At least 40,000 people could die with coronavirus in South Africa by the end of the year, scientists have warned.
The projections were made by a group of academics and health experts advising the government.
They assume tough lockdown restrictions will be eased from June, as President Cyril Ramaphosa has announced.
The curbs - which were introduced in March and include a ban on tobacco and alcohol sales - have been credited with slowing the spread of the virus.
The country of 57 million people has recorded just 17,200 cases of Covid-19 and 312 deaths linked to the disease so far. Spain, by comparison, has reported about 278,000 cases and almost 28,000 deaths for a population of only 47 million.
But the projections by the South African Covid-19 Modelling Consortium - set up to help government planning over the outbreak - says the country could experience a sharp rise in cases and deaths over the coming months.
The report was released during a meeting with Health Minister Dr Zweli Mkhize following criticism of the government's perceived lack of transparency.
The predictions are subject to change as more data becomes available, and assume the current restrictions will be relaxed from 1 June.
Under an "optimistic scenario", by late August the number of active cases could reach almost 100,000, before declining. The cumulative number of deaths by November would be 40,000.
Under a "pessimistic scenario" the number of active cases could peak around at 120,000 in August, and a total of 45,000 would die by November.
The report also suggests there could be 1.2 million Covid-19 cases in total, and intensive care units could be overwhelmed within weeks.
South Africa's balancing act
By Nomsa Maseko, BBC News, Johannesburg
The politics of Covid-19 and scientific rivalry have intensified in South Africa. The opposition Democratic Alliance is taking the government to court, arguing that the stringent lockdown regulations are unwarranted and the ban on alcohol and tobacco sales should be lifted.
The government itself is not speaking with one voice. This month President Cyril Ramaphosa said lockdown regulations would be eased from "level 4" to "level 3" to allow schools to reopen and more people to return to work from early June.
But Health Minister Zweli Mkhize seems reluctant, and has said that according to the World Health Organization, South Africa is not yet ready for level 3 because infections continue to rise every day.
It's a balancing act for the government, which has to take the issues of food security, job losses and the economy into consideration. Some scientists have called on the government to fast-track lockdown restrictions to level 2, claiming the current ones have little or no effect on the spread of coronavirus.
In March, President Ramaphosa imposed some of the strictest lockdown measures of any country.
Most workers were ordered to stay at home. In addition to the tobacco and alcohol bans, jogging, cycling and dog-walking were also prohibited.
On 1 May, the curbs were eased from "level 5" to "level 4", allowing people to exercise between 06:00 and 09:00.
People are still urged to wear face masks in public and observe social distancing rules.