TY - JOUR
T1 - Seroprevalence of anti-SARS-CoV-2 antibodies in Iquitos, Peru in July and August, 2020
T2 - a population-based study
AU - Álvarez-Antonio, Carlos
AU - Meza-Sánchez, Graciela
AU - Calampa, Carlos
AU - Casanova, Wilma
AU - Carey, Cristiam
AU - Alava, Freddy
AU - Rodríguez-Ferrucci, Hugo
AU - Quispe, Antonio M.
N1 - Funding Information:
This work was supported by the Loreto Health Directorate (DIRESA) and the Peruvian Ministry of Health. DIRESA, Loreto also provided the census information necessary for the random selection of households. We thank all the health professionals, administrative personnel, and other health-care workers who collaborated in this study, and all study participants. Additionally, we would like to thank Enrique Mendoza (Futurum Research) for his support in elaborating the study's graphics and Valerie Paz Soldan (Universidad Peruana Cayetano Heredia), Amy Morrison (US Naval Medical Research Unit 6), and Margaret Kosek (University of Virginia) for their review and feedback on the writing of the manuscript. This study is the result of the efforts of researchers from Loreto, all of whom also suffered from COVID-19 during the Iquitos epidemic, and the trust and generosity of more than 700 participants who have understood the importance of providing time, information, and blood samples to learn about the COVID-19 epidemic in Iquitos. The findings and conclusions presented in this report are those of the authors and do not necessarily reflect the Peruvian Ministry of Health's official position.
Funding Information:
This work was supported by the Loreto Health Directorate (DIRESA) and the Peruvian Ministry of Health. DIRESA, Loreto also provided the census information necessary for the random selection of households. We thank all the health professionals, administrative personnel, and other health-care workers who collaborated in this study, and all study participants. Additionally, we would like to thank Enrique Mendoza (Futurum Research) for his support in elaborating the study's graphics and Valerie Paz Soldan (Universidad Peruana Cayetano Heredia), Amy Morrison (US Naval Medical Research Unit 6), and Margaret Kosek (University of Virginia) for their review and feedback on the writing of the manuscript. This study is the result of the efforts of researchers from Loreto, all of whom also suffered from COVID-19 during the Iquitos epidemic, and the trust and generosity of more than 700 participants who have understood the importance of providing time, information, and blood samples to learn about the COVID-19 epidemic in Iquitos. The findings and conclusions presented in this report are those of the authors and do not necessarily reflect the Peruvian Ministry of Health's official position.
Publisher Copyright:
© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license
PY - 2021/7
Y1 - 2021/7
N2 - Background: Detection of anti-SARS-CoV-2 antibodies among people at risk of infection is crucial for understanding both the past transmission of COVID-19 and vulnerability of the population to continuing transmission and, when done serially, the intensity of ongoing transmission over an interval in a community. We aimed to estimate the seroprevalence of COVID-19 in a representative population-based cohort in Iquitos, one of the regions with the highest mortality rates from COVID-19 in Peru, where a devastating number of cases occurred in March, 2020. Methods: We did a population-based study of SARS-CoV-2 transmission in Iquitos at two timepoints: July 13–18, 2020 (baseline), and Aug 13–18, 2020 (1-month follow-up). We obtained a geographically stratified representative sample of the city population using the 2017 census data, which was updated on Jan 20, 2020. We included people who were inhabitants of Iquitos since COVID-19 was identified in Peru (March 6, 2020) or earlier. We excluded people living in institutions, people receiving any pharmacological treatment for COVID-19, people with any contraindication for phlebotomy, and health workers or individuals living with an active health worker. We tested each participant for IgG and IgM anti-SARS-CoV-2 antibodies using the COVID-19 IgG/IgM Rapid Test (Zhejiang Orient Gene Biotech, China). We used survey analysis methods to estimate seroprevalence accounting for the sampling design effect and test performance characteristics. Findings: We identified 726 eligible individuals and enrolled a total of 716 participants (99%), distributed across 40 strata (four districts, two sexes, and five age groups). We excluded ten individuals who: did not have consent from a parent or legal representative (n=3), had moved to Iquitos after March 6, 2020 (n=3), were in transit (n=2), or had respiratory symptoms (n=1). After adjusting for the study sampling effects and sensitivity and specificity of the test, we estimated a seroprevalence of 70% (95% CI 67–73) at baseline and 66% (95% CI 62–70) at 1 month of follow-up, with a test-retest positivity of 65% (95% CI 61–68), and an incidence of new exposures of 2% (95% CI 1–3). We observed significant differences in the seroprevalence between age groups, with participants aged 18–29 years having lower seroprevalence than those aged younger than 12 years (prevalence ratio 0·85 [95% CI 0·73–0·98]; p=0·029). Interpretation: After the first epidemic peak, Iquitos had one of the highest rates of seroprevalence of anti-SARS-CoV-2 antibodies worldwide. Nevertheless, the city experienced a second wave starting in January, 2021, probably due to the emergence of the SARS-CoV-2 P1 variant, which has shown higher transmissibility and reinfection rates. Funding: Dirección Regional de Salud de Loreto (DIRESA), Loreto, Peru. Translation: For the Spanish translation of the abstract see Supplementary Materials section.
