TITLE
Performance of a point of care test for detecting IgM and IgG antibodies against SARS-CoV-2 and
seroprevalence in blood donors and health care workers in Panama.
SHORT TITLE
SARS-CoV-2 rapid test performance and seroprevalence in Panama
AUTHORS
Alcibiades Villarreal
1,*
, Giselle Rangel
1,*
, Xu Zhang
2,3,4,*
, Digna Wong
1
, Gabrielle Britton
1
,
Patricia L.
Fernandez
1
, Ambar Pérez
1
, Diana Oviedo
1,12
, Carlos Restrepo
1
, María B. Carreirra
1
, Dilcia Sambrano
1
,
Gilberto A. Eskildsen
1,9
, Carolina De La Guardia
1
, Yamitzel Zaldivar
5
, Danilo Franco
6
, Sandra López-
Vergès
6
, Dexi Zhang
2,3,4
, Fangjing Fan
2,3,4
, Baojun Wang
7
, Xavier Sáez-Llorens
8
, Rodrigo DeAntonio
8
,
Ivonne Torres-Atencio
9
, Fernando Diaz Subía
10
, Eduardo Ortega-Barria
11
, Rao Kosagisharaf
1
, Ricardo
Lleonart
1
, Chong Li
2,3,4,#
, Amador Goodridge
1,#,
and COVID-19 serology collaborator group.
AUTHOR AFFILIATIONS
1
Centro de Biología Celular y Molecular de las Enfermedades, Instituto de Investigaciones Científicas y
Servicios de Alta Tecnología (INDICASAT-AIP), City of Knowledge, PANAMA.
2
Institute of Biophysics, Chinese Academy of Sciences, Beijing, CHINA.
3
Beijing Zhongke Jianlan Biotechnology Co., Ltd.; Beijing, CHINA.
4
Zhongke Jianlan International Medical Research Institute, Melbourne, Victoria, AUSTRALIA.
5
Department of Research in Surveillance and Biologic risk 3, Gorgas Memorial Institute of Health
Studies, Panama, PANAMA.
6
Department of Research in Virology and Biotechnology, Gorgas Memorial Institute of Health Studies,
Panama, PANAMA.
7
Beijing Kewei Clinical Diagnostic Reagent Inc., Beijing, CHINA.
8
CEVAXIN, Centro de Vacunación e Investigación Panama Clinic, PANAMA.
9
Facultad de Medicina, Universidad de Panamá, Panama City, PANAMA.
. CC-BY 4.0 International licenseIt is made available under a
is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.(which was not certified by peer review)preprint
The copyright holder for thisthis version posted December 10, 2020. ; https://doi.org/10.1101/2020.09.25.20201459doi: medRxiv preprint
NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.
10
Pacifica Salud, Panama City, PANAMA.
11
GlaxoSmithKline Vaccines, City of Knowledge, PANAMA.
12
Escuela de Psicología, Universidad Santa María La Antigua, PANAMA
* Contributed equally to this work as co-first authors.
#CORRESPONDING AUTHORS: agoodridge@indicasat.org.pa
; Phone (+507) 517-0722, Postal
Address: Building 208, City of Knowledge, Panama; & lichong@ibp.ac.cn; Phone (86010) 6488-7989,
Address: No. 15 Datun Road, Institute of Biophysics, Chinese Academy of Sciences, Chaoyang
District, Beijing, CHINA.
COAUTHORS OF COVID-19 SEROLOGY COLLABORATOR GROUP:
Julio Flores-Cuadra
1
, Jean-Paul Carrera
5
, Aron Benzadon
11
, Laiss Mudarra
12
, Lineth López
13
, Walter
Valverde
12
, Isabel Blanco
13
, Nicolás Hurtado
14
, Neyla Rivas
14
, Julio Jurado
14
, Aixa Carvallo
15
, Juan
Rodriguez
15
, Yaseikiry Perez
15
, Johanna Morris
15
, Odemaris Luque
16
, David Cortez
17
AFILIATIONS OF COVID-19 SEROLOGY COLLABORATOR GROUP
1
Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT-AIP), City of
Knowledge, PANAMA.
6
Department of Research in Virology and Biotechnology, Gorgas Memorial Institute of Health Studies,
Panama, PANAMA.
11
Centro Medico Paitilla, Panama City, PANAMA.
