A population-based study of the prevalence of COVID-19 infection in Espírito Santo, Brazil: methodology and results of the first stage

Abstract

BACKGROUND: COVID-19 is affecting almost the entire world, causing more than four hundred thousand deaths and undermining the health care systems, as much as the economy, of the afflicted countries. The strategies for prevention depend on largely lacking information, as infection prevalence and virus pathogenicity. This study aimed to determine the prevalence, the pathogenicity, and the speed of infection spreading in a large population in Brazil. MATERIALS AND METHODS: This is a serial cross-sectional study designed on a population basis and structured over houses as the sampling units. The sampling consisted of four visits at 15 days intervals in randomly selected census-designated sectors of the State major municipalities (reference municipalities) and two visits at 30 days intervals in smaller municipalities of the same regions of those of reference. At each visit, the investigators sampled houses and sampled one individual in each house for data collection. After the informed consent, the investigators performed a rapid antibody detection test (Celer Technology, Inc) and applied a questionnaire containing clinical and demographic questions. RESULTS: From May 13th to 15th, the investigators performed 6,393 rapid tests in 4,612 individuals of the reference municipalities, 1,163 individuals of the smaller municipalities, and 166 contacts of the positive individuals. Ninety-seven dwellers were positive in the reference municipalities, giving a prevalence of 2.1% (CI 95%: 1.67-2.52%). In the smaller municipalities, the figure was 0.26% (CI 95%: 0.05%-0.75%) (three positives). There was an association of the positive result with female sex (p = 0.013) and houses with five dwellers or more (p = 0.003). Seventy-eight positive individuals reported symptoms in the previous 15 days (80.4%), being anosmia (45.4%), cough (40.2%), and myalgia (38.1%) the more frequent. About one-third of them reported fever (28.9%). CONCLUSIONS: The results reveal a still small prevalence of infection in the study area, despite the significant number of sick people overloading the health system. The figures indicate an important underreporting in the area and a frequency that still can grow, making necessary public health actions for the containment of the transmission.

Population-based prevalence surveys during the COVID-19 pandemic: a systematic review

“…The same proportion of studies validated their methods internally to report accuracy (16,21,23,24,30,32,(34)(35)(36)(37)(38)(39)45,50,52) or used sensitivity and specificity given by manufacturers or other external studies (18)(19)(20)22,36,(40)(41)(42)(44)(45)(46)(47)(48)(49)(50)(51). We also noticed that it is quite unclear if the field teams followed standardized protocols for the data collection and testing.…”

“…A strong trend was observed in relation to the sampling procedures used in Brazil. All studies used a standardized household sampling method based on census tracts (46)(47)(48)(50)(51)(52) or healthcare units (49). is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint…”

“…Middle East Respiratory Syndrome (MERS) (59) coronaviruses epidemics, which was reported to lay between 0% and 7.5%. However, in the case of COVID-19, these rates were widely variable among PCR-positive and/or seropositive, ranging from 19.6% (47) to 69% (23). Older age groups were correlated with SARS-CoV-2 infection among symptomatic participants (28,29), and there was no statistical difference in the viral load of symptomatic versus asymptomatic (29).…”

SARS-CoV-2 antibody prevalence in Brazil: results from two successive nationwide serological household surveys

“…9 Three population-based antibody surveys done in the south and southeast regions of Brazil showed prevalence ranging from 0·05% to 2·1%. 10 , 11 , 12 …”

Vigilância em saúde da COVID-19 no Brasil: investigação de contatos pela atenção primária em saúde como estratégia de proteção comunitária

“…Another concern is the spread of the disease to the interior regions of the country, these being places where hospital bed infrastructure is sparse, as the majority are concentrated in large urban conurbations. 6 This context makes it fundamental to rationalize resources and structure care flows which provide for case follow-up within the territories responsible for them and prioritize care and continuous follow-up. As such, this article proposes a flowchart to strategically assist the organization of the territory-based primary health care (PHC) service network, scaling up interventions by making the population's everyday life the central point of care in relation to COVID-19.…”