Performance verification of the Abbott SARS-CoV-2 test for qualitative detection of IgG in Cali, Colombia.

BACKGROUND: Adequate testing is critically important for control of the SARS-CoV-2 pandemic. Antibody testing is an option for case management and epidemiologic studies, with high specificity and variable sensitivity. However, characteristics of local populations may affect performance of these tests. For this reason, the National Institute of Health (INS) and regulatory agencies in Colombia require verification of diagnostic accuracy of tests introduced to the Colombian market. METHODS: We conducted a validation study of the Abbott SARS-CoV-2 test for qualitative detection of IgG using the Abbott Architect i2000SR. Participants and retrospective samples were included from patients with suspected SARS-CoV-2 infection, age ≥18 years, and ≥8 days elapsed since initiation of symptoms. Pre-pandemic plasma samples (taken before October 2019) were used as controls. We estimated the sensitivity, specificity and agreement (kappa) of the Abbott IgG test compared to the gold standard (RT-PCR). RESULTS: The overall sensitivity was 83.1% (95% CI: 75.4-100). Sensitivity among patients with ≥14 days since the start of symptoms was 85.7%, reaching 88% in samples collected from patients with COVID-19 symptoms onset >60 days. Specificity was 100% and the kappa index of agreement was 0.804 (95% CI: 0.642-0.965). CONCLUSIONS: Our findings show high sensitivity and specificity of the Abbott IgG test in a Colombian population, which meet the criteria set by the Colombian INS to aid in the diagnosis of COVID-19. Data from our patient groups also suggest that IgG response is detectable in a high proportion of individuals (88.1%) during the first two months following onset of symptoms.

Assessment of therapeutic response of Plasmodium vivax and Plasmodium falciparum to chloroquine in a Malaria transmission free area in Colombia.

In order to determine the frequency of therapeutic failures to chloroquine (CQ) in patients with malaria due to either Plasmodium falciparum or P. vivax, and to explore the usefulness of a malaria-free city as a sentinel site to monitor the emergence of drug resistance, 53 patients (44 infected with P. vivax and 9 with P. falciparum) were evaluated at the Laboratory of Parasitology, Universidad del Valle in Cali, Colombia. Patients received 25 mg/kg of CQ divided in three doses over 48 h; they were followed during 28 days according to WHO/PAHO protocols. While therapeutic failures to CQ in the P. vivax group were not detected, the proportion of therapeutic failures in the P. falciparum group was high (78%) and consistent with the reports from endemic areas in Colombia. The diverse origin of cases presenting therapeutic failure confirmed that P. falciparum resistant to CQ is widespread in Colombia, and further supports the change in the national antimalarial drug scheme. Monitoring of drug resistance in malaria free areas would be useful to identify sites requiring efficacy evaluation, and in some situations could be the most appropriate alternative to collect information from endemic areas where therapeutic efficacy studies are not feasible.

Assessment of Therapeutic Response of Plasmodium vivax and Plasmodium falciparum to Chloroquine in a Malaria Transmission Free Area in Colombia

In order to determine the frequency of therapeutic failures to chloroquine (CQ) in patients with malaria due to either Plasmodium falciparum or P. vivax, and to explore the usefulness of a malaria-free city as a sentinel site to monitor the emergence of drug resistance, 53 patients (44 infected with P. vivax and 9 with P. falciparum) were evaluated at the Laboratory of Parasitology, Universidad del Valle in Cali, Colombia. Patients received 25 mg/kg of CQ divided in three doses over 48 h; they were followed during 28 days according to WHO/PAHO protocols. While therapeutic failures to CQ in the P. vivax group were not detected, the proportion of therapeutic failures in the P. falciparum group was high (78 percent) and consistent with the reports from endemic areas in Colombia. The diverse origin of cases presenting therapeutic failure confirmed that P. falciparum resistant to CQ is widespread in Colombia, and further supports the change in the national antimalarial drug scheme. Monitoring of drug resistance in malaria free areas would be useful to identify sites requiring efficacy evaluation, and in some situations could be the most appropriate alternative to collect information from endemic areas where therapeutic efficacy studies are not feasible