Thread by @miamalan

[Thread]. 1. What will influence the severity of a 4th #COVID19 wave?

New variants.

We don't know if there will be a new variant, but we do know that each previous SA wave was driven by a different variant:

Wave 1: Original form of SARS-CoV-2
Wave 2: Beta
Wave 3: Delta

2. What can we not for certain say about a 4th #COVID wave?

* We cannot predict if + when a new variant will emerge + what it will look like
* SA's modellers = decided to use a variant that can escape immunity (make jabs work less well) 4 their modelling 2 look @ a 4th wave

3. What else can influence what a 4th #COVID19 wave looks like?

Vaccination coverage.

Where are we at?
* About 16 million adults, or 40% of adults, have received at least one dose of vaccine
* 34% of adults = fully vaccinated

.

4. Where is SA at with #COVID19 infections?
1. 60-70% of SAs have likely had #COVID (this is what modellers estimate using different data sources)
2. This estimated infection rate is much higher than in the Northern Hemisphere

5. Modellers made the following assumptions for their estimations:
1. 70% of adults (and 75% of 60+) would have received one jab by the end of March
2. Vaccines = not 100% effective
3. Vaccine effectiveness @ #COVID infection wanes after 6 mnths, but no waning 4 hospitalisation

6. Modellers considered 4 scenarios:
1. Changes in behaviour in terms of mask wearing, social distancing, etc. (Think: Dec holidays; people = tired of measures)
2. A variant that reduces vaccine effectiveness by 25% emerges

They looked @ different combinations of these things.

7. Scenario 1 a and b:

a. If people slow down with mask wearing, etc in Nov (no new variant):
- Peaks of hospital admission = smaller than in previous waves

b. If they slow down in Jan (no new variant):
- Hospitalisations = later, but in nrs = about the same as in "a"

8. If we vaccinate a higher % of people of 60+ than in younger groups, there will be far fewer hospital admissions (60+ = most likely to fall seriously ill).

9. Scenario 2: People return to the way they behaved before #COVID19 (no masks, etc) despite increased infections (unlikely scenario) amidst a new variant that can escape immunity emerging.

- Admissions = higher than in scenario 1, but lower than in Wave 2 and 3, except for EC

10. Scenario 3: A new variant emerges that makes jabs 25% less effective, but people don't slow down with protective measures at all (unlikely scenario)

- Slow increase in admissions, but with higher peaks than in scenario 1

11. Scenario 4 (most realistic): New variant, people slow down with protective measures
1. Admission peaks lower than in Wave 2 + 3 (NC/FS = hard to model)
2. That doesn't mean hospitals won't run out of capacity as most of their resources = no longer allocated to just #Covid19

12. If we have a high (75%) vaccination rate among 60+ then hospital admissions for Wave 4's scenario 4 (new variant, slow down in protective measures) will be reduced significantly.

13. How many admissions did we have in previous waves?

Wave 1: 103,400
Wave 2: 149,300
Wave 3: 177,500

How many admissions will we have with scenario 4 for Wave 4?
About half of those in Wave 2 and 3

14. What will #COVID19 infections look like? In all scenarios they're still high, but the difference is that hospital admissions = lower because vaccines protect you against falling seriously ill with #COVID.

15: The crux?

Modelling predicts, with all 4 scenarios, that Wave 4 will generally have fewer people falling seriously ill with #COVID19 (so fewer hospital admissions) because of vaccination. So still many infections, but fewer hospital admissions and deaths.

16. Data source = @nicd_sa webinar this afternoon: we.tl/t-H7JvoK1Jyk

Full report here: bit.ly/3FlEHB0