2/8 We didn't see an increase in the % of B.1.1.7 from the sequencing data last week, and the TaqPAth SGTF data also suggests that the expansion of B.1.1.7 *might* be slowing down in CT.
While this is good news, I think that it points to something else...
3/8 That something else is B.1.526.
It made up 32% of the sequenced cases analyzed this week, a 9% increase from the week before.
Its proportion is higher in Fairfield county, which is close to NY - where B.1.526 is currently dominating.
Data 👇 since 2/1
4/8 What does the rise in B.1.526 mean?
Not quite sure yet. This lineage is complex. Some have the Spike E484K mutation (left), while others have the S477N mutation (right). We don't quite have a handle on their impact on vaccines and/or disease in the context of this lineage
5/8 There are now at least 8 lineages in CT with the E484K mutation, which was found on ~20% of the samples sequenced last week.
Top to bottom order on tree 👇:
- B.1.526
- B.1.314
- B.1.351
- B.1.525
- B.1.1.7
- P.1
- R.1
- R.2
6/8 Even though the cases are low, we are starting to see evidence for local transmission of both B.1.351 (left) and P.1 (right) in CT.
Not sure how much room is for these variants to take hold with the growing dominance of B.1.1.7 and B.1.526. Will be very important to watch.
7/8 This week I'd like to highlight the work by @IsabelOtt and @mallerybreban - our amazing sequencing duo! They sequence 188 samples per week, and generating fantastic data. I mean, it doesn't get a whole lot better than this 😍
COVIDseq + NovaSeq = win
8/8 I'd also like to highlight the work by our partners @jacksonlab - led by Mark Adams 👏
They've been increasing their random sequencing and are also detecting the rapid expansion of B.1.526 (purple).
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)