University of Cape Town Professor of Applied Mathematics Bruce Bassett speaks on possible scenarios for covid-19.
University of Cape Town Professor of Applied Mathematics Bruce Bassett speaks on possible scenarios for covid-19.

Is a third wave coming ?

By Tanya Waterworth Time of article published Mar 27, 2021

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As the threat of a possible third Covid wave looms, South African scientists have been working on possible scenarios for the country.

The government is considering stricter lockdown measures in an effort to prevent super-spreader events over the Easter weekend which could trigger a third wave.

Yesterday, the University of KwaZulu-Natal hosted a data breakfast on “Predictions for Covid in SA for 2021 and Beyond” with University of Cape Town Professor of Applied Mathematics Bruce Bassett, who is also head of cosmology and machine learning at the African Institute for Mathematical Sciences and leads the epidemiological modelling of Covid for SA Radio Astronomy Observatory as part of the national ventilator project.

Bassett said it was extremely difficult to make predictions with any accuracy and so research had focused on different possible scenarios.

He confirmed that the second wave had "plateaued and is in a holding pattern", but the key issues being looked at were whether the second wave ended because herd immunity had been reached or because of social dynamics (such as mask wearing, sanitising, social distancing, staying at home); whether the variant identified in South Africa would provide enough immunity from new variants of concern; and whether vaccines would provide immunity for such variants; as well as whether SA could be a source of new variants.

A variant of concern has a high level of transmissibility and danger in terms of causing serious illness and death.

Working on a worst-and-best-case scenario, Bassett said the worst case scenario would see 150 000 deaths annually in South Africa, potentially more if the virus became more lethal, and would include two or more waves a year for an estimated five years.

He said the HIV pandemic had a similar number in fatalities per year over 10 years.

The best case scenario would be no more waves, because herd immunity was reached (from infections and not social dynamics) and that the resulting immunity from infections would provide a robust protection against all new mutations. This protection would have to last until large scale vaccinations occur.

The intermediate scenario would be where one or two more waves would take place when herd immunity would be reached.

Bassett said that if the vaccination roll-out in South Africa continued at its current pace, it would take ten years before "a significant number" of the population was vaccinated.

He said the main concern was new variants (mutations), especially those which could affect the younger population. South Africa has a young population with only a very small percentage of people over the age of 65. If such a variant was more transmissible, that is, lots of infections at the same time, more ICU beds would be required which could result in more fatalities if hospital systems were overwhelmed.

With regard to the variant discovered in South Africa, Bassett said South African scientists had been "very fast" when it came to (genetic) sequencing data and had "quickly picked up this variant which could have emerged elsewhere".

Also of concern was that even asymptomatic or mild cases of Covid could result in heart damage, weakening the immune system and making a person more susceptible to re-infection should further waves take place.

The two top co-morbidities remain hypertension and diabetes, particularly in the 50-59 years age group, with HIV/TB sufferers also being susceptible (20-50 years age group).

In the Q&A session, it was highlighted that a co-ordinated global response was needed. Rich nations may be spending millions on vaccines, but new variants would still pose a threat and could provide an incentive for such nations to help vaccinate the rest of the world.

"Humans are trying to create vaccines, but the virus is looking to evade them. We need a world strategy to shut down the sources of variants," said Bassett.

Earlier this week, Health Minister Zweli Mkhize said that between April and June, 7 million Pfizer vaccines and 3 million Johnson & Johnson vaccines were expected to arrive in the country, adding that many countries were experiencing delays in delivery of vaccines because of the huge demand for supply.

The Independent on Saturday

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