Social Distancing, Mask Use, and Transmission of Severe Acute Respiratory Syndrome Coronavirus 2, Brazil, April-June 2020.

We assessed the associations of social distancing and mask use with symptomatic, laboratory-confirmed severe acute respiratory syndrome coronavirus 2 infection in Porto Alegre, Brazil. We conducted a population-based case-control study during April-June 2020. Municipal authorities furnished case-patients, and controls were taken from representative household surveys. In adjusted logistic regression analyses of 271 case-patients and 1,396 controls, those reporting moderate to greatest adherence to social distancing had 59% (odds ratio [OR] 0.41, 95% CI 0.24-0.70) to 75% (OR 0.25, 95% CI 0.15-0.42) lower odds of infection. Lesser out-of-household exposure (vs. going out every day all day) reduced odds from 52% (OR 0.48, 95% CI 0.29-0.77) to 75% (OR 0.25, 95% CI 0.18-0.36). Mask use reduced odds of infection by 87% (OR 0.13, 95% CI 0.04-0.36). In conclusion, social distancing and mask use while outside the house provided major protection against symptomatic infection.

Slow Spread of SARS-CoV-2 in Southern Brazil Over a 6-Month Period: Report on 8 Sequential Statewide Serological Surveys Including 35 611 Participants.

Objectives. To evaluate the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) over 6 months in the Brazilian State of Rio Grande do Sul (population 11.3 million), based on 8 serological surveys. Methods. In each survey, 4151 participants in round 1 and 4460 participants in round 2 were randomly sampled from all state regions. We assessed presence of antibodies against SARS-CoV-2 using a validated lateral flow point-of-care test; we adjusted figures for the time-dependent decay of antibodies. Results. The SARS-CoV-2 antibody prevalence increased from 0.03% (95% confidence interval [CI] = 0.00%, 0.34%; 1 in every 3333 individuals) in mid-April to 1.89% (95% CI = 1.36%, 2.54%; 1 in every 53 individuals) in early September. Prevalence was similar across gender and skin color categories. Older adults were less likely to be infected than younger participants. The proportion of the population who reported leaving home daily increased from 21.4% (95% CI = 20.2%, 22.7%) to 33.2% (95% CI = 31.8%, 34.5%). Conclusions. SARS-CoV-2 infection increased slowly during the first 6 months in the state, differently from what was observed in other Brazilian regions. Future survey rounds will continue to document the spread of the pandemic.

Prevalence of overweight and obesity among Brazilian adolescents over time: a systematic review and meta-analysis.

OBJECTIVE: To estimate the burden of excess weight in Brazilian adolescents. DESIGN: Systematic review with meta-analysis. SETTING: We searched the literature in four databases (MEDLINE/PubMed, EMBASE, SciELO and LILACS). Studies were included if they had cross-sectional or cohort design and enrolled Brazilian adolescents. Studies based on self-reported measures were excluded. Random effect models were used to calculate prevalence estimates and their 95 % CI. PARTICIPANTS: Brazilian adolescents (10 to 19 years old). RESULTS: One hundred and fifty-one studies were included. Trend analyses showed a significant increase in the prevalence of excess weight in the last decades: 8·2 % (95 % CI 7·7, 8·7) until year 2000, 18·9 (95 % CI 14·7, 23·2) from 2000 to 2009, and 25·1 % (95 % CI 23·4, 26·8) in 2010 and after. A similar temporal pattern was observed in the prevalence of overweight and obesity separately. In sensitivity analyses, lower prevalence of excess weight was found in older adolescents and those defined using International Obesity Task Force cut-off points. The Southeast and South regions had the highest prevalence of excess weight, overweight and obesity. No significant difference in prevalence by sex was found, except for studies before the year 2000. CONCLUSIONS: The prevalence of overweight and obesity in Brazilian adolescents is high and continues to rise. Public policies on an individual level and targeting modifications in the obesogenic environment are necessary.

Prevalence of breastfeeding and its obstacles in patients with CHD in southern Brazil.

