Estudios originales
Medwave 2022;22(2):e002553 doi: 10.5867/medwave.2022.03.002553
Seroprevalencia y estimación del impacto de la infección por SARS-CoV-2 en personas mayores residentes en centros de larga estadía en Chile
Seroprevalence and estimation of the impact of SARS-CoV-2 infection in older adults residing in Long-term Care Facilities in Chile
Paola Rubilar, Macarena Hirmas, Isabel Matute, Jorge Browne, Cedric Little, Gonzalo Ruz, Ximena Aguilera, Carlos Ávila, Pablo Vial, Tania Gutknecht Mackenzie
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Resumen

Introducción
Las personas mayores tienen más riesgo de enfermar gravemente y fallecer por COVID-19. Esta vulnerabilidad aumenta en quienes viven en establecimientos de larga estadía, debido a hacinamiento, mayor dependencia física y contacto con los trabajadores. La evidencia sobre el impacto de la pandemia de estos establecimientos en países de medianos y bajos ingresos ha sido escasa. El objetivo es determinar la seroprevalencia de la infección por SARS-CoV-2 en personas mayores que residen en establecimientos de larga estadía. Así como estimar el impacto global de la infección después de la primera ola de la pandemia.

Métodos
Diseño transversal con 2099 residentes en tres regiones de Chile, realizado entre septiembre y noviembre 2020. Anticuerpos fueron medidos con test rápido contra SARS-CoV-2. Se estimó el impacto de la infección con los residentes seropositivos, los residentes con antecedentes de reacción en cadena de la polimerasa de transcripción inversa positiva, y residentes que murieron por COVID-19. Análisis bivariado entre el resultado serológico y región, sexo, edad, antecedentes de COVID-19 y dependencia física fueron realizados. Además, realizamos un análisis de correlación entre la seroprevalencia de los centros por municipio y la tasa acumulada de casos confirmados.

Resultados
La seroprevalencia de anticuerpos en las tres regiones fue 14,7% (intervalo de confianza del 95%: 13,2 a 16,3%). El impacto real de la infección se estimó en 46,4% y la tasa de letalidad en 19,6%. La seroprevalencia de los residentes de los centros por comuna se correlacionó positiva y significativamente con la frecuencia de la enfermedad a nivel comunal.

Conclusiones
Seroprevalencia superior a la de la población general, observándose un alto impacto de la infección por COVID-19 al final de la primera ola de la pandemia. El lugar en el que se encuentran los establecimientos está directamente relacionado con la tasa de seroprevalencia en ellos. Sistemas de vigilancia epidemiológica deben aplicarse con prontitud para establecer medidas de prevención y control.


 

Solo esta disponible la versión en inglés.

 

Introduction
Older adults are at a higher risk of severe illness and death from COVID-19. This vulnerability increases in those who live in long-term care facilities due to overcrowding, greater physical dependence, and contact with health workers. Evidence on the impact of the pandemic on these establishments in lowand middle-income countries has been scant. This study aims to determine the seroprevalence of SARS-CoV-2 in older people residing in long-term care facilities and estimate the impact of infection after the first wave of the pandemic.

Methods
A cross-sectional design with 2099 residents in three regions of Chile was carried out between September and November 2020. Measurement of antibodies was performed with a rapid test. The impact of SARS-CoV-2 infection was estimated with seropositive residents, those who had a history of positive polymerase chain reaction tests, and those who died from COVID-19. Bivariate analysis with the region, sex, age, history of COVID-19, physical dependence, and serological results were performed. In addition, we performed a correlation analysis between the seroprevalence of the centers by the municipality and the rate of confirmed cases.

Results
The seroprevalence of SARS-CoV-2 antibodies in the three regions was 14.7% (95% confidence interval: 13.2 to 16.3%), the infection impact was 46.4%, and the fatality rate was 19.6%. A significant correlation was found between the seroprevalence of older adults residing in long-term care facilities and the cumulative incidence by municipalities.