12
Complejo Hospitalario Metropolitano Dr. Arnulfo Arias Madrid, Caja de Seguro Social, Panama City,
PANAMA.
13
Pacifica Salud, Panama City, PANAMA.
14
Compleo Hospitalario Manuel Amador Guerrero, Caja de Seguro Social, Colón City, PANAMÁ.
15
Bancos de Sangre, Caja de Seguro Social, PANAMA.
16
Programa de Salud de Adultos, Ministerio de Salud, Colón, PANAMA.
. CC-BY 4.0 International licenseIt is made available under a
is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.(which was not certified by peer review)preprint
The copyright holder for thisthis version posted December 10, 2020. ; https://doi.org/10.1101/2020.09.25.20201459doi: medRxiv preprint
17
Dirección Nacional de Laboratorios Clínicos, Ministerio de Salud, Panama City, PANAMA.
ABSTRACT
Novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of the
ongoing coronavirus disease 2019 (COVID-19) pandemic, which has reached 28 million cases
worldwide in eight months. The serological detection of antibodies against the virus will play a pivotal
role in complementing molecular tests to improve diagnostic accuracy, contact tracing, vaccine efficacy
testing and seroprevalence surveillance. Here, we aimed first to evaluate a lateral flow assay’s ability to
identify specific IgM and IgG antibodies against SARS-CoV-2 and second, to report the seroprevalence
of these antibodies among health care workers and healthy volunteer blood donors in Panama. We
recruited study participants between April 30
th
and July 7
th
, 2020. For the test validation and
performance evaluation, we analyzed serum samples from participants with clinical symptoms and
confirmed positive RT-PCR for SARS-CoV-2, and a set of pre-pandemic serum samples. We used two
by two table analysis to determine the test sensitivity and specificity as well as the kappa agreement
value with a 95% confidence interval. Then, we used the lateral flow assay to determine
seroprevalence among serum samples from COVID-19 patients, potentially exposed health care
workers, and healthy volunteer donors. Our results show this assay reached a positive percent
agreement of 97.2% (95% CI 84.2-100.0%) for detecting both IgM and IgG. The assay showed a
kappa of 0.898 (95%CI 0.811- 0.985) and 0.918 (95% CI 0.839-0.997) for IgM and IgG, respectively.
The evaluation of serum samples from hospitalized COVID-19 patients indicates a correlation between
test sensitivity and the number of days since symptom onset; the highest positive percent agreement
(87% (95% CI 67.0-96.3%)) was observed at
≥
15 days post-symptom onset. We found an overall
antibody seroprevalence of 11.6% (95% CI 8.5-15.8%) among both health care workers and healthy
blood donors. Our findings suggest this lateral flow assay could contribute significantly to implementing
seroprevalence testing in locations with active community transmission of SARS-CoV-2.
KEYWORDS: COVID-19, serology, lateral flow chromatographic immunoassay, biomarker, screening
test.
. CC-BY 4.0 International licenseIt is made available under a
is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.(which was not certified by peer review)preprint
The copyright holder for thisthis version posted December 10, 2020. ; https://doi.org/10.1101/2020.09.25.20201459doi: medRxiv preprint
INTRODUCTION
Coronavirus disease 2019 (COVID-19) is a viral pneumonia and multi-systemic disease caused
by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which first appeared in Wuhan,
China in December 2019 [1, 2]. Since then, the virus has spread rapidly with an explosive increase in
cases across the globe. As of 12 September 2020, there have been 28,329,790 confirmed cases of
COVID-19, including 911,877 deaths reported to WHO [3]. According to the Pan American Health
Organization (PAHO), by August, Panama had a rate of 1,618 infected persons per 100,000 inhabitants
[4, 5], placing it as the country with the second highest rate of infection in the Americas. This high rate
is in part related to the fact that Panama is among the countries in the region that have conducted the
highest number of tests. More than 250,000 molecular tests have been conducted since early March,
and daily positivity rates have consistently been in the 30% range; there have been more than 100,000
confirmed cases. In Panama, the majority of reported cases (93.2%) demonstrate mild symptoms, while
6.8% have required hospitalization. To date, there have been 2,140 deaths and over 72,000 patients
have recovered [6].