INTRODUCTION: Breast milk is nutritionally adequate and is related to the reduction of various health problems in childhood. Its offer is widely recommended in health guidelines. OBJECTIVE: To estimate the prevalence and obstacles to breastfeeding in patients with CHD in southern Brazil. METHODS: Cross-sectional study of patients with CHD between 2 and 18 years of age. Patients with genetic syndromes and patients whose mothers had died were excluded from the analysis. The variables on breastfeeding in the first 2 years of life were collected through a phone call to the mothers, which was conducted by trained evaluators. Prevalence was described in proportions and the continuous variables as means and standard deviation. Bivariate analyses were evaluated using a chi-square test to measure the association between the variables and the outcome. RESULTS: A total of 351 patients with CHD were analysed. There was a predominance of males (53%) and a mean age of 9.54 ± 4.52 years. Breastfeeding up to the sixth month was present in 40% of the cases. CONCLUSION: The mothers of babies with CHD face great challenges to maintain the supply of breast milk, whether inherent to the practice of breastfeeding or related to CHD.

Effect of yerba mate and green tea on paraoxonase and leptin levels in patients affected by overweight or obesity and dyslipidemia: a randomized clinical trial.

BACKGROUND: This study aimed to evaluate the effect of the intake of yerba mate (YM) and green tea (GT) on serum levels of leptin and paraoxonase-1 (PON-1), compared to control. METHODS: Controlled, randomized clinical trial (RCT) that evaluated 142 men and women affected by overweight or obesity aged 35-60 years, untreated dyslipidemia and no history of coronary artery disease. Participants were randomized to ingest 1000 mL GT, YM or apple tea (AT, control group) daily, during eight weeks. Serum PON-1 and leptin levels were analyzed by ELISA immunoassay at the beginning (baseline) and after eight weeks of intervention. RESULTS: The intake of 1 l of YM/day resulted in significant increase in serum levels of PON-1 (9.7%; p = 0.005). The consumption of GT induced no significant difference in the levels of PON-1 (p = 0.154) and leptin (p = 0.783). Intergroup analysis showed a significant difference (p = 0.036) in the variation of PON-1 levels in the YM group when compared to GT and AT groups. In addition, the increase in PON-1 levels in the YM group was significantly associated with increased HDL-c (p = 0.004). CONCLUSIONS: The intake of yerba mate increased the antioxidant capacity by increasing serum levels of PON-1 and was positively associated with increased HDL-c, stressing the protective role of this beverage against atherosclerotic diseases. GT intake had no significant effect on serum levels of PON-1 and leptin. TRIAL REGISTRATION: This study is registered with ClinicalTrials.gov under protocol number NCT00933647.

Trends and determinants of change in compliance to dietary guidelines in a Swiss community-dwelling sample.

Adherence to dietary guidelines is associated with significantly better health outcomes. Studies across the world shows that compliance with the guidelines was low, but data in Switzerland are lacking. Hence, we aimed to assess the 5-year trends in dietary compliance regarding food guidelines in Switzerland in a prospective, population-based observational study. Data from 2882 participants (1591 women, 35-75 years), from the first (2009-2012) and second (2014-2017) follow-up. Dietary intake was assessed using a validated food frequency questionnaire. Compliance with the guidelines of the Swiss society of nutrition was assessed at baseline and 5.5 years afterwards. Prevalence rates for compliance were calculated using the exact Poisson method. Factors associated with changes in compliance (never, shifter or maintainer) were assessed by multinomial logistic regression using "Never compliers" as reference. Overall, improvements in compliance to fruits (42.4% to 45.1%) vegetables (6.9% to 8.6%) and fish (66.6% to 60.5%) were found, while compliance to meat decreased (61.1% to 58.5%). The prevalence of participants complying with at least three dietary recommendations did not change (24.1% to 25.2%). During follow-up, only 11.6% of participants maintained compliance to at least three dietary recommendations, and 62.4% never managed to comply. Female gender and older age were associated with maintaining compliance during the two study periods. In conclusion, compliance with dietary guidelines is a dynamic status, and only a small fraction of the population achieves sustained compliance with at least three guidelines. Almost two thirds of the population never achieve compliance with three guidelines.

Serum C-reactive protein levels and body mass index in children and adolescents with CHD.