Conclusions
The seroprevalence of older adults residing in long-term care facilities was higher than the general population. The high impact of infection among this population at the end of the first wave of the COVID-19 pandemic is similar to other countries. The centers' environment is directly related to COVID-19 infection. Morbidity and mortality monitoring systems should be implemented promptly to establish prevention and control measures.

Autores: Paola Rubilar[1], Macarena Hirmas[1], Isabel Matute[1], Jorge Browne[2], Cedric Little[3], Gonzalo Ruz[3], Ximena Aguilera[1], Carlos Ávila[4], Pablo Vial[5], Tania Gutknecht Mackenzie[6]

Filiación:
[1] Centro de Epidemiología y Políticas de Salud, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
[2] Servicio Nacional del Adulto Mayor, Santiago, Chile
[3] Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Santiago, Chile
[4] Ministerio de Ciencia, Tecnología, Conocimiento e Innovación, Santiago, Chile
[5] Instituto de Ciencias e Innovación en Medicina (ICIM), Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
[6] Fundación Chile, Santiago, Chile

E-mail: paolarubilar@udd.cl

Citación: Rubilar P, Hirmas M, Matute I, Browne J, Little C, Ruz G, et al. Seroprevalence and estimation of the impact of SARS-CoV-2 infection in older adults residing in Long-term Care Facilities in Chile. Medwave 2022;22(2):e002553 doi: 10.5867/medwave.2022.03.002553

