TY - JOUR
T1 - SARS-CoV-2 Attack Rate and Population Immunity in Southern New England, March 2020 to May 2021
AU - Tran, Thu Nguyen Anh
AU - Wikle, Nathan B.
AU - Yang, Fuhan
AU - Inam, Haider
AU - Leighow, Scott
AU - Gentilesco, Bethany
AU - Chan, Philip
AU - Albert, Emmy
AU - Strong, Emily R.
AU - Pritchard, Justin R.
AU - Hanage, William P.
AU - Hanks, Ephraim M.
AU - Crawford, Forrest W.
AU - Boni, Maciej F.
N1 - Funding Information:
Surveillance. Dr Hanage is funded by award No. U54 GM088558 from the National Institute of General Medical Sciences. Ms Albert is funded by grant No. NSF DMR-1420620 from the Penn State Materials Research Science and Engineering Center, Center for Nanoscale Science. Dr Hanks was partially supported by grant No. DMS-2015273 from the National Science Foundation. Dr Crawford is supported by Cooperative Agreement No. 6NU50CK000524-01 from the Centers for Disease Control and Prevention, funds from the COVID-19 Paycheck Protection Program and Health Care Enhancement Act, NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development grant No. 1DP2HD091799-01, and the Pershing Square Foundation.
Funding Information:
Funding/Support: Dr Boni and Ms Tran are funded by grant No. INV-005517 from the Bill and Melinda Gates Foundation. Ms Yang is supported by contract No. HHS N272201400007C from the National Institutes of Health (NIH) National Institute of Allergy and Infectious Diseases Center of Excellence in Influenza Research and
Publisher Copyright:
© 2022 BMJ Publishing Group. All rights reserved.
PY - 2022/5/26
Y1 - 2022/5/26
N2 - Importance: In emergency epidemic and pandemic settings, public health agencies need to be able to measure the population-level attack rate, defined as the total percentage of the population infected thus far. During vaccination campaigns in such settings, public health agencies need to be able to assess how much the vaccination campaign is contributing to population immunity; specifically, the proportion of vaccines being administered to individuals who are already seropositive must be estimated. Objective: To estimate population-level immunity to SARS-CoV-2 through May 31, 2021, in Rhode Island, Massachusetts, and Connecticut. Design, Setting, and Participants: This observational case series assessed cases, hospitalizations, intensive care unit occupancy, ventilator occupancy, and deaths from March 1, 2020, to May 31, 2021, in Rhode Island, Massachusetts, and Connecticut. Data were analyzed from July 2021 to November 2021. Exposures: COVID-19-positive test result reported to state department of health. Main Outcomes and Measures: The main outcomes were statistical estimates, from a bayesian inference framework, of the percentage of individuals as of May 31, 2021, who were (1) previously infected and vaccinated, (2) previously uninfected and vaccinated, and (3) previously infected but not vaccinated. Results: At the state level, there were a total of 1160435 confirmed COVID-19 cases in Rhode Island, Massachusetts, and Connecticut. The median age among individuals with confirmed COVID-19 was 38 years. In autumn 2020, SARS-CoV-2 population immunity (equal to the attack rate at that point) in these states was less than 15%, setting the stage for a large epidemic wave during winter 2020 to 2021. Population immunity estimates for May 31, 2021, were 73.4% (95% credible interval [CrI], 72.9%-74.1%) for Rhode Island, 64.1% (95% CrI, 64.0%-64.4%) for Connecticut, and 66.3% (95% CrI, 65.9%-66.9%) for Massachusetts, indicating that more than 33% of residents in these states were fully susceptible to infection when the Delta variant began spreading in July 2021. Despite high vaccine coverage in these states, population immunity in summer 2021 was lower than planned owing to an estimated 34.1% (95% CrI, 32.9%-35.2%) of vaccines in Rhode Island, 24.6% (95% CrI, 24.3%-25.1%) of vaccines in Connecticut, and 27.6% (95% CrI, 26.8%-28.6%) of vaccines in Massachusetts being distributed to individuals who were already seropositive. Conclusions and Relevance: These findings suggest that future emergency-setting vaccination planning may have to prioritize high vaccine coverage over optimized vaccine distribution to ensure that sufficient levels of population immunity are reached during the course of an ongoing epidemic or pandemic.
AB - Importance: In emergency epidemic and pandemic settings, public health agencies need to be able to measure the population-level attack rate, defined as the total percentage of the population infected thus far. During vaccination campaigns in such settings, public health agencies need to be able to assess how much the vaccination campaign is contributing to population immunity; specifically, the proportion of vaccines being administered to individuals who are already seropositive must be estimated. Objective: To estimate population-level immunity to SARS-CoV-2 through May 31, 2021, in Rhode Island, Massachusetts, and Connecticut. Design, Setting, and Participants: This observational case series assessed cases, hospitalizations, intensive care unit occupancy, ventilator occupancy, and deaths from March 1, 2020, to May 31, 2021, in Rhode Island, Massachusetts, and Connecticut. Data were analyzed from July 2021 to November 2021. Exposures: COVID-19-positive test result reported to state department of health. Main Outcomes and Measures: The main outcomes were statistical estimates, from a bayesian inference framework, of the percentage of individuals as of May 31, 2021, who were (1) previously infected and vaccinated, (2) previously uninfected and vaccinated, and (3) previously infected but not vaccinated. Results: At the state level, there were a total of 1160435 confirmed COVID-19 cases in Rhode Island, Massachusetts, and Connecticut. The median age among individuals with confirmed COVID-19 was 38 years. In autumn 2020, SARS-CoV-2 population immunity (equal to the attack rate at that point) in these states was less than 15%, setting the stage for a large epidemic wave during winter 2020 to 2021. Population immunity estimates for May 31, 2021, were 73.4% (95% credible interval [CrI], 72.9%-74.1%) for Rhode Island, 64.1% (95% CrI, 64.0%-64.4%) for Connecticut, and 66.3% (95% CrI, 65.9%-66.9%) for Massachusetts, indicating that more than 33% of residents in these states were fully susceptible to infection when the Delta variant began spreading in July 2021. Despite high vaccine coverage in these states, population immunity in summer 2021 was lower than planned owing to an estimated 34.1% (95% CrI, 32.9%-35.2%) of vaccines in Rhode Island, 24.6% (95% CrI, 24.3%-25.1%) of vaccines in Connecticut, and 27.6% (95% CrI, 26.8%-28.6%) of vaccines in Massachusetts being distributed to individuals who were already seropositive. Conclusions and Relevance: These findings suggest that future emergency-setting vaccination planning may have to prioritize high vaccine coverage over optimized vaccine distribution to ensure that sufficient levels of population immunity are reached during the course of an ongoing epidemic or pandemic.
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U2 - 10.1001/jamanetworkopen.2022.14171
DO - 10.1001/jamanetworkopen.2022.14171
M3 - Article
C2 - 35616938
AN - SCOPUS:85130834824
SN - 2574-3805
VL - 5
SP - E2214171
JO - JAMA network open
JF - JAMA network open
IS - 5
ER -