BACKGROUND: The prevalence of overweight in children with CHD is about 26.9%. Increase in adipose tissue is related to the secretion of proinflammatory markers such as C-reactive protein. Assuming that children with CHD are exposed to other inherent risk factors for heart disease, our objective was to evaluate the correlation between levels of C-reactive protein and body mass index in children and adolescents with CHD. METHODS: A cross-sectional study with 377 children and adolescents with CHD in a clinical setting of a reference hospital was carried out. C-reactive protein data were collected after 12 hours of fasting. Nutritional status was classified according to body mass index. The patients were divided into three groups: cyanotic, acyanotic, and minimal heart defects (controls). RESULTS: The mean age was 9.9±4.2 years, and 53.6% of the sample included males. The cyanotic group represented 22.3%, acyanotic 42.2%, and minimal defects 35.5% of the sample. The average body mass index percentile was 57.23±32.06. The median values of C-reactive protein were as follows: cyanotic 0.340, acyanotic with clinical repercussion 0.203, and minimal defects 0.128. There was a significant difference between the minimal defects and the cyanotic groups (p=0.023). There was a significant correlation between C-reactive protein and body mass index percentile (r=0.293, p<0.01). C-reactive protein levels were higher in girls (p=0.034). There were no significant correlations between C-reactive protein and age or birth weight. CONCLUSION: The correlation between body mass index percentile and C-reactive protein was confirmed in this population. The prevention of overweight is paramount to avoid overlapping modifiable risk factors to those already inherent to the CHD.

Prevalence of ophthalmological abnormalities in children and adolescents with CHD: systematic review and meta-analysis of observational studies.

BACKGROUND: CHDs form a complex and heterogeneous group of clinical entities, with high morbidity and mortality. With the advancement of surgical and invasive techniques and clinical treatment, the survival of these patients has increased significantly, and there are reports of a high prevalence of ocular abnormalities in this group. The objective of this study was to estimate the prevalence of ocular findings in children and adolescents diagnosed with CHD. METHODS: A systematic search was conducted in the following databases: MEDLINE (via PubMed), EMBASE, and Cochrane CENTRAL, in addition to a manual search on studies published on the patient, from inception until August, 2014. Observational studies assessing the prevalence of ocular abnormalities in children and adolescents with CHDs were included. RESULTS: Of the 2413 articles identified, eight were included, comprising a total of 1061 patients. Among them, the lowest and highest prevalences observed were 6.3 and 65%, respectively. The weighted average prevalence of ocular abnormalities was 32.5% (CI95% 19.3-49.3). Strabismus, cataracts, and retinopathy were the most frequently observed alterations. CONCLUSION: The prevalence of ocular abnormalities in children and adolescents with CHDs was 32.5%, demonstrating that ocular consequences are not uncommon in this population and may have relevant clinical impact. These results reinforce the need for ophthalmological evaluation of patients with CHDs.

The "Happy Heart" educational program for changes in health habits in children and their families: protocol for a randomized clinical trial.

BACKGROUND: The prevalence of childhood obesity increased worldwide in recent decades and is associated with risk factors for the development of chronic diseases in adulthood. Strategies for health promotion directed at an early age, with recommendation for healthy habits, can achieve good results. The objective of this study is to evaluate the effectiveness of an innovative, simple and cost effective educational program to improve eating habits, physical activity and the knowledge about healthy habits in children, as well as in their families, as compared to routine outpatient care. METHODS/DESIGN: The study is designed as a randomized clinical trial. Sample size is estimated to include 37 children, aged between 7 and 11 years, and their guardians, randomized for an intervention or a control group. The intervention will consist of 11-weekly group meetings of nutritional education and distribution of explanatory material, with orientation about healthy food and family habits and physical activity. Recreational, simple and low cost resources, carefully designed for the presentation of contents to the children and parents, will be used in all meetings. The control group will receive standard outpatient care based in individual clinical practice guidelines. The primary outcomes will be changes in dietary habits, knowledge and physical activity of children and adults. The secondary outcomes will be changes of body mass index, waist circumference, systolic and diastolic blood pressure and laboratory tests, in children and adults. DISCUSSION: The Happy Heart Study offers a playful and low-cost approach for the prevention and control of obesity and cardiovascular disease in children. Although this program is being planned for implementation in Brazil, the method can be adapted to many other countries. REGISTRY OF PROTOCOL: Protocol registered on the site ensaiosclinicos.gov.br: RBR-8ttw64.