Until a vaccine becomes available, most countries’ containment efforts have relied heavily on
non-pharmacological interventions to mitigate and suppress the disease. These include, but are not
limited to, movement restrictions and reduced individual contact to decrease community transmission
[7]. As a result, the COVID-19 pandemic, in addition to being a public health emergency, has become a
financial and sociopolitical crisis. Consequently, public health strategies are urgently needed in order to
ease lock-down restrictions [8]. One of the most effective strategies includes prompt and accurate
diagnosis. The development of a diagnostic test that can be scaled-up to allow for mass screening
among specific high-risk groups, such as health care workers (HCW), remains a key step [9, 10]. Such
a test would aid with diagnosis, contact tracing, and vaccine evaluation, while also allowing the release
of individuals from quarantine, as well as serological surveillance at the local, regional, and national
level [11].
More than 150 diagnostics tests have been developed since the beginning of the COVID-19
pandemic [12]. The most-used platforms are enzyme-linked immunosorbent assays (ELISA) and rapid
lateral flow immunoassays (LFIA) [13]. In general, serological tests based on an LFIA platform are cost-
and time-efficient, do not require sophisticated equipment or highly trained personnel, and can be used
to assess population exposure. In addition, LFIA platforms have generated substantial interest because
they are cheaper to manufacture, store, and distribute, and easier to implement as a point-of-care test.
Unfortunately, some countries have rushed into large-scale deployment of rapid tests but have found
that the clinical sensitivities are low and of poor value due to inadequate performance assessment [14,
. CC-BY 4.0 International licenseIt is made available under a
is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.(which was not certified by peer review)preprint
The copyright holder for thisthis version posted December 10, 2020. ; https://doi.org/10.1101/2020.09.25.20201459doi: medRxiv preprint
15]. The performance of rapid tests provided by manufacturers might show variations. Consequently,
rapid tests should be rigorously validated in a large target population before being used as a stand-
alone screening test [16].
Our study aimed to evaluate the performance of an LFIA for the detection of IgM and IgG anti-
SARS antibodies in COVID-19-positive individuals[17]. First, we determined the test performance of an
LFIA as a rapid serology test, using a standard panel of sera from COVID-19 patients and pre-
pandemic donors. Second, we conducted a field evaluation of the LFIA test to determine the
seroprevalence of anti-SARS-CoV-2 antibodies among healthy blood donors (HD) and health care
workers (HCW). We found this test to be suitable for conducting seroprevalence studies, assessing
population exposure to the virus, and for evaluating the effects of lock-down flexibilization strategies.
MATERIALS AND METHODS
Lateral flow immunoassay overview
We obtained an LFIA test developed by Dr. Chong Li’s group from Institute of Biophysics, Chinese
Academy of Science. The qualitative test (referred to as CAST – Chinese Academy of Science Test,
from this point) detects and is capable of differentiating between specific IgM and IgG antibodies
against SARS-CoV-2. The CAST uses a colored conjugate pad containing a recombinant SARS-CoV-2
nucleocapsid protein conjugated with colloid gold as the antigen. The CAST manufacturer’s calculated
analytical sensitivity and specificity for both IgM and IgG anti-SARS-CoV-2 antibodies at development
were 87.01% and 98.89%, respectively. During development in China, no cross-reactivity was reported
with specimens from patients infected with Human Immunodeficiency Virus (HIV), Hepatitis A Virus
(HAV), Hepatitis B soluble Antigen, Hepatitis C Virus, Treponema pallidum, Human T Lymphocyte Virus
(HTLV), Cytomegalovirus, Influenza Virus type A and B, Respiratory Syncytial Virus, Human Papilloma
Virus, Chlamydophila pneumoniae, Legionella pneumophila, Mycoplasma pneumoniae, or Human
Parainfluenza viruses, as well as other coronaviruses. Moreover, no cross-reactivity or interference was
observed with endogenous substances, including common serum components, such as lipids,
hemoglobin, bilirubin, albumin, uric acid, and glucose, or other common biological analytes, such as
acetaminophen, acetoacetic acid, benzoylecgonine, caffeine, EDTA, ethanol, gentisic acid,
β
-
Hydroxybutyrate, methanol, phenothiazine, phenylpropanolamine, and salicylic acid.
. CC-BY 4.0 International licenseIt is made available under a
is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.(which was not certified by peer review)preprint
The copyright holder for thisthis version posted December 10, 2020. ; https://doi.org/10.1101/2020.09.25.20201459doi: medRxiv preprint
