Severity: Delta caused more severe disease than other variants in people who weren’t vaccinated. In the fall of 2021, there were surges even in the most vaccinated states, prompting experts to urge people to get their booster shots. In the U.S., in June 2021, after a steady decline in COVID-19 cases and hospitalizations, the arrival of Delta coincided with a rapid reversal of that trend. How contagious is it? It’s estimated that Delta caused more than twice as many infections as previous variants-in Connecticut, it was estimated to have been 80 to 90% more transmissible than the Alpha variant. Deltaĭelta (B.1.617.2) was first identified in India in late 2020 it soon spread throughout the world, becoming what was the predominant version of the coronavirus-until Omicron took its place in mid-December of 2021. ![]() Currently, the CDC says the updated vaccine is expected to be effective at reducing severe disease and hospitalization from the two recent subvariants. Scientists are evaluating the effectiveness of a new fall 2023 updated COVID-19 booster against EG.5 and BA.2.86, according to the CDC. ![]() But it has also been noted that surges in cases may lead to significant increases in hospitalizations and deaths, as they did during the variant’s spread at the beginning of 2022, when the estimated death rates went as high or higher than they were at the time of the Delta variant surge in the previous autumn.Ĭan vaccination prevent it? The CDC says that while breakthrough infections in vaccinated people are expected, staying up to date with vaccinations is the best protection against Omicron. Data has suggested that the original Omicron strain was less severe, in general, than previous variants, according to the CDC. Severity: Scientists are still working to learn more about whether the current Omicron strains cause more severe disease than their predecessors. One explanation was that more than 30 of Omicron’s mutations are on the virus’s spike protein, the part that attaches to human cells, and several of those are believed to increase the probability of infection. The original strain of Omicron was more transmissible than Delta was. How contagious is it? Omicron’s subvariants are considered to be especially efficient spreaders of the disease. In 2023, a new Omicron strain called EG.5 (nicknamed “Eris”) is the dominant strain in the U.S., and experts are monitoring another new strain called BA.2.86 (nicknamed “Pirola”). In 2022, it had spawned a number of subvariants. By December of that year, Omicron was causing daily case numbers in the U.S. Omicron was first identified in Botswana and South Africa in late November 2021, and cases quickly began to surface and multiply in other countries. ![]() While the original Omicron strain (BA.1) is no longer circulating, Omicron subvariants are now driving most of the country’s SARS-CoV-2 infections. Omicron and its subvariants have ranked as the predominant SARS-CoV-2 strains in the U.S. The World Health Organization (WHO) names new coronavirus variants using the letters of the Greek alphabet, starting with the Alpha variant, which emerged in 2020.īelow is a list of-and information about-some of the variants that have been top-of-mind. This is especially true if a new variant is more aggressive, highly transmissible, vaccine-resistant, able to cause more severe disease-or all of the above, compared with the original strain of the virus. ![]() Since the beginning of the pandemic, we’ve seen a number of prominent variants, including Alpha, Beta, Delta, and Omicron.Īlthough new variants are an expected part of the evolution of viruses, monitoring each one that surfaces is essential in ensuring we-in the U.S. One thing we know for sure about SARS-CoV-2, the virus that causes COVID-19, is that it is changing constantly. Because information about COVID-19 changes rapidly, we encourage you to visit the websites of the Centers for Disease Control & Prevention (CDC), World Health Organization (WHO), and your state and local government for the latest information. Note: Information in this article was accurate at the time of original publication.
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