Exercise capacity in children and adolescents with corrected congenital heart disease.

Congenital heart disease promotes hemodynamic changes that can contribute to reduce exercise capacity. The aim of the study was to evaluate the exercise capacity of children and adolescents with cyanotic congenital heart disease and to assess respiratory muscle strength, plasma levels of B-type natriuretic peptide and ventricular ejection fraction, as well the associations between these variables. Cross-sectional study that evaluated 48 patients between 6 and 18 years-old that underwent a six-minute walk test (6MWT), respiratory muscle strength, dosage of B-type natriuretic peptide and echocardiography. The mean age was 13.3 ± 4.1 years, and the most prevalent heart disease was tetralogy of Fallot (54.2 %). The average distance walked was 452.7 ± 73.2 m, significantly below the predicted (69 %) (p < 0.001). The maximum inspiratory pressure was above the predicted result (111.4 %), average 58.2 ± 22.3 (p = 0.56), and the maximum expiratory pressure was 63.2 ± 23.3 cm H2O, significantly below the predicted (63 %) (p < 0.001). The level of B-type natriuretic peptide was elevated in all patients, with a median of 2087.17 (502.54-4,768.05). The ventricular ejection fraction showed a median of 65.9 (41-100). There was no correlation between the 6MWT, ventricular ejection fraction (r = -0.05; p = 0.72), inspiratory muscle strength (r = 0.03; p = 0.81), expiratory muscle strength (r = 0.09; p = 0.05) and B-type natriuretic peptide (r = -0.04; p = 0.77). Children and adolescents with cyanotic congenital heart disease present a lower exercise capacity and expiratory muscle strength. No associations were found between exercise capacity, respiratory muscle strength, B-type natriuretic peptide and left ventricular ejection fraction.

Health-related quality of life in adolescents with congenital heart disease.

PURPOSE: This study aims to evaluate the health-related quality of life of adolescents with congenital heart disease, describing health-related quality of life according to the diagnosis and severity of congenital heart disease, identified by variables such as the presence of symptoms, surgical interventions, use of medication, and residual lesion. METHODS: A cross-sectional study was conducted on 203 adolescents with congenital heart disease attended at the Pediatric Cardiology ambulatory of a reference hospital in Brazil. The Brazilian version of the questionnaire KIDSCREEN-27 was used for the assessment of health-related quality of life. Information related to the congenital heart disease diagnosis and clinical variables were collected from the medical records of the patients. RESULTS: There was no statistically significant difference between acyanotic and cyanotic groups, as well as for the different diagnosis of congenital heart disease. A trend for better health-related quality of life in the dimension of Psychological Well-Being (p=0.054) was found in the groups with surgical intervention and use of medication. Adolescents that referred a good general health presented significantly better results in all dimensions of health-related quality of life, except for Autonomy and Parent Relation, than those who presented clinical symptoms (p<0.05). CONCLUSIONS: Type of congenital heart disease and initial diagnosis did not seem to affect the perception of health-related quality of life, corroborating findings of several studies. Surgical interventions and the use of medication can improve previous clinical status, and therefore it seems to be beneficial in terms of Psychological Well-Being. The presence of clinical symptoms was the variable that caused the largest impact on the perception of health-related quality of life, possibly because of the impairment they bring to the daily lives of these patients.

Physical activity and cardiovascular risk factors in children: meta-analysis of randomized clinical trials.

OBJECTIVE: To assess the effects of physical activity interventions in preventing cardiovascular risk factors in childhood through a systematic review and meta-analysis of randomized clinical trials (RCTs). METHODS: A search of online databases (PubMed, EMBASE and Cochrane CENTRAL) was conducted from inception until June 2013. RCTs enrolling children 6-12years old conducted physical activity interventions longer than 6months, assessing their effect on body mass index (BMI), systolic (SBP) and diastolic blood pressure (DBP), total cholesterol (TC) and triglycerides (TG) were included. Data analysis was performed using a random-effects model. RESULTS: Of 23.091 articles retrieved, 11 RCTs (10.748 subjects) were included. Physical activity interventions were not associated with reductions of BMI [-0.03kg/m(2) (95%CI -0.16, 0.13) I(2) 0%]. However, there was an association between the interventions and reduction of SBP [-1.25mmHg (95%CI -2.47, -0.02) I(2) 0%], DBP [-1.34mmHg (95%CI -2.57, -0.11) I(2) 43%] and TG [-0.09mmol/L (95%CI -0.14, -0.04) I(2) 0%], and increase of TC [0.14mmol/L (95%CI 0.01, 0.27) I(2) 0%]. CONCLUSION: As physical activity intervention programs lasting longer than 6months are associated with reductions in blood pressure levels and triglycerides, they should be considered to be included in prevention programs for cardiovascular diseases in schoolchildren.

