2/9 Last week when we reported that Delta was only 2.3% I said: "This is probably more of a reflection of noisy data when trying estimate frequencies from a small number of cases", and followed that up with an expectation that we will see Delta π.
3/9 This week we are seeing the expected π in Delta (B.1.617.2), but the caveat still remains that our estimates are noisy because of the low numbers of sequenced cases (a product of the low numbers of cases, which is a good problem to have π)
4/9 To improve our weekly estimates, we are now also including recently sequenced data from the CDC (typically samples tested by Quest Diagnostics).
5/9 Interestingly, the frequency of "Other variants" is going π for the first time since our variant surveillance began in early 2021 (see 2x π). We are finding that this is being driven by lineage B.1.621.
6/9 While B.1.621 is not yet listed as a variant of concern/interest, but it has both the E484K and N501Y mutations found in Beta (B.1.351) and Gamma (P.1) that are known to decrease the efficacy of some vaccines. (source = outbreak.info)
7/9 B.1.621 represents <1% of the cases in the US and has not been detected in many places of the world.
**However**, B.1.621 represents ~15% of the sequenced cases in Colombia, and is recently trending π in association with π cases. (source = outbreak.info)
8/9 This is not to say that B.1.621 will become a concern here, I'm primarily highlighting what our surveillance system is intended to do: detect emerging lineages so that we can understand its epidemiology and inform public health. I'll provide updates as we learn more.
9/9 I'd like to thank the @CDC_AMD program, especially @dmaccannell, for not only providing financial support for sequencing, but also for π their sequencing efforts to enhance our surveillance program in Connecticut. We greatly appreciate their commitment to open data sharingπͺ
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2/8 In Connecticut, the % of sequenced cases that are the Delta variant (B.1.617.2) decreased in recent weeks. This is probably more of a reflection of noisy data when trying estimate frequencies from a small number of cases vs an actual decline in delta.
3/8 Looking at our neighbors in Massachusetts and New York, delta is 10-20%, so we in Connecticut are probably pretty close to that. My guess is that we'll see a π in delta in the coming weeks to reflect the trends of our neighbors.
2/7 Gamma (P.1) and Delta (B.1.617.2) continue rising in Connecticut, while Alpha (B.1.1.7) and others decline, following national trends (see next tweet).
3/7 Data from outbreak.info shows that in the US πΊπΈ, Delta (B.1.617.2) is π exponentially, while Alpha (B.1.1.7) is on the π. Despite this, COVID-19 cases are still dropping (for now).
2/6 We now have 8 cases of B.1.617.2 (5 shown in the π²) and 2 of B.1.617.1. To my knowledge, none of these are associated with βοΈ. Our phylo π² shows that there are at least 4 independent transmission chains of these viruses, spanning at least 3 counties. Definately one to π
3/6 The π in B.1.1.7 shown in tweet 1 is probably a combination of noisy data with few cases and the emergence of other lineages. The figure π 1 is from TaqPath SGTF data, which is a week ahead of the sequencing shown π, where we don't yet see the sudden π.
2/5 The second case of B.1.617.2 was from the same county as the first case (Fairfield), but they are unrelated (see tree π). Neither cases are known to be linked to international travel.
3/5 B.1.1.7 is still π frequency not because the lineage is rapidly expanding, but because it is dying out slower than the non-B.1.1.7 lineages. So the total number of B.1.1.7 cases π by 87% since late March.
2/7 B.1.617 first reported in India comes in 4 different flavors primarily defined by their spike gene mutations. While the CDC currently recognizes all 4 as VOIs, the B.1.617.2 lineage that we detected importantly does not have the E484Q mutation.
3/7 The B.1.617.2 case was not associated with travel, suggesting that there is some level of local transmission. Though the presence of other highly transmissible variants in CT - like B.1.1.7 - may limit its ability to become established.
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 π this week in both the sequencing and TaqPath SGTF data (shown π). 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.