Thread by @DrEricDing

⚠️TWO DIFFERENT #COVID19 PANDEMICS—Many think with cases dropping that pandemic is nearly over. But truth is, there are now 2 different #SARSCoV2 pandemics diverging—old strain is waning, while the more contagious #B117 strain is dominating. We will be soon slammed very hard. 🧵

2) Here is what is really going to happen... most countries are having a gentle case decline with R(e) currently around 0.9. But this is deceiving. The #B117 is still relatively rare so far, so the R is being influenced mostly by the old common variant. But not for long...

3) Here is what is going to happen... currently R is ~0.9 in many places, but with the more infectious #B117, the R will jump 50% approximately. And it is inevitable (all CDC and Danish models say this) that B117 will take over as the reigning dominant variant soon...

4) and when that happens, what worked before to keep the pandemic contained at R of 0.9 will no longer work. Here is the model for Alberta, 🇨🇦 by @GosiaGasperoPhD. The B117 dotted red line will soon dominate and drive a new surge in latter half of March and April.

5) And Denmark 🇩🇰 CDC has found the same thing. I GQR works now for keeping R around 0.9 or even 0.8, will absolutely not work anymore once #B117 variant takes over. Forget about it. We will be hit hard. But there is a way—if we suppress R to 0.7 or less.
covid19.ssi.dk/-/media/cdn/fi…

6) The solution to defeating the #B117 is to chase a #ZeroCovid approach and slam the R even lower to below 0.7.... but optimally 0.6 or less. So that even when the #B117 arises, it will keep R under 1 (0.6*1.5=0.9). And by keeping R at 0.6 now—we will have buffer room for B117.

7) And again Denmark 🇩🇰 CDC agrees with that assessment. Their model for R of 0.8 shows it is insufficient to defeat #B117. But its model for R 0.7 shows it can be enough.
covid19.ssi.dk/-/media/cdn/fi…

8) The problem is that of the declining states, only 1 state is under R 0.7... which is Wyoming (figure below sorted from lowest to highest R). Every other state’s R is over 0.7. Thus while they would yield decreases now—they won’t once #B117 takes over.
epiforecasts.io/covid/posts/na…

9) Meanwhile, the replacement thing is happening in England. #B117 is dominating while old common #SARSCoV2 is all but nearly gone. Total cases dropping only because of tight UK lockdown. But can UK sustain & not let up on gas pedal before politics caves to reopen too soon?

10) Here is another @GosiaGasperoPhD model of the same thing. Keeping the R at 0.8 level is not enough to stop the spread once #B117 takes over.

11) Denmark 🇩🇰 CDC @SSI_dk has been warning about this for over a month. The world hasn’t been listening. Aggressive mitigation for keeping R under 0.7 now is the only way.

https://twitter.com/drericding/status/1346899021621813249

12) Let’s slam this home. suppose we have 1000 cases/day now... with an R=0.86 we could reduce it to 500/day in 2 weeks.

➡️But w/ added contagiousness of B117 variant that has ~60% higher R, in 2 weeks, 3000 new cases/day instead.

➡️6x difference in 2 wks

HT @GosiaGasperoPhD

13) The problem is that to get R low enough, what used to work won’t work anymore. When we previously could afford to open schools, it may be that when B117 becomes dominant, we might lose that buffer to keep R<0.7.

https://twitter.com/drericding/status/1346620196736413696

14) Denmark CDC is becoming more right — contagious #B117 variant is continuing to solidify itself as 12.1% of sequenced #SARSCoV2 samples. 70% increase per week!

2.4%

4.0%

7.4%

12.1%

15) Denmark officials, despite their lockdown induced case drop, are really panicking. Seriously— read the WaPo article or this thread 🧵 below. They express that without the 100% sequencing, they would have been lulled into complacency.

https://twitter.com/drericding/status/1353297240610189315

16) “Without this variant, we would be in really good shape,” said Camilla Holten Moller, co-leader of the @SSI_dk group modeling the spread of the virus.