Overweight and obesity in children with congenital heart disease: combination of risks for the future?

BACKGROUND: Children who have unhealthy lifestyles are predisposed to develop hypertension, dyslipidemia and other complications. The epidemic of obesity is also affecting children with congenital heart disease. The aim of this study is to estimate the prevalence of obesity and describe associated risk factors, including family history in children with congenital heart disease. METHODS: A cross-sectional study with 316 children and adolescents with congenital heart disease seen in an outpatient clinic of a reference hospital. Collected sociodemographic data included family history of chronic disease, dietary habits, laboratory tests (total cholesterol, HDL and LDL/cholesterol, triglycerides, fasting glucose, CRP, hematocrit and hemoglobin), and anthropometric assessment. Anthropometric data of the caregivers was self-reported. RESULTS: The prevalence of excess weight was 26.9%. Altered levels of total cholesterol were observed in 46.9%, of HDL in 32.7%, LDL in 23.6% and of triglycerides levels in 20.0%. A higher frequency of family history of obesity (42.6%; p = 0.001), dyslipidemia (48.1%; p = <0.001), diabetes (47.4%; p = 0.002), hypertension (39.2%; p = 0.006) and ischemic disease (43.7%; p = 0.023), as well as significantly higher values of triglycerides (p = 0.017), glycemia (p = 0.004) and C-reactive protein (p = 0.002) were observed among patients with excess weight. CONCLUSION: The presence of modifiable risk factors and the variables associated to excess weight in this population was similar to that described in the literature for children without congenital disease. As these children already present the risks associated to heart disease, it is particularly important to promote a healthy lifestyle in this group.

Molecular screening for 22Q11.2 deletion syndrome in patients with congenital heart disease.

Few studies have investigated the prevalence of 22q11.2 deletion syndrome (22q11.2DS) among patients with isolated heart defects or nonconotruncal heart defects. Polymerase chain reaction (PCR) followed by length polymorphism restriction fragment analysis (RFLP) is useful for low-cost molecular diagnosis and screening. This cross-sectional study included 392 patients with congenital heart disease, described clinical features, and performed PCR-RFLP for analysis of polymorphism in three loci with a high heterozygosity rate located in the typically deleted region of 1.5 megabases. Heterozygosity excluded 22q11.2DS. Patients with homozygosity for the three markers underwent multiplex ligation-dependent probe amplification (MLPA) and fluorescence in situ hybridization (FISH) for the final diagnosis, estimating the prevalence of 22q11.2DS. The use of PCR-RFLP excluded 22q11.2DS in 81.6 % (n = 320) of 392 patients. Of the remaining 72 patients, 65 underwent MLPA, showing 22q11.2DS in five cases (prevalence, 1.27 %). Four of these five patients underwent FISH, confirming the MLPA results. All five patients with the deletion had heart diseases commonly found with 22q11.2DS (interrupted aortic arch, persistent truncus arteriosus, tetralogy of Fallot, and ventricular septal defect plus atrial septal defect). Two patients had congenital extracardiac anomaly (one with arched palate and micrognathia and one with hypertelorism). Three patients reported recurrent respiratory infections, and one patient reported hypocalcemia. All were underweight or short in stature for their age. This study contributed to showing the prevalence of 22q11.2DS in patients with any congenital heart disease, with or without other features of the syndrome. Patients with 22q11.2DS may not have all the major features of the syndrome, and those that are found may be due to the heart defect.

Educational interventions in childhood obesity: a systematic review with meta-analysis of randomized clinical trials.

