Besides Delta, the other major story here is B.1.621. It's now firmly the second most frequent variant in CT (~8%), and has so far been able to maintain its ground against the expansion of Delta. Something that Alpha, Gamma, and everything else couldn't do. (3/9)
B.1.621 (first detected in Colombia) does not yet have a WHO greek letter, but IMO, its just a matter of time. It has several key spike mutations - E484K, N501Y, and P681H - and is now being found at high frequencies in other states. (4/9)
While we were able to fix our B.1.621 submission issue with GISAID, its still an issue for other groups. Almost certainly B.1.621 is under-reported in some regions in this CDC figure (not of the fault of the CDC). The GISAID issue means there there are still back-logs. (5/9)
In CT, the reported cases are ~12/100K population/day, but Covidestim reports a much higher estimated infection rate at ~72/100K population/day. This is similar to our neighbors, but much lower than states in the south (e.g. FL = 335, LA = 552). (6/9)
Link to covidestim to look at the numbers yourself (7/9) covidestim.org
Our variant-specific RT estimates show that most of the rise in cases is coming from Delta (Rt = 1.59) and B.1.621 (Rt = 1.34; shown as Non-VOC/VOI), with the rest not currently playing a critical role. (8/9)
I'd like to once again thank my entire team. As cases rise, so does our work. Its a very tough time a year to be busy again, and we all just want a long break. But as always, they step up to keep the surveillance system running. I owe them lots of 🍻(9/9)
It's based on a design led by @Scalene & @pathogenomenick originally for Zika virus that was adapted for SARS-CoV-2 ("ARTIC protocol") and used by labs around the world.
Our goal was for this to be plug n' play with current SARS-CoV-2 protocols. (2/8) nature.com/articles/nprot…
The primers were designed using PrimalScheme using a pre-outbreak A.1 clade reference genome (GenBank accession: MT903345).
The scheme comprises a total of 163 primer pairs with an amplicon length ranging between 1597 and 2497 bp (average length of 1977 bp). (3/8)
Using a logistic regression of the daily frequencies, we predict that as of today (July-14), BA.5 is probably 80-90% in Connecticut.
BA.4 is still 📈 as it outcompetes BA.2, but will probably start to 📉 in frequency soon after BA.2 is gone. (2/8)
We created a new dashboard to report variant sequencing data in Connecticut. You can still access it through our main website by clicking on the "Read the latest Connecticut report" link. (3/8)
Omicron BA.2.12.1 is still 📈 in Connecticut as it is across most of the US. Fitting the % of sequenced cases to a logistic growth curve, we estimate that BA.2.12.1:
1⃣ is ~80% frequency today (May019)
2⃣ surpassed 50% in early May
3⃣ may reach 95% in early/mid June
(2/13)
From the same logistic growth curve, we also estimate that BA.2.12.1 is:
➡️ ~24% more transmissible than background (mostly other BA.2 lineages)
➡️ doubling in proportion every ~12 days
(3/13)
Based on our TaqPath PCR data (S-gene detected), we estimate that:
➡️ BA.2 is >50% in Southern Connecticut
➡️ At this rate - BA.2 will be 95% by early April
➡️ BA.2 doubling rate = 7.8 days (BA.1 in December = 3-4 days)
➡️ BA.2 ~43% more transmissible than BA.1/.1
(2/7)
Over the past 4 weeks, all of the sequenced S-gene positive samples have been Omicron BA.2 and not Delta. So we trust the 👆 PCR results reflecting the rise in BA.2. (3/7)
Here are comparative results between 10 TaqPath S-gene detected samples tested by YNHH and with our validated VOC PCR assay. Most with our assay were actually SGTF, and looking at the YNHH results, the S-gene CTs for those were 5-7 higher than N/ORF. (5/16)
We are looking into these low level spike amplification samples that should be SGTF to see if this is a lab/TaqPath assay artifact or if there is something about these BA.1 sequences. So far doesn't seem to be sequence-related. Will report (6/16)
Our initial SGTF case definition – ORF/N <30 CT, S “not detected” - was conservative to not over-call BA.1.
We updated it yesterday to include S-gene 5 CTs higher than ORF/N, and compared the results. (7/16)