Predicting the future path of a highly infectious virus such as Covid-19 can inform crucial interventions to mitigate the risks posed by a widespread outbreak, chief among which is to limit infections and deaths, and a sudden influx of ill patients that could collapse the health system within weeks.

News24 understands that Dr Harry Moultrie is in charge of putting the team together. He is a senior medical epidemiologist at the Centre for Tuberculosis at the National Institute for Communicable Diseases (NICD).

The first projections were done by the head of the South African Centre for Epidemiological Modelling and Analysis (Sacema) Professor Juliet Pulliam and Jeremy Bingham, a master's student at Stellenbosch University who works for Sacema.

Their initial projections together with stark guidelines on what steps needed to be taken immediately, were presented to government by Dr Kerrigan McCarthy, head of the NICD's Division of Public Health, Surveillance and Response.

Professor Cheryl Cohen, head of the NICD's Centre for Respiratory Diseases and Meningitis, confirmed this week that a number of modelling efforts were underway.

"An expert group is being established to coordinate efforts and review these models and their assumptions. Preliminary data from models will be released in the next few weeks," Cohen said.

The modelling to be undertaken now by local experts is part of a range of recommendations the NICD presented to the Ramaphosa government last week.

This was bolstered by an initial set of projections, which were rudimentary and static, which showed that anywhere between 87 900 and 351 000 people could die if 10% and 40% percent of the population were infected. These figures took into account a slow or inadequate response from government.

The terrifying reality

Using data from a variety of outbreak areas, including China, the Imperial College of London Covid-19 Response Team led by Dr Neil Ferguson, looked at non-pharmaceutical interventions to reduce the demand for healthcare and the rate of fatalities for the UK and the US.

Their report, published on Monday, identified two key ways this could be done – mitigation and suppression. Both presented severe challenges.

Suppression would be difficult, the paper states, as it would require people to effectively be cut off from one another until a vaccine could be found, which could take 18 months. And mitigation "which focuses on slowing but not necessarily stopping epidemic spread, reducing peak healthcare demand while protecting those most at risk of severe disease from infection".

"The global impact of Covid-19 has been profound and the public health threat it represents is the most serious seen in a respiratory virus since the 1918 influenza pandemic," the paper reads.

"In the (unlikely) absence of any control measures or spontaneous changes in individual behaviour, we would expect a peak in mortality (daily deaths) to occur after approximately three months."

Under such circumstances, where government implements little to no measures and people continue daily life as normal, the paper predicted an 81% infection rate across the British and American population.

On Thursday, Health Minister Zweli Mkhize said it was possible that 60% to 70% of the population could be infected. He did not provide a time frame, but warned citizens to be ready and to actively take steps to fight the spread of Covid-19.

News24 reported on Friday that Ramaphosa and Cabinet had enacted the NICD's recommendations swiftly and a national disaster was declared last Sunday.

New models would take into account updated information about the coronavirus, and include more detailed analysis on co-morbidity factors such as the country's large percentage of people living with HIV and AIDS, tuberculosis and other chronic illnesses.

Global models

Around the world this week leaders announced stringent new measures designed to curb the rate of infection of Covid-19 – mostly driven by projections similar to what local experts are working on.

In the US state of California, Governor Gavin Newsom ordered 40 million people to "shelter in place", essentially an order for people to stay inside their homes.

In a letter to President Donald Trump, Newsom said the state predicted 25 million people would be infected.

In New York State, Governor Andrew Cuomo said he was opposed to a shelter in place order, as it would cause widespread panic. He told the New York Times podcast The Daily he was considering other measures - such as the closure of all businesses.

In the UK, Prime Minister Boris Johnson, acting on the Imperial College of London report that predicted as many as 500 000 people could die in Britain alone in an unmitigated epidemic, also started implementing stronger measures.

The same report also projected 2.2 million deaths in the US, prompting a sharp turnaround in the Trump administration's approach to the virus, the New York Times reported.

Ramaphosa last Sunday announced the closure of schools two days earlier than scheduled, initiated travel bans and banned gatherings of more than 100 people. Further measures were implemented throughout the week and efforts were under way to increase capacity for testing.

By Saturday, Mkhize had confirmed 240 infections in South Africa. No deaths had yet been reported.

The problem with mitigation, however, the Imperial College report said, was hospital capacity.

"Given that mitigation is unlikely to be a viable option without overwhelming healthcare systems, suppression is likely necessary in countries able to implement the intensive controls required."

Through a harsh system of suppression, China had by Friday succeeded in no new infections being reported for two days for the first time since the virus first broke out there in December.

China's approach included separating children from their families and forced quarantines as well as a massive effort to conduct as much testing as possible.

As of Thursday, South Africa had conducted little more than 6 000 tests in total, according to the NICD. Mkhize said he hoped the capacity for testing would be increased to 30 000 a day by mid-April.

News24