OBJECTIVE: To assess the effectiveness of educational interventions including behavioral modification, nutrition and physical activity to prevent or treat childhood obesity through a systematic review and meta-analysis of randomized trials. METHOD: A search of databases (PubMed, EMBASE and Cochrane CENTRAL) and references of published studies (from inception until May 2012) was conducted. Eligible studies were randomized trials enrolling children 6 to 12 years old and assessing the impact of educational interventions during 6 months or longer on waist circumference, body mass index (BMI), blood pressure and lipid profile to prevent or treat childhood obesity. Calculations were performed using a random effects method and pooled-effect estimates were obtained using the final values. RESULTS: Of 22.852 articles retrieved, 26 trials (23.617 participants) were included. There were no differences in outcomes assessed in prevention studies. However, in treatment studies, educational interventions were associated with a significant reduction in waist circumference [-3.21 cm (95%CI -6.34, -0.07)], BMI [-0.86 kg/m(2) (95%CI -1.59, -0.14)] and diastolic blood pressure [-3.68 mmHg (95%CI -5.48, -1.88)]. CONCLUSIONS: Educational interventions are effective in treatment, but not prevention, of childhood obesity and its consequences.

Knowledge and food practices questionnaire: construction and validation.

OBJECTIVES: To develop and validate an instrument about nutritional knowledge and feeding practices to be used in children aged 7-11 years, based on the latest Brazilian Food Guide. METHODS: Review on the subject; instrument creation; content validity with two groups of judges: first, nutritionists and, after adjustments, a multidisciplinary group (content validity index [CVI]); FACE validity; reproducibility analysis (intraclass correlation coefficient [ICC], level of agreement, and kappa [k]); internal consistency analysis (Cronbach's alpha[α]) and construct validity (Kaiser-Meyer-Olkin and exploratory factorial analysis). The sample was calculated, considering at least ten subjects for each question of the questionnaire. RESULTS: There was a final sample of 453 children (53.6% girls), with a mean age of 9.45 years (SD = 1.44). The content validity showed a CVI ≥ 0.80 for relevance in 62.3% of the items for nutritionists' group and 100% of the items for the multidisciplinary group, clarity (49.4%, 91.8%), and pertinence (58.8%, 98.4%), respectively. The test-retest showed a level of agreement of 84.3% and k = 0.740 for the Knowledge dimension and ICC = 0.754 for the Food Practices dimension. The internal consistency showed α = 0.589 for the Knowledge dimension and α = 0.618 for the Food Practices dimension. For the construct validity, Kaiser-Meyer-Olkin was 0.724 and exploratory factorial analysis showed a variance of 47.01 with varimax rotation and defined five factors for the Practices Dimension. CONCLUSION: The Food Knowledge and Practices Questionnaire (Questionário de Conhecimento e Práticas Alimentares [QCPA]) instrument showed validity and reliability to assess nutritional knowledge and food practices in children aged 7-11 years.

Translation, cross-cultural adaptation, and validation of the Leuven Knowledge Questionnaire for congenital heart disease instrument into Brazilian Portuguese.

OBJECTIVE: To translate the Leuven Knowledge Questionnaire for Congenital Heart Disease into Brazilian Portuguese and to validate its psychometric properties with parents and family caregivers of children with congenital heart disease. METHOD: This was a six-step methodological study, including the translation, synthesis, back-translation, evaluation of the version translated by the committee of experts, pre-testing, and validation, for which two pilot tests were used including the think-aloud protocol. The content validity index and the frequency of socioeconomic data were calculated in a statistical programming environment. RESULTS: In content validation, the instrument showed good applicability among experts, with average content validity index of 0.8-1, while kappa agreement analysis was between 0.76 to 1; both results were considered adequate for validation. CONCLUSIONS: The results suggest reliability among the evaluators, indicating the instrument's accuracy and the possibility of using it to assess the knowledge of parents and family caregivers about congenital heart disease.

Diagnostic Properties of Three SARS-CoV-2 Antibody Tests.

