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Has Omicron Changed the Evolution of the Pandemic?
Lundberg, Alexander L; Lorenzo-Redondo, Ramon; Ozer, Egon A; Hawkins, Claudia A; Hultquist, Judd F; Welch, Sarah B; Prasad, P V Vara; Oehmke, James F; Achenbach, Chad J; Murphy, Robert L; White, Janine I; Havey, Robert J; Post, Lori Ann.
  • Lundberg AL; Buehler Center for Health Policy and Economics, Robert J. Havey, MD Institute for Global Health, Northwestern University, Chicago, IL, United States.
  • Lorenzo-Redondo R; Department of Emergency Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
  • Ozer EA; Department of Medicine, Division of Infectious Diseases, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
  • Hawkins CA; Center for Pathogen Genomics and Microbial Evolution, Robert J. Havey, MD Institute for Global Health, Northwestern University, Chicago, IL, United States.
  • Hultquist JF; Department of Medicine, Division of Infectious Diseases, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
  • Welch SB; Center for Pathogen Genomics and Microbial Evolution, Robert J. Havey, MD Institute for Global Health, Northwestern University, Chicago, IL, United States.
  • Prasad PVV; Department of Medicine, Division of Infectious Diseases, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
  • Oehmke JF; Center for Global Communicable and Emerging Infectious Diseases, Robert J. Havey, MD Institute for Global Health, Northwestern University, Chicago, IL, United States.
  • Achenbach CJ; Department of Medicine, Division of Infectious Diseases, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
  • Murphy RL; Center for Pathogen Genomics and Microbial Evolution, Robert J. Havey, MD Institute for Global Health, Northwestern University, Chicago, IL, United States.
  • White JI; Buehler Center for Health Policy and Economics, Robert J. Havey, MD Institute for Global Health, Northwestern University, Chicago, IL, United States.
  • Havey RJ; Department of Emergency Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
  • Post LA; Sustainable Intensification Innovation Lab, Kansas State University, Manhattan, KS, United States.
JMIR Public Health Surveill ; 8(1): e35763, 2022 01 31.
Article in English | MEDLINE | ID: covidwho-2198032
ABSTRACT

BACKGROUND:

Variants of the SARS-CoV-2 virus carry differential risks to public health. The Omicron (B.1.1.529) variant, first identified in Botswana on November 11, 2021, has spread globally faster than any previous variant of concern. Understanding the transmissibility of Omicron is vital in the development of public health policy.

OBJECTIVE:

The aim of this study is to compare SARS-CoV-2 outbreaks driven by Omicron to those driven by prior variants of concern in terms of both the speed and magnitude of an outbreak.

METHODS:

We analyzed trends in outbreaks by variant of concern with validated surveillance metrics in several southern African countries. The region offers an ideal setting for a natural experiment given that most outbreaks thus far have been driven primarily by a single variant at a time. With a daily longitudinal data set of new infections, total vaccinations, and cumulative infections in countries in sub-Saharan Africa, we estimated how the emergence of Omicron has altered the trajectory of SARS-CoV-2 outbreaks. We used the Arellano-Bond method to estimate regression coefficients from a dynamic panel model, in which new infections are a function of infections yesterday and last week. We controlled for vaccinations and prior infections in the population. To test whether Omicron has changed the average trajectory of a SARS-CoV-2 outbreak, we included an interaction between an indicator variable for the emergence of Omicron and lagged infections.

RESULTS:

The observed Omicron outbreaks in this study reach the outbreak threshold within 5-10 days after first detection, whereas other variants of concern have taken at least 14 days and up to as many as 35 days. The Omicron outbreaks also reach peak rates of new cases that are roughly 1.5-2 times those of prior variants of concern. Dynamic panel regression estimates confirm Omicron has created a statistically significant shift in viral spread.

CONCLUSIONS:

The transmissibility of Omicron is markedly higher than prior variants of concern. At the population level, the Omicron outbreaks occurred more quickly and with larger magnitude, despite substantial increases in vaccinations and prior infections, which should have otherwise reduced susceptibility to new infections. Unless public health policies are substantially altered, Omicron outbreaks in other countries are likely to occur with little warning.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Pandemics / COVID-19 Type of study: Experimental Studies / Prognostic study Topics: Vaccines / Variants Limits: Humans Language: English Journal: JMIR Public Health Surveill Year: 2022 Document Type: Article Affiliation country: 35763

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Pandemics / COVID-19 Type of study: Experimental Studies / Prognostic study Topics: Vaccines / Variants Limits: Humans Language: English Journal: JMIR Public Health Surveill Year: 2022 Document Type: Article Affiliation country: 35763