“If you just look at the reproduction number, you just wouldn’t see that it was in growth underneath at all,”

17) The good news so far is that all the vaccines tested so far perform decently against the main #B117 variants, but maybe less so against the 🇿🇦 #B1352 and 🇧🇷#P1 variants. Pfizer, Moderna, etc mostly good for B117. See thread 🧵 below to catch up.

https://twitter.com/DrEricDing/status/1353706396282474499

18) So here comes the “but”... there is a new subtype of #B117 emerging... a mutated sublineage of regular main #B117 that had acquired the troublesome E484K mutation. This is the bad mutation that 🇿🇦 CDC & other studies helps B1351 evade antibodies.

https://twitter.com/drericding/status/1356365178330378251

19) So what do we know about the #B117+E484K combo sublineage? Not much except this preprint study showing it is might be more resistant to antibody neutralization (more antibodies needed in lab study to neutralize the pseudovirus) than the common strain and the regular B117.

20) This #B117+E484K isn’t for sure resistant to vaccine. We don’t know yet. And we don’t know if it will still be more contagious like the main B117 is, but we should assume it is—& take precautions that it might be the double combo of more contagious & maybe antibody resistant.

21) could #B117+E484K be a fluke? Maybe. But it emerged recently in UK twice—independently arising in Wales, and arising in England. Just like in 🇧🇷 and 🇿🇦—so 4 times means convergent evolution is real. And convergent evolution is usually always greater survival fitness.

22) The other way to win is with mass vaccination like in Israel 🇮🇱 that has already vaccinated 50 shot per 100 people in the elderly. Hence now look how fast the cases, hospitalizations are diverging for those age 60+ vs 59 or under. That is the effect of **mass** vaccinations.

23) Actually, Israel 🇮🇱 has now reached 60 vaccination shots per 100 people: 4x UK 🇬🇧 and 6x the 🇺🇸. Rest of EU is much much lower.

24) Another alarming datapoint: 10% of the village of Corzano 🇮🇹 has the #B117 variant—10% of all residents!!! tg24.sky.it/milano/2021/02…

25) Moreover, of the 10% of the infected 🇮🇹 village with #B117 UK variant, 60% of cases are kids from kindergarten and primary school, while other 40% are their parents. Schools in the village have closed now.

https://twitter.com/DrEricDing/status/1357599530296958982

26) BOTTOMLINE: unless we can mass vaccinate quickly like Israel (which is still not 1/3 of the way done), we must continue to mitigate with *premium* masks preferably and with airborne virus precautions to ventilate.

💡No virus = No mutation.

#ZeroCovid #COVID19 #COVIDzero

27) here is where you can find the R(e) or R(t) in your US state. epiforecasts.io/covid/posts/na…

28) Please switch to premium masks if you can. KN95, KF94, FFP2, etc.... the new variant is just too contagious not to take extra precautions.

https://twitter.com/DrEricDing/status/1353186978519539712

29) If you’re skeptical, you don’t have to take my word alone. Read this article in Science magazine by @kakape, he essentially outlines the same thing as I have with the ominous pandemic future of #B117. I trust my colleagues at Denmark 🇩🇰 @SSI_dk a lot. sciencemag.org/news/2021/02/d…

30) Also why aren’t we aware of that much #B117 in other countries besides Denmark and UK? Well because most countries sequence almost nothing (panel B is a log scale - so the drop off is much much worse as you go down), and also very slow in sequencing even when they do.

31) Based on the limited #SARSCoV2 genomic sequencing that we do have... here is how different mutations are growing in each country so far (data slightly older by 1.5 weeks). Pink is the N501 mutation (seen in a few, but #B117 is the main variant with it)
covariants.org/per-country

32) Is #B117 a VARIANT or new STRAIN? People are now use them interchangeably. Let’s end the confusion. Experts say a variant is crowned a new strain when:

📌Becomes dominant (B117 🇬🇧)

📌More transmissible (B117), deadlier, or modifies immunity. #COVID19
latimes.com/science/story/…

33) To be honest, I’m equally worried about the #B1351 variant from South Africa that may cause reinfection resurgence worldwide.... stunning finding...

https://twitter.com/drericding/status/1358065355785134083