“The corona disease has been eliminated thanks to God,” Mr Magufuli told worshippers in a church in the capital, Dodoma.
The World Health Organization (WHO) has expressed concern over the government’s strategy on Covid-19.
The government has stopped publishing data on the number of coronavirus cases in the country.
On 29 April, the last day official data was released, there were 509 cases, with 21 deaths in Tanzania. However, Mr Magufuli said last week that only four patients were receiving treatment in the largest city, Dar es Salaam.
Last month, Tanzania’s government dismissed a US embassy warning that hospitals in Dar es Salaam were “overwhelmed” and that the chances of contracting the virus was “extremely high”.
Mr Magufuli has repeatedly said the health crisis has been exaggerated and urged people to attend services in churches and mosques, saying that prayers “can vanquish” the virus.
There is no scientific proof that the tonic works and the WHO has urged people not to use unproven medication.
Opposition politicians have criticised Mr Magufuli in the past for promoting policies that could harm the health of Tanzanians.
The head of Tanzania’s medical association, Elisha Osati, backed the government in a recent BBC interview, saying that hospitals were operating as normal and that the majority of coronavirus inpatients were suffering from mild symptoms.
Mr Magufuli has accused the country’s health officials of exaggerating the coronavirus crisis. He has also ridiculed the strict measures neighbouring countries have imposed to fight the pandemic.