MODELLING CONSORTIUM (PROJECTIONS)
COVID-19 MODELLING UPDATE: CONSIDERATIONS FOR A POTENTIAL THIRD WAVE (May 2021)
The South African COVID-19 Modelling Consortium was established to project the spread of the disease to support policy and planning in South Africa over the coming months. Due to the rapidly changing nature of the outbreak globally and in South Africa, the projections are updated regularly as new data become available. As such, projections should be interpreted with caution. Changes in testing policy, contact tracing, and hospitalisation criteria will all impact the cases detected as well as the number of hospital admissions and deaths that can be positively identified as associated with COVID-19.
Our updated projections show the following:
In the absence of a new variant:
- The peak of the 3rd wave is expected lower than the 2nd wave.
- The time from initial increase in transmission to the peak is on average 2-3 months.
- Across all age groups, hospital admissions are expected to be lower than in the 2nd wave.
- Hospital admissions at a provincial level are dependent on the
- seroprevalence after 2nd wave, age distribution, and prevalence of comorbidities
- individual responses to increasing case numbers that reduce the potential for transmission (e.g., by reducing contacts)
- strength of and adherence to
- Monitoring trends in cases is the best indicator of when a 3rd wave is likely to begin. The appendix has guidance on how to do this using the SACMC Epidemic Explorer.
- The emergence of a highly transmissible new variant may result in a 3rd wave of the same size as the 2nd wave or worse, especially if the variant provides an opportunity for immune escape.
- Delaying the start of the 3rd wave allows for more time for vaccination.
- The size of the third wave depends in large parts on the number of contacts people have
The most important finding is that in the absence of a new variant the projected size of a potential third wave is strongly dependent on the combined individual and nationally directed responses to increasing incidence. The report includes the projections from 5 scenarios according to the level and speed of the combined response by individuals and nationally directed restrictions. The “fast and strong” scenario is somewhat comparable with the response during the second wave. The other four scenarios provide projections should the response be more muted as a result of COVID-19 fatigue and/or a narrower policy space.
Under all scenarios the national peak daily hospital admissions for all age groups are projected to be lower than the second wave. With regards to the provincial projections, daily COVID-19 hospital admissions are projected to be lower for all provinces under all scenarios, with the exception of Gauteng. In Gauteng, 2 of the 5 scenarios projected the 3rd wave to be more severe compared to its second. In all three remaining scenarios, the 3rd wave was projected to be lower than the 2nd wave in Gauteng.