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Nov 4, 2021 · The Delta variant also shifted which states were hit hardest by COVID-19 deaths. Before July, New Jersey was the worst-hit state for cumulative COVID-19 death rates, with 297 deaths per 100,000 people. But the Delta surge drove cumulative death rates in Mississippi, Alabama, and Louisiana over 300 per 100,000 residents.
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 as a proxy for waning immunity during a period when the SARS-CoV-2 delta variant was predominant (>95%) in the United States.
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On September 10, 2021, this report was posted online as an MMWR Early Release.
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In 13 U.S. jurisdictions, rates of COVID-19 cases, hospitalizations, and deaths were substantially higher in persons not fully vaccinated compared with those in fully vaccinated persons, similar to findings in other reports (2,3). After the week of June 20, 2021, when the SARS-CoV-2 Delta variant became predominant, the percentage of fully vaccinated persons among cases increased more than expected for the given vaccination coverage and a constant VE. The IRR for cases among persons not fully vaccinated versus fully vaccinated decreased substantially; IRRs for hospitalizations and deaths changed less overall, but moderately among adults aged ≥65 years. Findings from this crude analysis of surveillance data are consistent with recent studies reporting decreased VE against confirmed infection but not hospitalization or death, during a period of Delta variant predominance and potential waning of vaccine-induced population immunity (4–6).†††
The findings in this report are subject to at least five limitations. First, combining unvaccinated and partially vaccinated persons resulted in lower IRR and VE estimates. Second, variable linkage of case surveillance, vaccination, hospitalization, and mortality data might have resulted in misclassifications that could influence IRR estimates; no substantial differences in ascertainment of outcomes by vaccination status were noted in jurisdictions that were able to assess this. Lags in reporting of deaths might have affected the second period differentially. Third, this was an ecological study in which IRRs lacked multivariable adjustments and causality could not be assessed (i.e., possible differences in testing or behaviors in vaccinated and unvaccinated persons). VE is being assessed through ongoing controlled studies. Fourth, the period when the SARS-CoV-2 Delta variant reached ≥50% overall prevalence was assumed to be the first week when most cases were infected with the Delta variant, but the week varied by jurisdiction. Finally, the data assessed from 13 jurisdictions accounted for 25% of the U.S. population, and therefore might not be generalizable.
1.World Health Organization. Guidance on conducting vaccine effectiveness evaluations in the setting of new SARS-CoV-2 variants: interim guidance, 22 July 2021. Geneva, Switzerland: World Health Organization; 2021. https://www.who.int/publications/i/item/WHO-2019-nCoV-vaccine_effectiveness-variants-2021.1external icon
2.Havers FP, Pham H, Taylor CA, et al. COVID-19–associated hospitalizations among vaccinated and unvaccinated adults ≥18 years—COVID-NET, 13 states, January 1–July 24, 2021. medRxiv [Preprint posted online August 29, 2021]. https://www.medrxiv.org/content/10.1101/2021.08.27.21262356v1external icon
3.Griffin JB, Haddix M, Danza P, et al. SARS-CoV-2 infections and hospitalizations among persons aged ≥16 years, by vaccination status—Los Angeles County, California, May 1–July 25, 2021. MMWR Morb Mortal Wkly Rep 2021;70:1170–6. https://doi.org/10.15585/mmwr.mm7034e5external icon PMID:34437525external icon
4.Fowlkes A, Gaglani M, Groover K, Thiese MS, Tyner H, Ellingson K; HEROES-RECOVER Cohorts. Effectiveness of COVID-19 vaccines in preventing SARS-CoV-2 infection among frontline workers before and during B.1.617.2 (Delta) variant predominance—eight U.S. locations, December 2020–August 2021. MMWR Morb Mortal Wkly Rep 2021;70:1167–9. https://doi.org/10.15585/mmwr.mm7034e4external icon PMID:34437521external icon
5.Rosenberg ES, Holtgrave DR, Dorabawila V, et al. New COVID-19 cases and hospitalizations among adults, by vaccination status—New York, May 3–July 25, 2021. MMWR Morb Mortal Wkly Rep 2021;70:1150–5. https://doi.org/10.15585/mmwr.mm7034e1external icon PMID:34437517external icon
6.Tenforde MW, Self WH, Naioti EA, et al.; IVY Network Investigators; IVY Network. Sustained effectiveness of Pfizer-BioNTech and Moderna vaccines against COVID-19 associated hospitalizations among adults—United States, March–July 2021. MMWR Morb Mortal Wkly Rep 2021;70:1156–62. https://doi.org/10.15585/mmwr.mm7034e2external icon PMID:34437524external icon
- Heather M. Scobie, Amelia G. Johnson, Amitabh B. Suthar, Rachel Severson, Nisha B. Alden, Sharon Bal...
- 2021
For the booster dose analysis, age-standardized rates include ages 18 years and older from September 19, 2021 through December 25, 2021, ages 12 years and older from December 26, 2021, and ages 5 years and older from June 5, 2022 onwards. Small numbers could contribute to less precision when calculating death rates among some groups.
Jul 11, 2023 · Abstract. The SARS-CoV-2 Delta variant, first identified in October 2020, quickly became the dominant variant worldwide. We used publicly available data to explore the relationship between illness and death (peak case rates, death rates, case-fatality rates) and selected predictors (percentage vaccinated, percentage of the population >65 years, population density, testing volume, index of ...
Sep 15, 2022 · The risk for COVID-19–associated mortality increases with age, disability, and underlying medical conditions (1).Early in the emergence of the Omicron variant of SARS-CoV-2, the virus that causes COVID-19, mortality among hospitalized COVID-19 patients was lower than that during previous pandemic peaks (2–5), and some health authorities reported that a substantial proportion of COVID-19 ...
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Jan 27, 2022 · Peaks in age-standardized case and death rates occurred during August (>95% of infections attributed to the Delta variant); case rates also peaked during the 2 weeks ending December 18 and 25 (39% and 72% infections attributed to the Omicron variant, respectively) .
