon trail only the United States in the number of coronavirus cases. Russia currently has the second-highest number of cases.
Nationwide testing in Brazil still lags far behind European nations. Brazil had processed nearly 338,000 novel coronavirus tests in official labs by the beginning of last week.
They sang the Brazilian national anthem in Tikuna, one of the 14 indigenous languages spoken in their ramshackle settlement on the outskirts of Manaus where 2,500 descendants of 35 different Amazon tribes live.
The president has argued that state and municipal governments have gone overboard in social isolation measures to restrict the disease's spread and that it is overly damaging to the economy.