Serological assays emerged as complementary tools to RT-PCR in the diagnosis of SARS-CoV-2 as well as being needed for epidemiological studies. This study aimed to assess the performance of a rapid test (RT) compared to that of serological tests using finger prick blood samples. A total of 183 samples were evaluated, 88 of which were collected from individuals with negative RT-PCR and 95 from positive RT-PCR individuals. The diagnostic performance of RT (WONDFO®) and LUMIT (PROMEGA®) were compared to that of ELISA (EUROIMMUN®) for detecting antibodies against SARS-CoV-2 according to time from symptoms onset. The IgG antibody tests were detected in 77.4% (LUMIT), 77.9% (RT), and 80.0% (ELISA) of individuals. The detection of antibodies against SARS-CoV-2 increases in accordance with increasing time from symptoms onset. Considering only time from symptoms onset >21 days, the positivity rate ranged from 81.8 to 97.0% between the three tests. The RT and LUMIT showed high agreement with ELISA (agreement = 91.5%, k = 0.83, and agreement = 96.3%, k = 0.9, respectively) in individuals who had symptoms 15 to 21 days before sample collection. Compared to that of the ELISA assay, our results show sensitivity ranged from 95% to 100% for IgG antibody detection in individuals with symptoms onset between 15 and 21 days before sample collection. The specificity was 100% in individuals with symptoms onset >15 days before serological tests. This study shows good performance and high level of agreement of three immunoassays for the detection of SARS-CoV-2 antibodies.

High prevalence of symptoms among Brazilian subjects with antibodies against SARS-CoV-2.

Since the beginning of the pandemic of COVID-19, there has been a widespread assumption that most infected persons are asymptomatic. Using data from the recent wave of the EPICOVID19 study, a nationwide household-based survey including 133 cities from all states of Brazil, we estimated the proportion of people with and without antibodies for SARS-CoV-2 who were asymptomatic, which symptoms were most frequently reported, number of symptoms and the association with socio-demographic characteristics. We tested 33,205 subjects using a rapid antibody test previously validated. Information was collected before participants received the test result. Out of 849 (2.7%) participants positive for SARS-CoV-2 antibodies, only 12.1% (95% CI 10.1-14.5) reported no symptoms, compared to 42.2% (95% CI 41.7-42.8) among those negative. The largest difference between the two groups was observed for changes in smell/taste (56.5% versus 9.1%, a 6.2-fold difference). Changes in smell/taste, fever and body aches were most likely to predict positive tests as suggested by recursive partitioning tree analysis. Among individuals without any of these three symptoms, only 0.8% tested positive, compared to 18.3% of those with both fever and changes in smell or taste. Most subjects with antibodies against SARS-CoV-2 are symptomatic, even though most present only mild symptoms.

Prevalence of symptoms of COVID-19 in the state of Rio Grande do Sul: results of a population-based study with 18,000 participants.

OBJECTIVE: To evaluate the prevalence of reports of symptoms of COVID-19 among individuals with and without antibodies and identify those with greater capability to predict the presence of antibodies against SARS-CoV-2. METHODS: The study uses data collected in phases 5 to 8 of Epicovid-19-RS. The presence of antibodies against SARS-CoV-2 was evaluated by a rapid test. The occurrence of cough, fever, palpitations, sore throat, difficulty breathing, changes in taste and smell, vomiting, diarrhea, body pain, shaking, and headache since March 2020 was also evaluated. Then, the capability to predict the evaluated symptoms concerning the presence of antibodies was calculated. RESULTS: A total of 18,000 individuals were interviewed and 181 had antibodies against COVID-19 in phases 5 to 8. The proportion of asymptomatic individuals was 19.9% among participants with antibodies and 49.7% among those without antibodies. All symptoms were reported more frequently by individuals with antibodies. The division of the prevalence of symptoms among individuals with antibodies by the prevalence among individuals without antibodies showed the following prevalence ratios: for changes in smell or taste (9.1), fever (4.2), tremors (3.9), breathing difficulty (3.2) and cough (2.8 times). Anosmia and fever were the symptoms with a greater capability to predict the presence of antibodies. CONCLUSION: The prevalence of symptoms was higher among individuals with antibodies against SARS-CoV-2. The proportion of asymptomatic individuals was low. Altered smell or taste and fever were the symptoms that most predict the presence of antibodies. These results can help to identify probable cases, contributing to the clinical diagnosis and screening of patients for testing and isolation guidance in positive cases, especially in scenarios of the scarcity of diagnostic COVID-19 tests.