2/8 Last week we saw a dip in the probably B.1.1.7 cases determined by TaqPath SGTF results. I showed how the sequencing tracked with the SGTF data, and that the dip was probably a blip...
3/8 That "blip" was confirmed: B.1.1.7 📈 this week in both the sequencing and TaqPath SGTF data (shown 👇). While we expect B.1.1.7 to continue this trend until it dominates (like in the UK), the good news is that we are seeing a reduction in both B.1.1.7 and non-B.1.1.7 cases.
4/8 This week we sequenced 2 B.1.1.7 samples + the E484K mutation. They are unrelated to each other, likely representing independent emergences/introductions into CT. So far this is not too alarming given their low frequencies, but something that we keep an eye on.
5/8 This week the CDC updated their VOI list to include B.1.526.1, but not B.1.526.2. Their likely rationale is that B.1.526.1 has the L542R mutation, which the CDC recently classified as a "Substitution of Therapeutic Concern", along with E484K.
6/8 Before the update we were lumping B.1.526 + B.1.526.1 + B.1.526.2 as "B.1.526", which is still reflected as such in our main frequency plot (we'll update this for next week).
👇 is a breakdown of the B.1.526 lineages showing their decline in recent weeks.
7/8 This week we added a new section on "SARS-CoV-2 mutations of interest". The figure shows the temporal frequencies of Spike E484K on all lineages, and you can find similar plots for several other mutations by following the links.
8/8 This week I'd like to recognize 🌟 PhD student @MaryPetrone10 for establishing the Illumina COVIDseq protocol in our lab that significantly expanded our capacity. She's also leading several projects, e.g. comparing the 💪 of B.1.1.7 vs B.1.526 in CT.
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)