3/6 We predicted that B.1.1.7 would become dominant in CT in our recent paper led by @tdalpert, @AndersonBrito_, & co. However, we thought that this would have happened earlier in March. The slowdown of B.1.1.7 was likely due to the rapid rise of B.1.526.
4/6 This figure by @MaryPetrone10 shows how B.1.1.7 and B.1.526 (including B.1.526.1 & B.1.526.2) are increasing at similar rates, displacing most other lineages in CT. Based on our most recent sequencing data, these together make up ~80% of the cases in CT.
5/6 The co-rise of B.1.1.7 and B.1.526 is leaving little room for other variants - like B.1.351 & P.1 - to emerge and spread. Perhaps this is a good thing, as P.1 + Brazil is a terrible situation, but that really depends on the impacts that B.1.526 will have on public health.
6/6 This week I'd like to highlight the work by @aewatkins6 who manages a lot of our PCR and lineage reports data. She also has helped to lead many of our NBA/NFL projects prior to this. Here she is with @XtinaHarden and our first delivery of saliva samples from the NBA last June
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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)