Fecha de envío: 30/12/2021

Fecha de aceptación: 16/3/2022

Fecha de publicación: 7/4/2022

Origen: No solicitado

Tipo de revisión: Con revisión externa por tres pares revisores, a doble ciego

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  1. Vellas C, Delobel P, de Souto Barreto P, Izopet J. COVID-19, Virology and Geroscience: A Perspective. J Nutr Health Aging. 2020;24: 685–691. | CrossRef | Link |
  2. Denis M, Vandeweerd V, Verbeeke R, Laudisoit A, Reid T, Hobbs E, et al. Covipendium: Information available to support the development of medical countermeasures and interventions against COVID-19. Transdisciplinary Insights. 2020;4: 1–296. | CrossRef | Link |
  3. Fischer RJ, Morris KK, McCorkel LA, Case SM, Pham HH, et al. An Ounce of Prevention: Reducing the Risk of COVID-19 Transmission in Long-Term Care Facilities. J Geriatr Med Gerontol. 2020;6. | CrossRef | Link |
  4. Battisti NML, Mislang AR, Cooper L, O’Donovan A, Audisio RA, Cheung K-L, et al. Adapting care for older cancer patients during the COVID-19 pandemic: Recommendations from the International Society of Geriatric Oncology (SIOG) COVID-19 Working Group. J Geriatr Oncol. 2020;11: 1190–1198. | CrossRef |
  5. Sociedad Española de Médicos de Atención Primaria (Semergen). Síntomas atípicos de Covid-19 en pacientes crónicos mayores. 6 Jul 2020. | Link |
  6. Suárez-González A, Livingston G, Cahill S, Hennelly N, Dawson WD, Weidner W, et al. Impact and mortality of COVID-19 on people living with dementia: cross-country report. 5 Jul 2020. | Link |
  7. Centers for Disease Control and Prevention (CDC). Responding to coronavirus (COVID-19) in nursing homes. | Link |
  8. International Long-term Care Policy Network (ILPN) and CarInternational Long-term Care Policy Network (ILPN) and Care Policy and Evaluation Centre (CPEC) at the London School of Economics and Political Science (LSE). International reports on COVID-19 and Long-Term Care. Resources to support community and institutional Long-Term Care responses to COVID-19; 2021. | Link |
  9. Vena A, Berruti M, Adessi A, Blumetti P, Brignole M, Colognato R, et al. Prevalence of Antibodies to SARS-CoV-2 in Italian Adults and Associated Risk Factors. J Clin Med. 2020;9. | CrossRef | Link |
  10. Shi SM, Bakaev I, Chen H, Travison TG, Berry SD. Risk Factors, Presentation, and Course of Coronavirus Disease 2019 in a Large, Academic Long-Term Care Facility. J Am Med Dir Assoc. 2020;21: 1378–1383. | CrossRef |
  11. Byrd W, Salcher-Konrad M, Smith S, Comas-Herrera A. What Long-Term Care Interventions and Policy Measures Have Been Studied During the Covid-19 Pandemic? Findings from a Rapid Mapping Review of the Scientific Evidence Published During 2020. JLTC. 2021;0: 423. | CrossRef | Link |
  12. Wachholz PA, Jacinto AF, Melo RC de, Dinamarca-Montecinos JL, Boas PJFV. Challenges in long-term care facilities for older adults in Hispanic American countries. Geriatr Gerontol Aging.2020;14: 259–266. | CrossRef | Link |
  13. Kimball A, Hatfield KM, Arons M, James A, Taylor J, Spicer K, et al. Asymptomatic and Presymptomatic SARS-CoV- 2 Infections in Residents of a Long-Term Care Skilled Nursing Facility - King County, Washington, March 2020. MMWR Morb Mortal Wkly Rep. 2020;69: 377–381. | CrossRef | Link |
  14. Graham NSN, Junghans C, Downes R, Sendall C, Lai H, McKirdy A, et al. SARS-CoV-2 infection, clinical features and outcome of COVID-19 in United Kingdom nursing homes. J Infect. 2020;81: 411–419. | CrossRef | Link |
  15. Roxby AC, Greninger AL, Hatfield KM, Lynch JB, Dellit TH, James A, et al. Detection of SARS-COV-2 Among Residents and Staff Members of an Independent and Assisted Living Community for Older Adults - Seattle, Washington, 2020. MMWR Morb Mortal Wkly Rep. 2020;69: 416–418. | CrossRef |
  16. Ochieng N, Chidambaram P, Garfield R, Neuman T. 2021; 1–20. | Link |
  17. Organización Mundial de la Salud (OMS). Protocolo para estudios seroepidemiológicos poblacionales sobre la COVID-19, con estratificación por edades. 5 Jul 2020. | Link |
  18. Centers for Disease Control and Prevention. COVID-19 Serology Surveillance Strategy. COVID-19 Serology Surveillance. Data & Surveillance; 6 Jul 2021. | Link |
  19. Departamento de Estadísticas e Información de Salud. Informe semanal de defunciones por COVID-19. 2021. | Link |
  20. Departamento de Epidemiología Ministerio de Salud del Gobierno de Chile. Informe Epidemiológico No 128. Enfermedad por SARS-CoV-2. Chile. 2021. | Link |
  21. Massad C, Herrera F. Condiciones de vida de las personas mayores al interior de establecimientos de larga estadía para adultos mayores de SENAMA. 2017. | Link |
  22. Servicio Nacional del Adulto Mayor. Protocolo para centros residenciales de personas mayores para la prevención y atención del COVID-19. Santiago; 2020. | Link |
  23. Innovita Beijing and Innovita Tangshan. INNOVITA 2019-nCoV IgM/IgG Combo Test. 2019. | Link |
