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Test positivity - evaluation of a new metric to assess epidemic dispersal mediated by non-symptomatic cases.

ABSTRACT: Epidemic control may be hampered when the percentage of asymptomatic cases is high. To estimate whether test positivity may assist in policy-making, it was explored in the first 60 to 90 epidemic days in six Latin American countries that reported their first COVID-19 case between February and March, 2020: Argentina, Bolivia, Chile, Cuba, Mexico, and Uruguay. Test positivity (TP) is the percentage of test-positive individuals recorded on a given day out of all individuals tested on the same day. The epidemic data of the country infected last (Uruguay) was first analyzed to evaluate TP as well as: (i) the daily ratio of secondary over primary infections (apparent reproductive ratio or ARR); (ii) tests conducted per million inhabitants (TPMI), (iii) the temporal data on the number of active cases (all test-positive cases minus deaths and recovered patients), and (iv) that of recovered patients. Later, significant patterns identified in the first step were assessed in the six countries. The Uruguayan data indicated that (i) TP was positively correlated with the ARR (r=.92, p<0.01); (ii) TP informed more than the ARR: while major data departures revealed by the ARR were also detected by TP, TP exhibited patterns not shown by ARR; and (iii) three temporal stages were observed, which differed from one another in both TP and TPMI medians (P<0.01) and, together, revealed a negative relationships between TPMI and TP. The six Latin American countries showed that TP was positively correlated with deaths/million inhabitants or DMI (r=.62, p<0.01). The temporal analysis of policies revealed four patterns: (1) low testing and high DMI, (2) high testing and low DMI; (3) an intermediate pattern, and (4) high testing and high DMI (where isolation was not pursued). Findings support the hypothesis that test positivity may inform as much as, if not more than classic metrics, such as the TPMI. If complemented with high-resolution geographical data, these indicators could inform policy-makers when and where epidemic control measures are or are not successful. .

SUBMITTER: Fasina FO

PROVIDER: S-EPMC8144156 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The coronavirus disease 2019 (COVID-19) cases could be symptomatic or asymptomatic. We (1) characterized and analyzed data collected from the first cohort of reverse transcriptase polymerase chain reaction (RT-PCR)-confirmed COVID-19 cases reported in the Emirate of Abu Dhabi, United Arab Emirates, according to the symptomatic state, and (2) identified factors associated with the symptomatic state. The association between the symptomatic state and testing positive in three subsequent RT-PCR testing rounds was also quantified. Between February 28 and April 8, 2020, 1,249 cases were reported. Sociodemographic characteristics, working status, travel history, and chronic comorbidities of 791 cases were analyzed according to the symptomatic state (symptomatic or asymptomatic). After the first confirmatory test, the results of three subsequent tests were analyzed. The mean age of the 791 cases was 35.6 ± 12.7 years (range: 1-81). Nearly 57.0% of cases were symptomatic. The two most frequent symptoms were fever (58.0%) and cough (41.0%). Symptomatic cases (mean age 36.3 ± 12.6 years) were significantly older than asymptomatic cases (mean age 34.5 ± 12.7 years). Compared with nonworking populations, working in public places (adjusted odds ratio (aOR), 1.76, 95% confidence interval (95% CI): 1.11-2.80), healthcare settings (aOR, 2.09, 95% CI: 1.01-4.31), or in the aviation and tourism sectors (aOR, 2.24, 95% CI: 1.14-4.40) was independently associated with the symptomatic state. Reporting at least one chronic comorbidity was also associated with symptomatic cases (aOR, 1.76, 95% CI: 1.03-3.01). Compared with asymptomatic cases, symptomatic cases had a prolonged duration of viral shedding and consistent odds of ?2 positive COVID-19 tests result out of the three subsequent testing rounds. A substantial proportion of the diagnosed COVID-19 cases in the Emirate of Abu Dhabi were asymptomatic. Quarantining asymptomatic cases, implementing prevention measures, and raising awareness among populations working in high-risk settings are warranted.

Project description:BackgroundCorona 2 virus (SARS-CoV-2) is known as the causative agent of COVID-19 disease; the World Health Organization (WHO) declared it an epidemic on March 11, 2020. The Joint Guidelines of the Centers for Disease Control and Prevention (CDC) and the WHO including social distancing, the use of face masks, emphasis on hand washing, quarantine, and using diagnosis tests have been used widely, but the value of diagnostic interventions to prevent the transmission of SARS-CoV-2 is unclear. We compared the economic evaluation of different laboratory diagnostic interventions with each other and also with implementing the conservative CDC & WHO guidelines.Material and methodsElectronic searches were conducted on PubMed, Embase, Science Direct, Scopus, Cochrane Library, Web of Knowledge, NHSEED, NHS Health Technology assessment (CRD), and Cost-Effectiveness Analysis Registry databases. Related articles were reviewed from January 2020 to the end of November 2021.ResultsOut of 1791 initial studies, 13 articles had the inclusion criteria. According to the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist, ten studies were of excellent quality, and the remaining two studies were of very good quality. Most studies were cost-effectiveness analysis studies. The entered studies had different time horizons. Diagnostic tests reviewed in the studies included real-time polymerase chain reaction (RT-PCR) test, immunoglobulin G (IgG) & Antigen, point of care tests. Although polymerase chain reaction (PCR) testing improves the quality of life and survival for patients with infected Covid-19 based on its greater effectiveness compared to standard protection protocols, due to the high cost of this intervention, it has been considered a cost-effective method in some countries.ConclusionSince most studies have been conducted in developed countries, it unquestionably does not make sense to extend these results to low-income and developing countries. Therefore further studies are required in low-income and developing countries to evaluate the cost-effectiveness of laboratory-based diagnostic methods (RT-PCR) of covid-19 in variable prevalence of infectious cases.

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Test positivity - evaluation of a new metric to assess epidemic dispersal mediated by non-symptomatic cases.

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