These findings have important implications in epidemiology and public health, particularly in designing future population screenings, and could be an important contribution in the re-opening process, especially considered that more than three-fourths of the population could be still susceptible to SARS-CoV-2 infection, even in an area of initially unrestricted viral circulation

These findings have important implications in epidemiology and public health, particularly in designing future population screenings, and could be an important contribution in the re-opening process, especially considered that more than three-fourths of the population could be still susceptible to SARS-CoV-2 infection, even in an area of initially unrestricted viral circulation. Declaration of Competing Interests The authors declare no conflicts of interest. 4% of the total population. At the same time, 47 deaths were officially attributed to COVID-19. In this study, the entire population of Castiglione D’Adda was invited to perform a lateral-flow immunocromatographic assessments on capillary blood (Prima Lab, Switzerland) from the 18th of May to the 7th of June. News about the mass screening was disseminated by the town municipality. A random sample of 562 subjects (stratified per sex and age) was invited to undergo confirmatory tests by chemiluminescent method?on venipuncture drawn blood (CLIA, IgG anti-SARS-CoV-2, Abbott, USA) and SARS-CoV-2 PCR on NPS, regardless of RICT results. More detailed information about the randomization procedure and the study design are available on the complete protocol, published on medrXiv pre-print server3. The analysis of IgG prevalence in the different age groups was performed by logistic regression models with response variable equal to 1 for positive IgG results, and 0 for unfavorable IgG results. Age and gender were included as impartial variables. Results were reported in terms of estimated probabilities of being positive to IgG test as a function of age, with respective 95% confidence intervals. Results presented in this paper are based on 509 people selected in the random sample who agreed to undergo venipuncture to perform CLIA serologies. Characteristics of the selected population are reported in Table?1 . Table 1 Characteristics of 509 subjects in the random sample. thead th valign=”top” rowspan=”1″ colspan=”1″ /th th valign=”top” rowspan=”1″ colspan=”1″ IgG unfavorable ( em n /em ?=?394) /th th valign=”top” rowspan=”1″ colspan=”1″ IgG positive ( em n /em ?=?115) /th /thead Gender (Female)200 (50?8%)49 (42?6%)Age (years; median, SD)46?0, 20?655?4, 19?5Age groups:?0C1956 (91?8%)5 (8?2%)?20C3992 (82?9%)19 (17?1%)?40C59142 (78?0%)40 (22?0%)? 60104 (67?1%)51 (32?9%)Contact with verified case93 (23?6%)61 (53?0%)Smoker92 (23?4%)10 (8?7%)Cardiovascular diseases?CAD/MI10 (2?5%)3 (4?3%)?Arrhythmias14 (3?6%)5 (4?3%)?Hypertension68 (17?3%)32 (27?8%)?Other14 (3?6%)14 (12?2%)At least one of the above:84 (21?3%)47 (40?9%)Rheumatic diseases19 (4?8%)11 (9?6%)Diabetes mellitus12 (3?0%)6 (6?2%)Chronic Lung diseases?Asthma20 (5?1%)2 (1?7%)?COPD1 (0?3%)1 (0?9%)?Other9 (2?3%)4 (3?5%)At least one of the above:29 (7?4%)7 (6?1%)Oncological pathologiesSolid Tumors20 (5?1%)6 (5?2%)Oncochematological2 (0?5%)2 (1?7%)At least one of the above:22 (5?6%)8 (7?0%)Symptomatic?Fever65 (16?5%)66 (57?4%)?Cough57 (14?5%)31 (27?0%)?Anosmia23 (5?8%)37 (32?2%)?Dysgeusia27 (6?9%)46 (40?0%)?Dispnea23 (5?8%)13 (11?3%)?Rush:11 (2?8%)4 (3?5%)?Arthromyalgia34 (8?6%)36 (31?3%)At least one of the above:124 Rabbit polyclonal to GHSR (31?5%)89 (77?4%)Other symptoms54 (13?7%)23 (20?0%) Open in a separate window Numerical variables are presented as means. CAD: Coronary Artery Disease; MI: Miocardial Infarction; COPD: Chronic Obstructive Pulmonary Disease. The overall seroprevalence found in the tested sample was 22.6% (95% confidence interval 17.2%- 29.1%). Interestingly, seroprevalence increases with increasing age (as shown in Table?1). In multivariate analyses, a significant effect of age was found ( em p /em 0.0001) while no significant association between IgG positivity and gender emerged ( em p /em ?=?0.2560). The possible AG 957 existence of a nonlinear effect of age was tested by including spline polynomials, without significant results ( em p /em ?=?0.9078). Furthermore, an age/gender interaction effect did not result significant ( em p /em ?=?0.5199). Estimates of probabilities of being positive to IgG test, from a model including only age as independent variable, are reported in Fig.?1 . Open in a separate window Fig. 1 Estimated probability of IgG positivity as a function of age Solid line: estimates, dashed lines: 95% confidence intervals. Since the early phases of the pandemic, advanced age was identified as an independent predictor for severe disease and worse outcomes4. Beside this, it remains unclear if the limited number of cases reported in children5 is due to a milder course of disease, with a larger percentage of asymptomatic cases, or to a lower susceptibility to contamination, as our results seem to suggest. Different ACE2 expression according to age have been postulated to explain clinical expression and susceptibility to the contamination. In particular, a higher expression of ACE2 in lung tissues in advanced age groups had been speculated6 , AG 957 7. Moreover, a variable susceptibility to other coronavirus such as HCoV-NL63, which also use ACE2 as cell receptor in humans, in different age groups, has been also reported in different age groups8. Another possible explanation may be that an asymptomatic/pauci-symptomatic contamination, more common in younger subjects, could elicit a less marked, or transient, antibody response, as already found in the closely related Middle East Respiratory Syndrome Coronavirus (MERS-CoV)9. AG 957 A possible confounding factor in our findings could be related to social distancing measures: schools of any grade were among the first institutions to be closed in Italy, starting.