⚠️SUB-VARIANT SURGING—Omicron 2.0 is rising—the #BA2 sublineage of #Omicron has *tripled* in one week, dislodging the old Omicron from total dominance—BA2 now at 3.6% and climbing fast. Expect to be dominant by March. Omicron reinfections are possible. 🧵 covid.cdc.gov/covid-data-tra…
2) Omicron subvariant #BA2 now seems to be surging nationwide (pink), especially in the coastal regions of the Us the fastest. This means it’s not a fluke increase. US’s #BA2 trend will follow Europe’s rise for sure.
3) I’ve been worried about #BA2 for a while. In 3rd week of January, it was rising in Denmark— it’s now near total dominant in Denmark.
4) Multiple studies show the #BA2 subvariant is much faster transmission than old Omicron. Some say 30% some say ~90-120%, and some say 150% (1.5 time more).
5) Who said #BA2 is 1.5 times more contagious? Denmark’s CDC @SSI_dk said so—and they warned it was extending Denmark’s Omicron wave much longer. Same thing is going to happen in the US which is much much less vaccinated.
6) other tricky thing is that #Omicron #Ba2’s PCR looks like almost any other non-BA1 Omicron because the SGTF shortcut PCR won’t work on BA2. Thus it’s hard to tell apart BA2 from Delta variant without genome 🧬 sequencing.
7) Virus researcher & chief physician of 🇩🇰’s CDC @SSI_dk says you can get **reinfected with #BA2 sub-variant** of #Omicron after being infected with Omicron BA.1. ➡️ This is why we shouldn’t risk COVID or chase mass infection. nyheder.tv2.dk/2022-01-21-ny-…
8) It’s also surging in UK 🇬🇧 as well. #Ba2 d doubled in one week. It’s also surging in Netherlands and in Germany and elsewhere. It’s everywhere now- and quickly displacing the old Omicron 1.0.
9) How different is #Omicron BA2 from BA1? #BA2 has **17 additional mutations** that BA1 doesn’t have! There is also a BA3 but that one doesn’t have much difference beyond BA1 and BA2.
HT @WmHaseltine
10) Notably, “Each of BA1/2/3 variants is as different from one another as Alpha, Beta, Gamma, and Delta are from one another”! says @WmHaseltine
11) BA2 #Omicron is not a child-lineage of BA1 #Omicron. They are more like “cousins” that branched off earlier - hence they are much more different than parent-child versions of each other. This is also why reinfections could be higher.
12) If you still have any doubt in your mind about #BA2 being a 2.0 Omicron that will displace the old Omicron and cause a new surge— just look at how #BA2 (aka ‘Omicron 21L’ in the charts) is surging like mad across multiple countries (& this is just late Jan data!). Get ready.
13) 🇬🇧 data also shows a higher secondary attack rate in households for #BA2 versus the old BA1 Omicron. And the growth rate is indeed more than doubling per week. Exponential rise will beget exponential trouble - earlier Omicron immunity clearly isn’t slowing it much—not good.
14) Now the real bad news— two new studies say “immunity based on #Omicron-infection is weak for (another) Omicron reinfection” — if unvaccinated ⚠️
This means protection from your earlier Omicron may not be great if unvaccinated! 👀
15) Some relatively good news on #BA2 is that it seems to responds similarly to vaccines as BA1– but it responds well only to 3 vaccine shots if you get a booster. Without booster, the symptomatic efficacy is very poor —13% and that’s not even significantly different from 0.
16) Update on UK #BA2– it has doubled again and it’s now likely ~17% of all cases in England. And it has a much higher attack rate — altogether bad.
17) the reinfection risk of #Omicron is real. We need to take it seriously folks. Don’t feel like you’re invulnerable. That leads to blase attitude and risky behaviors.
18) Further—“results indicate that Omicron infection enhances preexisting immunity elicited by vaccines, ➡️but on its own **may NOT induce broad, cross-neutralizing humoral immunity in unvaccinated** individuals.” ⚠️
Don’t risk #Omicron BA2 if unvaxxed! medrxiv.org/content/10.110…
19) It now seems the @WHO is getting very concerned about #BA2 variant outcompeting and displacing old #Omicron. @mvankerkhove is now warning about likely looming surge. We must be vigilant.
HT @Cleavon_MD.
20) It is now 100% clear that the @WHO needs to declare #Ba2 a high risk “variant of concern”. Dear @mvankerkhove @doctorsoumya @DrTedros @gabbystern @DrMikeRyan — please make it so. VOC declaration of BA2 now ASAP!
See 🧵 below.
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