Alumni Magazine #5_July 2020_single pages web

COVID-19 social distancing is tried and tested best practice - UJ mathematicians

played an important role in driving the infection in South Africa, especially in the initial stages of the pandemic. “The prevention of infections around the globe needs special attention due to improved mobility of humans. Particular attention needs to be focused on this group of people beyond the lockdown, to ensure that only COVID-19 negative cases are allowed into the country,” he said. Social distancing had also been required for outbreaks of other diseases, such as the Ebola Virus Disease (EVD), he added. “During the Ebola outbreak, educational campaigns, active case-finding and pharmaceutical interventions were among the most successful and efficient controls that helped to slow down the outbreak. As a result, Ebola could be controlled by finding and isolating symptomatic cases. That appears not to be the situation for COVID-19, due to the wide spectrum of symptoms and the evolving scientific investigations with regard to the pandemic.” The results of social distancing may not be seen immediately, he concluded, because of the time lag between transmission and individuals becoming infected and displaying symptoms. However, as his calculation demonstrates, measures implemented now can be expected to have substantial effects on future case numbers.

Considerable uncertainty surrounds COVID-19 – how long it will take before a vaccine is developed, the mortality rate and even how many cases there have been so far. But there is one thing of which we can be sure: social distancing works, according to mathematical modelling experts from UJ. The team, led by UJ’s Prof Farai Nyabadza, an advanced researcher in mathematical epidemiology, includes Dr Faraimunashe Chirove, Dr Maria Visaya and Mr Williams Chukwu. They crunched the numbers and quantified the level of social distancing that can reduce pass-on rates of COVID-19. Their mathematical modelling found that by relaxing social distancing, COVID-19 case numbers could rise to above 4 000 cases by the end of the lockdown. The model found that relaxing social distancing by 2% could result in a 23% rise in the number of cumulative cases; and increasing social distancing levels by 2% would reduce the number of cumulative cases by about 18%. Based on their model, increasing social distancing levels from 55% to 57% (ρ = 0.43), 59% (ρ = 0.41) and 61% (ρ = 0.39) would avert cumulative cases by about 18%, 32% and 53%, respectively, by the end of lockdown. Prof Nyabadza said that individuals migrating into South Africa had



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