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In a pattern the world has seen twice over the past year, a new version of the coronavirus is sweeping across the globe. Omicron’s BA.2 subvariant is already by far the world’s dominant form of the coronavirus, as recorded in the GISAID international repository of coronavirus genetic sequences analyzed by The Washington Post.
The worldwide chart of coronavirus variants below shows omicron’s dark red BA.2 subvariant as a small share during December and January, when the original version of omicron overtook the delta variant. BA.2 began squeezing out the original omicron in February and March as overall case counts were declining.
The GISAID sequences represent countries where genomic findings are publicly released, so some large countries are not included. It takes about a week for laboratories to identify virus variants, so this data is always time-lagged. Using the variant data, the Centers for Disease Control and Prevention estimated that omicron BA.2 was more than 70 percent of the covid cases in the United States.
The impact of the BA.2 subvariant is unclear. An uptick in coronavirus cases in the United Kingdom and parts of Europe is attributed to the new version of the virus. Some experts say a new wave could hit the United States amid relaxed safety protocols in the same way that delta hit last summer when many thought the coronavirus was finished.
Evidence is not clear on whether BA.2 causes more severe disease, but vaccine makers have said the protection extends to BA.2. Experts have said they believe infection from omicron provides some level of immunity against BA.2.
The charts below show the mix of coronavirus variants in a selection of countries that currently have high levels of omicron BA.2. To capture the latest trends, this map uses three-week periods, with the most recent ending last Saturday. In any country, the genomic sequences may be concentrated within a particular outbreak, or may miss some outbreaks, so it is not necessarily representative of the country as a whole.
Countries where omicron BA.2 is dominant
Sequencing is a process that maps out the genetic code of a particular virus that infected someone so it can be compared to other strains. It is a crucial tool to catch significant changes. If mutations change the virus enough, it becomes a new variant. Variants may have different behaviors that affect the transmissibility of the virus and make it evade the human immune system.
Public and private laboratories submit their sequencing results to the worldwide GISAID Initiative, a nonprofit partnership that broadcasts trends of viral diseases.
Only a very small sample of coronavirus cases are sequenced, and the process takes about a week. That makes the latest view always a bit out of date compared with daily coronavirus case counts that are setting records as omicron has spread.
Although the level of sequencing varies widely across the world and in the United States, many countries are generating sufficient public genome samples to reveal a trend.
Many countries have not provided sufficient timely samples to the public GISAID data to show the status of omicron’s spread. China and Russia have released very little. In some cases, there may not be technology or resources to do the genomic sequences. In other cases, it may be an issue of transparency.
U.S. variant trend
Sequencing within the United States varies widely. Nationwide, omicron BA.2 was 4 percent of coronavirus samples sequenced in late February, a far smaller share than worldwide.
The delta variant was first detected in India in late 2020 and then moved to Europe and the United Kingdom. It hit the United States in July just when coronavirus cases, hospitalizations and deaths were dwindling. Delta spread faster than the previous variants and was more likely than those variants to cause infections among vaccinated people. It quickly drove up a spike in cases that peaked in early September. Even as it waned, the low point in late October had six times as many cases as the low point before delta struck. In November, cases nationally began rising with another delta wave before omicron was spreading.
Omicron appeared at Thanksgiving and took over the world even faster than delta had. Omicron created even more cases and hospitalization.
This project will be updated.