Thread by @miamalan

🧵1. Is SA in a 5th #COVID19 wave?
@ProfAbdoolKarim: It’s too early to tell. We don’t have reliable data 2 compare infections of the last 7 days with the previous 7 days. Why? SA = 2 holidays in the past week, so testing nrs = down + can’t reliably be compared 2 the previous wk.

2. Why do we need to compare data of the last 7 days with the previous 7 days?

- For a 5th wave the 7-day moving average would have doubled every 2-3 days (so we would have had 10,000+ cases by now)
- But we’ve seen only a 52% increase: from 3,097 (April 24) to 4,693 (May 1)

3. Does the lower-than-expected increase for a new wave mean we’re not in a 5th #COVID19 wave?

Not necessarily — it could just be that testing numbers are down because of the 2 public holidays in the past week (far fewer people go to test on public holidays).

4. But increases in #COVID19 cases slowed down this past week - in all provinces - and are not following a rocket-like upward trajectory like we’d expect in a 5th wave.

5. What is driving the uptick in #COVID19 infections? Two new forms of #Omicron, BA.4 and BA.5. So are BA.4/5 capable of driving a 5th wave? @sigallab, who grew BA.4/5 in his lab, says yes: bit.ly/39zH0Gb

6. Can BA.4/5 outsmart antibodies we get from vax, infection with BA.1 (original form of #Omicron) or both? To some extent, but not entirely. The extent that these subvariants can do this depends on your vax status. How? (next tweet)
@sigallab's preprint: bit.ly/3w3V825

7. @sigallab grew BA 4+5 and then tested the serum of
- unvaccinated people infected with BA.1
- vaccinated people (#Pfizer or #JnJ) who got infected with BA.1 (this is called breakthrough infections)
to see if BA.1 immunity neutralised BA.4/5 viruses.

8. @sigallab found:
- Unvaccinated people (previously infected with BA.1): 7.6-fold (BA.4) and 7.5-fold (BA.5) drop
- Vaccinated people (previously with BA.1): 3.2-fold (BA.4) and 2.6-fold (BA.5) drop

in neutralisation of the #COVID19 (BA.4/5) virus.

9. What does the above data tell us?
Vaccinated people previously infected with BA.1 who were exposed to BA.4/5 had neutralisation levels 5-fold higher than unvaccinated people previously infected with BA.1.

https://twitter.com/sigallab/status/1520097456779845634

10. @ProfAbdoolKarim says we're therefore likely to see more unvaccinated people with previous BA.1 infection than vaccinated people with breakthrough BA.1 infections to get re-infected with BA.4/5 (e.g kids below 12 who don't yet qualify for vaccination).

11. Will we see a 5th wave caused by BA.5/4. @ProfAbdoolKarim: It’s too early to tell, but indications = a short-lived uptick = more likely than a wave. But we 1st need #COVID case data from a holiday-free week, so we need 2 wait 4 one more week for a clear-cut answer.