AB - Background: Detection of anti-SARS-CoV-2 antibodies among people at risk of infection is crucial for understanding both the past transmission of COVID-19 and vulnerability of the population to continuing transmission and, when done serially, the intensity of ongoing transmission over an interval in a community. We aimed to estimate the seroprevalence of COVID-19 in a representative population-based cohort in Iquitos, one of the regions with the highest mortality rates from COVID-19 in Peru, where a devastating number of cases occurred in March, 2020. Methods: We did a population-based study of SARS-CoV-2 transmission in Iquitos at two timepoints: July 13–18, 2020 (baseline), and Aug 13–18, 2020 (1-month follow-up). We obtained a geographically stratified representative sample of the city population using the 2017 census data, which was updated on Jan 20, 2020. We included people who were inhabitants of Iquitos since COVID-19 was identified in Peru (March 6, 2020) or earlier. We excluded people living in institutions, people receiving any pharmacological treatment for COVID-19, people with any contraindication for phlebotomy, and health workers or individuals living with an active health worker. We tested each participant for IgG and IgM anti-SARS-CoV-2 antibodies using the COVID-19 IgG/IgM Rapid Test (Zhejiang Orient Gene Biotech, China). We used survey analysis methods to estimate seroprevalence accounting for the sampling design effect and test performance characteristics. Findings: We identified 726 eligible individuals and enrolled a total of 716 participants (99%), distributed across 40 strata (four districts, two sexes, and five age groups). We excluded ten individuals who: did not have consent from a parent or legal representative (n=3), had moved to Iquitos after March 6, 2020 (n=3), were in transit (n=2), or had respiratory symptoms (n=1). After adjusting for the study sampling effects and sensitivity and specificity of the test, we estimated a seroprevalence of 70% (95% CI 67–73) at baseline and 66% (95% CI 62–70) at 1 month of follow-up, with a test-retest positivity of 65% (95% CI 61–68), and an incidence of new exposures of 2% (95% CI 1–3). We observed significant differences in the seroprevalence between age groups, with participants aged 18–29 years having lower seroprevalence than those aged younger than 12 years (prevalence ratio 0·85 [95% CI 0·73–0·98]; p=0·029). Interpretation: After the first epidemic peak, Iquitos had one of the highest rates of seroprevalence of anti-SARS-CoV-2 antibodies worldwide. Nevertheless, the city experienced a second wave starting in January, 2021, probably due to the emergence of the SARS-CoV-2 P1 variant, which has shown higher transmissibility and reinfection rates. Funding: Dirección Regional de Salud de Loreto (DIRESA), Loreto, Peru. Translation: For the Spanish translation of the abstract see Supplementary Materials section.
UR - http://www.scopus.com/inward/record.url?scp=85107296608&partnerID=8YFLogxK
U2 - 10.1016/S2214-109X(21)00173-X
DO - 10.1016/S2214-109X(21)00173-X
M3 - Original Article
C2 - 34022148
AN - SCOPUS:85107296608
SN - 2214-109X
VL - 9
SP - e925-e931
JO - The Lancet Global Health
JF - The Lancet Global Health
IS - 7
ER -