  24. Departamento de Epidemiología del Ministerio de Salud del Gobierno de Chile. Informe Epidemiológico N°68. Enfermedad por SARS-CoV-2 (COVID-19). 2020. | Link |
  25. Sargento ESG. Epitools Epidemiological Calculators. usvet. 2018. | Link |
  26. Vial P, González C, Icaza G, Ramirez-Santana M, Quezada-Gaete R, Núñez-Franz L, et al. Seroprevalence, spatial distribution, and social determinants of SARS-CoV-2 in three urban centers of Chile. BMC Infect Dis. 2022;22. | CrossRef | Link |
  27. Ministerio de Salud de Chile. Situación Nacional de COVID-19 en Chile. 2021. | Link |
  28. Jeffery-Smith A, Dun-Campbell K, Janarthanan R, Fok J, Crawley-Boevey E, Vusirikala A, et al. Infection and transmission of SARS-CoV-2 in London care homes reporting no cases or outbreaks of COVID-19: Prospective observational cohort study, England 2020. Lancet Reg Health Eur. 2021;3: 100038. | CrossRef | Link |
  29. Bobrovitz N, Arora RK, Cao C, Boucher E, Liu M, Donnici C, et al. Global seroprevalence of SARS-CoV-2 antibodies: A systematic review and meta-analysis.PLoS One. 2021;16: 1–21. | CrossRef |
  30. Barros ENC de, Valle AP do, Braga PE, Viscondi JYK, Fonseca ARB da, Vanni T, et al. COVID-19 in long-term care facilities in Brazil: serological survey in a post-outbreak setting. Rev Inst Med Trop Sao Paulo. 2021;63 | CrossRef |
  31. Belmin J, Georges S, Franke F, Daniau C, Cochet A, Durand C, et al. Coronavirus Disease 2019 in French Residential Care Facilities: A Nationwide Study. J Am Med Dir Assoc. 2021;22: 1142–1145. | CrossRef |
  32. Bonafede MM, Kalsekar A, Pawaskar M, Ruiz KM, Torres AM, Kelly KR, et al. Insulin use and persistence in patients with type 2 diabetes adding mealtime insulin to a basal regimen: a retrospective database analysis. BMC Endocr Disord. 2011;11. | CrossRef | Link |
  33. World Health Organization (WHO). Infection Prevention and Control guidance for Long-Term Care Facilities in the context of COVID-19. Guidance of World Health Interim Organization; 2020. | Link |
  34. Arons MM, Hatfield KM, Reddy SC, Kimball A, James A, Jacobs JR, et al. Presymptomatic SARS-CoV-2 Infections and Transmission in a Skilled Nursing Facility. N Engl J Med. 2020;382: 2081–2090. | CrossRef |
  35. Servicio Nacional del Adulto Mayor (SENAMA). Estudio de actualización del catastro de Establecimientos de Larga Estadía (ELEAM) de las regiones de Tarapacá. Antofagasta, Atacama, Bernardo O’higgins, Maule, Biobío, Araucanía, Los Lagos, Aysén Del General Carlos Ibáñez del Campo, Magallanes y Antártic; 2013. | Link |
  36. Heneghan C, Brassey J, Jefferson T. COVID-19: What proportion are asymptomatic? [Internet]. The Centre for Evidence Based Medicine. Evidence Service to support the COVID-19 response. 2020. | Link |
  37. Vial PA, González C, Icaza G, Ramirez-Santana M, Quezada-Gaete R, Nuñez-Franz L, et al. Seroprevalence, Spatial Distribution, and Social Determinants of SARS-CoV-2 in Three Urban Centers of Chile. SSRN Journal. 2021. | CrossRef | Link |
  38. Zervou FN, Louie P, Stachel A, Zacharioudakis IM, Ortiz-Mendez Y, Thomas K, et al. SARS-CoV-2 antibodies: IgA correlates with severity of disease in early COVID-19 infection. J Med Virol. 2021;93: 5409–5415. | CrossRef | Link |
  39. Seow J, Graham C, Merrick B, Acors S, Pickering S, Steel KJA, et al. Longitudinal observation and decline of neutralizing antibody responses in the three months following SARS-CoV-2 infection in humans. Nat Microbiol. 2020;5: 1598–1607. | CrossRef |
  40. Iruretagoyena M, Vial MR, Spencer-Sandino M, Gaete P, Peters A, Delgado I, et al. Longitudinal assessment of SARS-CoV-2 IgG seroconversionamong front-line healthcare workers during the first wave of the Covid-19 pandemic at a tertiary-care hospital in Chile. BMC Infect Dis. 2021;21. | CrossRef |
  41. Fulop T, Pawelec G, Castle S, Loeb M. Immunosenescence and vaccination in nursing home residents. Clin Infect Dis. 2009;48: 443–8. | CrossRef | Link |
  42. Pegoraro M, Militello V, Salvagno GL, Gaino S, Bassi A, Caloi C, et al. Evaluation of three immunochromatographic tests in COVID-19 serologic diagnosis and their clinical usefulness. Eur J Clin Microbiol Infect Dis. 2021;40: 897–900. | CrossRef |
  43. Chidambaram P, Garfield R. Kaiser Family Foundation. 2021. | Link |
  44. Wiersinga WJ, Rhodes A, Cheng AC, Peacock SJ, Prescott HC. Pathophysiology, Transmission, Diagnosis, and Treatment of Coronavirus Disease 2019 (COVID-19): A Review. JAMA. 2020;324: 782–793. | CrossRef | Link |
  45. Onder G, Rezza G, Brusaferro S. Case-Fatality Rate and Characteristics of Patients Dying in Relation to COVID-19 in Italy. JAMA. 2020;323: 1775–1776. | CrossRef |
Vellas C, Delobel P, de Souto Barreto P, Izopet J. COVID-19, Virology and Geroscience: A Perspective. J Nutr Health Aging. 2020;24: 685–691. | CrossRef | Link |

