Population-Based COVID-19 Screening in Mexico: Assessment of Symptoms and Their Weighting in Predicting SARS-CoV-2 Infection.

Background and Objectives: Sentinel surveillance in the early stage of the COVID-19 pandemic in Mexico represented a significant cost reduction and was useful in estimating the population infected with SARS-CoV-2. However, it also implied that many patients were not screened and therefore had no accurate diagnosis. In this study, we carried out a population-based SARS-CoV-2 screening in Mexico to evaluate the COVID-19-related symptoms and their weighting in predicting SARS-CoV-2 infection. We also discuss this data in the context of the operational definition of suspected cases of COVID-19 established by the Mexican Health Authority's consensus. Materials and Methods: One thousand two hundred seventy-nine subjects were included. They were screened for SARS-CoV-2 using RT-PCR. The weighting of COVID-19 symptoms in predicting SARS-CoV-2 infection was evaluated statistically. Results: Three hundred and twenty-five patients were positive for SARS-CoV-2 and 954 were negative. Fever, asthenia, dysgeusia, and oxygen saturation predicted SARS-CoV-2 infection (odds ratios ranged from 1.74 to 4.98; p < 0.05). The percentage of asymptomatic COVID-19 patients was 36% and only 38.15% met the Mexican operational definition. Cq-values for the gene N of SARS-CoV-2 were significantly higher in asymptomatic subjects than in the groups of COVID-19 patients with neurological, respiratory, and/or musculoskeletal manifestations (p < 0.05). Conclusions: Dysgeusia, fever, and asthenia increased the odds of a positive result for COVID-19 1.74-4.98-fold among the study population. Patients with neurological, respiratory, and/or musculoskeletal manifestations had higher viral loads at COVID-19 diagnosis than those observed in asymptomatic patients. A high percentage of the participants in the study (61.85%) did not meet the operational definition for a suspected case of COVID-19 established by the Mexican Health Authority's consensus, representing a high percentage of the population that could have remained without a COVID-19 diagnosis, so becoming a potential source of virus spread.

Spontaneous abortion is preceded by an altered serum concentration of matrix metalloproteinases.

Objective: To evaluate the usefulness of the serum concentration of nine matrix metalloproteinases (MMPs) as biomarkers of spontaneous abortion.Methods: A retrospective nested cohort case-control study was carried out in Zacatecas, Mexico. MMP-1-3, MMP-7-10, and MMP-12-13 were analyzed in serum from women who had spontaneous abortion of unknown causes (n = 7), who suffered abortions attributed to urinary tract infection (n = 7) and from those with healthy pregnancies without complications (controls; n = 20). Protein profiles were determined between 11 and 13 weeks of gestation (GW) using the Bio-Plex Pro Human MMP Panel. Differences in serum MMP concentrations between the study groups and their correlation with clinical findings were evaluated statistically.Results: There were differences in serum concentrations of MMP-9 between groups of spontaneous abortion of unknown cause (13.2 ± 7.5 ng/µL), abortion attributed to urinary tract infection (11.6 ± 5.8 ng/µL) and the controls (11.8 ± 16.5 ng/µL) (p = .022). Compared with controls, higher serum concentrations of MMP-8, MMP-9, and MMP-10 were observed in the group of spontaneous abortions of unknown causes (p value < .05). A negative correlation between MMP-8 and MMP-9 and urine density was also identified (r = -0.949, p value = .0167; and r = -0.947, p = .0167).Conclusions: Elevated serum concentrations of MMP-8, MMP-9, and MMP-10 were associated and preceded by the appearance of spontaneous interruption of pregnancy of unknown causes. Our results support the hypothesis that altered MMP modulation may be related with the pathogenesis of spontaneous abortion.