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Government responses. Extinction. See also. Notes. References. External links. SARS-CoV-2 Delta variant. For lineage B.1.617.1, see SARS-CoV-2 Kappa variant. This article is about a variant of the virus that causes COVID-19. It is not to be confused with the Deltacoronavirus grouping of coronavirus species that affects birds and non-human mammals.
Trend in % COVID-19 Deaths. -14.3% in most recent week. Mar 23, 2024 May 11, 2024. CDC | Test Positivity data through: May 11, 2024; Emergency Department Visit data through: May 11, 2024; Hospitalization data through: April 27, 2024; Death data through: May 11, 2024. Posted: May 20, 2024 3:15 PM ET. View Trends.
Dec 20, 2021 · We analyzed Covid-19 breakthrough case and death rates among cohorts of fully vaccinated persons 12 years of age and older defined based on month of completing the primary Covid-19 vaccine series...
Jul 31, 2021 · The highly contagious Delta variant is now responsible for almost all new Covid-19 cases in the United States, and cases are rising rapidly.
- Overview
- Discussion
- References
On January 21, 2022, this report was posted online as an MMWR Early Release.
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COVID-19 vaccines reduced risks for SARS-CoV-2 infection and COVID-19–associated death during periods of Delta variant predominance and infection risk during Omicron variant emergence. Because of reporting lags, the influence of the Omicron variant on COVID-19–associated deaths by vaccination status in December could not be evaluated. Substantial case rate increases were recorded among unvaccinated and vaccinated persons when Omicron became the predominant variant in December, resulting in decreased IRRs and declining crude VE estimates (7). IRRs and VE were higher among persons who were fully vaccinated and had received a booster dose than among fully vaccinated persons who had not received a booster dose for cases and deaths during the period of Delta predominance and for cases during the period of Omicron emergence in December. The added benefits of booster doses were especially prominent among persons aged 50–64 and ≥65 years.
The findings in this report are subject to at least five limitations. First, booster doses could not be distinguished from additional primary doses administered to immunocompromised persons, which could result in reduced IRRs because of lower VE in this population. Second, this ecological study lacked multivariable adjustments, and causality could not be determined. Possible differences in testing, infection-derived immunity, waning of vaccine-derived immunity, or prevention behaviors by age and vaccination status might partly explain differences in rates between groups; trends are likely affected by temporal changes in testing or reporting. Third, national variant prevalence estimates were used, but prevalence differed by jurisdiction over time. Fourth, variable data linkage completeness might have resulted in misclassifications (e.g., booster doses not being linked to primary series) that could influence IRR estimates (5). Finally, these data represent 62% of the overall U.S. population, and therefore might not be generalizable.
1.Scobie HM, Johnson AG, Suthar AB, et al. Monitoring incidence of COVID-19 cases, hospitalizations, and deaths, by vaccination status—13 US jurisdictions, April 4–July 17, 2021. MMWR Morb Mortal Wkly Rep 2021;70:1284–90. https://doi.org/10.15585/mmwr.mm7037e1 PMID:34529637
2.Paz-Bailey G, Sternberg M, Kugeler K, et al. Covid-19 rates by time since vaccination during Delta variant predominance. NEJM Evidence 2021. Epub December 20, 2021. https://doi.org/10.1056/EVIDoa2100057
3.CDC. Rates of COVID-19 cases and deaths by vaccination status. Atlanta, GA: US Department of Health and Human Services, CDC; 2021. https://covid.cdc.gov/covid-data-tracker/#rates-by-vaccine-status
4.CDC. Rates of laboratory-confirmed COVID-19 hospitalizations by vaccination status. Atlanta, GA: US Department of Health and Human Services, CDC; 2021. https://covid.cdc.gov/covid-data-tracker/#covidnet-hospitalizations-vaccination
5.Fast HE, Zell E, Murthy BP, et al. Booster and additional primary dose COVID-19 vaccinations among adults aged ≥65 years—United States, August 13, 2021–November 19, 2021. MMWR Morb Mortal Wkly Rep 2021;70:1735–9. https://doi.org/10.15585/mmwr.mm7050e2 PMID:34914672
6.CDC COVID-19 Response Team. SARS-CoV-2 B.1.1.529 (Omicron) variant—United States, December 1–8, 2021. MMWR Morb Mortal Wkly Rep 2021;70:1731–4. https://doi.org/10.15585/mmwr.mm7050e1 PMID:34914670
Mar 24, 2022 · COVID-19–Associated Hospitalizations Among Adults During SARS-CoV-2 Delta and Omicron Variant Predominance, by Race/Ethnicity and Vaccination Status — COVID-NET, 14 States, July 2021–January 2022. Weekly / March 25, 2022 / 71 (12);466–473. Print. On March 18, 2022, this report was posted online as an MMWR Early Release.
Jul 15, 2021 · Summary. What is already known about this topic? The SARS-CoV-2 B.1.617.2 (Delta) variant emerged in India and is currently widespread. Evidence suggests that it is potentially more transmissible than other variants. What is added by this report?