Denis M, Vandeweerd V, Verbeeke R, Laudisoit A, Reid T, Hobbs E, et al. Covipendium: Information available to support the development of medical countermeasures and interventions against COVID-19. Transdisciplinary Insights. 2020;4: 1–296. | CrossRef | Link |

Fischer RJ, Morris KK, McCorkel LA, Case SM, Pham HH, et al. An Ounce of Prevention: Reducing the Risk of COVID-19 Transmission in Long-Term Care Facilities. J Geriatr Med Gerontol. 2020;6. | CrossRef | Link |

Battisti NML, Mislang AR, Cooper L, O’Donovan A, Audisio RA, Cheung K-L, et al. Adapting care for older cancer patients during the COVID-19 pandemic: Recommendations from the International Society of Geriatric Oncology (SIOG) COVID-19 Working Group. J Geriatr Oncol. 2020;11: 1190–1198. | CrossRef |

Sociedad Española de Médicos de Atención Primaria (Semergen). Síntomas atípicos de Covid-19 en pacientes crónicos mayores. 6 Jul 2020. | Link |

Suárez-González A, Livingston G, Cahill S, Hennelly N, Dawson WD, Weidner W, et al. Impact and mortality of COVID-19 on people living with dementia: cross-country report. 5 Jul 2020. | Link |

Centers for Disease Control and Prevention (CDC). Responding to coronavirus (COVID-19) in nursing homes. | Link |

International Long-term Care Policy Network (ILPN) and CarInternational Long-term Care Policy Network (ILPN) and Care Policy and Evaluation Centre (CPEC) at the London School of Economics and Political Science (LSE). International reports on COVID-19 and Long-Term Care. Resources to support community and institutional Long-Term Care responses to COVID-19; 2021. | Link |

Vena A, Berruti M, Adessi A, Blumetti P, Brignole M, Colognato R, et al. Prevalence of Antibodies to SARS-CoV-2 in Italian Adults and Associated Risk Factors. J Clin Med. 2020;9. | CrossRef | Link |

Shi SM, Bakaev I, Chen H, Travison TG, Berry SD. Risk Factors, Presentation, and Course of Coronavirus Disease 2019 in a Large, Academic Long-Term Care Facility. J Am Med Dir Assoc. 2020;21: 1378–1383. | CrossRef |

Byrd W, Salcher-Konrad M, Smith S, Comas-Herrera A. What Long-Term Care Interventions and Policy Measures Have Been Studied During the Covid-19 Pandemic? Findings from a Rapid Mapping Review of the Scientific Evidence Published During 2020. JLTC. 2021;0: 423. | CrossRef | Link |

Wachholz PA, Jacinto AF, Melo RC de, Dinamarca-Montecinos JL, Boas PJFV. Challenges in long-term care facilities for older adults in Hispanic American countries. Geriatr Gerontol Aging.2020;14: 259–266. | CrossRef | Link |

