Thread by @DrEricDing

📍5th WAVE BEGINNING in SA—cases are surging again in South Africa 🇿🇦, which in the past week is seeing cases tripling, positivity rates also up, and hospitalization rising. The surge has SA facing a possible fifth wave, linked to #BA4 & #BA5 subvariants. nytimes.com/2022/05/02/wor…

2) “What we are seeing now, or at least maybe the first signs, is not completely new variants emerging, but current variants are starting to create lineages of themselves,” Dr. de Oliveira said. Since initial identification last November, Omicron has produced several subvariants.

3) “Some scientists are trying to understand what the BA.4 and BA.5 spike in South Africa, which is concentrated mainly in the Gauteng, Western Cape and KwaZulu-Natal provinces, says about immunity from previous Omicron infections.

4) The highly contagious Omicron variant first appeared in South Africa late last year, then quickly spread globally.
In South Africa, researchers estimate about 90 percent of the population has some immunity, in part from inoculation but largely because of previous infection.

5) Yet immunity from infection typically begins to wane at around three months. It’s natural to see re-infection at this stage, particularly given people’s changing behaviors, like less mask-wearing and traveling more, said @AliHMokdad , an epidemiologist

6) Emerging data show that in unvaccinated people, **BA.4 and BA.5 evades natural defenses produced from an infection with the original Omicron variant** BA.1, Dr. de Oliveira said. 👀

“That is the reason why it is starting to fuel a wave in South Africa,” Dr. de Oliveira said

7) What’s the data look like on weaker protection against #BA4 and #BA5 if you had previous BA1 original #Omicron? new results from @sigallab show that “previous infections with BA.1 will not be sufficient to prevent a second infection with BA.4 and BA.5.” (lab neutralization)

8) where are things with the variant dominance? #BA4 and #BA5 poised to take over. Old #BA1 is virtually extinct in SA now.

9) “We’re at an awkward global moment where the past can’t really predict the future,” said Dr. Kavita Patel @kavitapmd, a primary care physician who led the pandemic preparedness response for the H1N1 swine flu virus during the Obama administration.

10) The familiar patterns — a wave in one country means another wave elsewhere —no longer necessarily work like clockwork, @kavitapmd said. But monitoring situations and data coming out of countries like South Africa offers reliable signals to understanding the virus’s evolution.

11) Currently, another Omicron subvariant, BA.2, is dominant in the United States, with BA.2.12.1 gaining speed as well although public health officials have identified BA.4 and BA.5 circulating at low levels.

#Ba2121 has been surging for weeks in Us.

https://twitter.com/drericding/status/1516513505696010243

12) Whatever the dominant variant, “the lesson here is **stopping transmission** is the most important,” said Dr. Eric Feigl-Ding, an epidemiologist who is the chief of the Covid-19 task force at the World Health Network @TheWHN.

nytimes.com/2022/05/02/wor…

13) many who follow me know that I’ve been warning about #BA4 and #BA5 for many many weeks. People tried to dismiss the rise then. But now the folks who minimized and dismissed these variants are no longer dismissive and now worried too.

https://twitter.com/DrEricDing/status/1513641429108760580

14) shit— all three of the new troublesome subvariants #BA2121 and #BA4 and #BA5 now found to “escape antibodies elicited by #Omicron infection” (of the original #Ba1 old omicron). 👀

https://twitter.com/gab_h_r/status/1521201654334464004