#15,929
While there are a number of worrisome SARS-CoV-2 variants in play around the world - including P.1 in Brazil and B.1.617 in India - to date, the variant which has made the greatest inroads in the United States, and around the world, is the B.1.1.7 variant first identified in the UK.
Multiple studies have found B.1.1.7 to be roughly 70% more transmissible than the `wild type' COVID, and while there is still some debate over whether it produces more severe illness, and worse outcomes than `Classic COVID', we continue to see studies (see Eurosurveillance: Characteristics of SARS-CoV-2 VOCs B.1.1.7, B.1.351 or P.1: Data from 7 EU/EEA Countries) suggesting that it does.
In mid-January the CDC's MMWR predicted - when B.1.1.7 only made up a little over 1% of the total cases in the United States - that it would become the dominant strain by late spring (see MMWR: Emergence Of SARS-CoV-2 B.1.1.7 Lineage — United States, Dec 29, 2020–Jan 12, 2021).
By mid-March B.1.1.7 became the most reported strain (27%) in the United States, and two weeks later had jumped to a 44% share. As we can see in the CDC's latest data (as of 4/10), that number has jumped to more than 59%.
Although currently overshadowed by the meteoric rise of B.1.1.7, the P.1 and B.1.526 variants continue to rise as well - albeit at a considerably slower rate - and B.1.351 made modest gains in the the latest report. The other variants appear - for now at least - to be losing ground.
The overall drop in COVID cases, and fatalities, in the United States is likely due to the roll out, and substantial uptake, of three effective COVID vaccines.
While the B.1.1.7 variant is believed to be reasonably susceptible to the vaccine, some of the other variants are still question marks. Whether this will change the trajectory of some of these variants in the coming months is unknown right now.
While the above data represents the nation as a whole, there are substantial differences between regions and states (see interactive map below).
- The `California' variant(s) B.1427/B.1429 still dominates in California (39.2%) and Arizona (30.6 %), but not nearly as much as they did a few weeks ago, giving considerable ground up to B.1.1.7 in the latest report.
- The P.1 variant continues to rise in Illinois, Massachusetts, and Florida (roughly doubling to 14.1%, 7.3%, and 4.6% respectively) over the last report (3/27).
- B.1.1.7 has the greatest share of cases in Tennessee, Michigan, and Minnesota (72.3%, 69.6%, and 68.3% respectively)
The CDC's interactive Variant Proportions webpage provides a lot of interesting ways to look at and peruse the data, and is well worth a weekly visit.
While the juggernaut that is B.1.1.7 appears unstoppable right now, we've seen rapid - and often unexpected - changes to the field of variants around the world over the past few months.
A reminder that there are likely more surprises in store before this pandemic comes to an end.