Kimball A, Hatfield KM, Arons M, James A, Taylor J, Spicer K, et al. Asymptomatic and Presymptomatic SARS-CoV- 2 Infections in Residents of a Long-Term Care Skilled Nursing Facility - King County, Washington, March 2020. MMWR Morb Mortal Wkly Rep. 2020;69: 377–381. | CrossRef | Link |

Graham NSN, Junghans C, Downes R, Sendall C, Lai H, McKirdy A, et al. SARS-CoV-2 infection, clinical features and outcome of COVID-19 in United Kingdom nursing homes. J Infect. 2020;81: 411–419. | CrossRef | Link |

Roxby AC, Greninger AL, Hatfield KM, Lynch JB, Dellit TH, James A, et al. Detection of SARS-COV-2 Among Residents and Staff Members of an Independent and Assisted Living Community for Older Adults - Seattle, Washington, 2020. MMWR Morb Mortal Wkly Rep. 2020;69: 416–418. | CrossRef |

Ochieng N, Chidambaram P, Garfield R, Neuman T. 2021; 1–20. | Link |

Organización Mundial de la Salud (OMS). Protocolo para estudios seroepidemiológicos poblacionales sobre la COVID-19, con estratificación por edades. 5 Jul 2020. | Link |

Centers for Disease Control and Prevention. COVID-19 Serology Surveillance Strategy. COVID-19 Serology Surveillance. Data & Surveillance; 6 Jul 2021. | Link |

Departamento de Estadísticas e Información de Salud. Informe semanal de defunciones por COVID-19. 2021. | Link |

Departamento de Epidemiología Ministerio de Salud del Gobierno de Chile. Informe Epidemiológico No 128. Enfermedad por SARS-CoV-2. Chile. 2021. | Link |

Massad C, Herrera F. Condiciones de vida de las personas mayores al interior de establecimientos de larga estadía para adultos mayores de SENAMA. 2017. | Link |

Servicio Nacional del Adulto Mayor. Protocolo para centros residenciales de personas mayores para la prevención y atención del COVID-19. Santiago; 2020. | Link |

Innovita Beijing and Innovita Tangshan. INNOVITA 2019-nCoV IgM/IgG Combo Test. 2019. | Link |

Departamento de Epidemiología del Ministerio de Salud del Gobierno de Chile. Informe Epidemiológico N°68. Enfermedad por SARS-CoV-2 (COVID-19). 2020. | Link |

Sargento ESG. Epitools Epidemiological Calculators. usvet. 2018. | Link |

Vial P, González C, Icaza G, Ramirez-Santana M, Quezada-Gaete R, Núñez-Franz L, et al. Seroprevalence, spatial distribution, and social determinants of SARS-CoV-2 in three urban centers of Chile. BMC Infect Dis. 2022;22. | CrossRef | Link |

Ministerio de Salud de Chile. Situación Nacional de COVID-19 en Chile. 2021. | Link |

Jeffery-Smith A, Dun-Campbell K, Janarthanan R, Fok J, Crawley-Boevey E, Vusirikala A, et al. Infection and transmission of SARS-CoV-2 in London care homes reporting no cases or outbreaks of COVID-19: Prospective observational cohort study, England 2020. Lancet Reg Health Eur. 2021;3: 100038. | CrossRef | Link |

Bobrovitz N, Arora RK, Cao C, Boucher E, Liu M, Donnici C, et al. Global seroprevalence of SARS-CoV-2 antibodies: A systematic review and meta-analysis.PLoS One. 2021;16: 1–21. | CrossRef |

Barros ENC de, Valle AP do, Braga PE, Viscondi JYK, Fonseca ARB da, Vanni T, et al. COVID-19 in long-term care facilities in Brazil: serological survey in a post-outbreak setting. Rev Inst Med Trop Sao Paulo. 2021;63 | CrossRef |

Belmin J, Georges S, Franke F, Daniau C, Cochet A, Durand C, et al. Coronavirus Disease 2019 in French Residential Care Facilities: A Nationwide Study. J Am Med Dir Assoc. 2021;22: 1142–1145. | CrossRef |

Bonafede MM, Kalsekar A, Pawaskar M, Ruiz KM, Torres AM, Kelly KR, et al. Insulin use and persistence in patients with type 2 diabetes adding mealtime insulin to a basal regimen: a retrospective database analysis. BMC Endocr Disord. 2011;11. | CrossRef | Link |

World Health Organization (WHO). Infection Prevention and Control guidance for Long-Term Care Facilities in the context of COVID-19. Guidance of World Health Interim Organization; 2020. | Link |

Arons MM, Hatfield KM, Reddy SC, Kimball A, James A, Jacobs JR, et al. Presymptomatic SARS-CoV-2 Infections and Transmission in a Skilled Nursing Facility. N Engl J Med. 2020;382: 2081–2090. | CrossRef |

Servicio Nacional del Adulto Mayor (SENAMA). Estudio de actualización del catastro de Establecimientos de Larga Estadía (ELEAM) de las regiones de Tarapacá. Antofagasta, Atacama, Bernardo O’higgins, Maule, Biobío, Araucanía, Los Lagos, Aysén Del General Carlos Ibáñez del Campo, Magallanes y Antártic; 2013. | Link |

Heneghan C, Brassey J, Jefferson T. COVID-19: What proportion are asymptomatic? [Internet]. The Centre for Evidence Based Medicine. Evidence Service to support the COVID-19 response. 2020. | Link |

Vial PA, González C, Icaza G, Ramirez-Santana M, Quezada-Gaete R, Nuñez-Franz L, et al. Seroprevalence, Spatial Distribution, and Social Determinants of SARS-CoV-2 in Three Urban Centers of Chile. SSRN Journal. 2021. | CrossRef | Link |

Zervou FN, Louie P, Stachel A, Zacharioudakis IM, Ortiz-Mendez Y, Thomas K, et al. SARS-CoV-2 antibodies: IgA correlates with severity of disease in early COVID-19 infection. J Med Virol. 2021;93: 5409–5415. | CrossRef | Link |

Seow J, Graham C, Merrick B, Acors S, Pickering S, Steel KJA, et al. Longitudinal observation and decline of neutralizing antibody responses in the three months following SARS-CoV-2 infection in humans. Nat Microbiol. 2020;5: 1598–1607. | CrossRef |

Iruretagoyena M, Vial MR, Spencer-Sandino M, Gaete P, Peters A, Delgado I, et al. Longitudinal assessment of SARS-CoV-2 IgG seroconversionamong front-line healthcare workers during the first wave of the Covid-19 pandemic at a tertiary-care hospital in Chile. BMC Infect Dis. 2021;21. | CrossRef |

Fulop T, Pawelec G, Castle S, Loeb M. Immunosenescence and vaccination in nursing home residents. Clin Infect Dis. 2009;48: 443–8. | CrossRef | Link |

Pegoraro M, Militello V, Salvagno GL, Gaino S, Bassi A, Caloi C, et al. Evaluation of three immunochromatographic tests in COVID-19 serologic diagnosis and their clinical usefulness. Eur J Clin Microbiol Infect Dis. 2021;40: 897–900. | CrossRef |

Chidambaram P, Garfield R. Kaiser Family Foundation. 2021. | Link |

Wiersinga WJ, Rhodes A, Cheng AC, Peacock SJ, Prescott HC. Pathophysiology, Transmission, Diagnosis, and Treatment of Coronavirus Disease 2019 (COVID-19): A Review. JAMA. 2020;324: 782–793. | CrossRef | Link |

Onder G, Rezza G, Brusaferro S. Case-Fatality Rate and Characteristics of Patients Dying in Relation to COVID-19 in Italy. JAMA. 2020;323: 1775–1776. | CrossRef |