key: cord-0971770-od3vjuw5
authors: Pagani, G.; Conti, F.; Giacomelli, A.; Bernacchia, D.; Rondanin, R.; Prina, A.; Scolari, V.; Gandolfi, C. E.; Castaldi, S.; Marano, G.; Ottomano, C.; Boracchi, P.; Biganzoli, E. M.; Galli, M.
title: Seroprevalence of SARS-CoV-2 IgG significantly varies with age: results from a mass population screening (SARS-2-SCREEN-CdA).
date: 2020-06-24
journal: nan
DOI: 10.1101/2020.06.24.20138875
sha: 82ee99ee22f9d2f26d63e570f927056a96e00bb9
doc_id: 971770
cord_uid: od3vjuw5

Castiglione D'Adda is one of the towns earlier and more severely affected by the SARS-CoV-2 epidemic in Lombardy. In a mass screening involving 4174 out of about 4550 total inhabits, significant age-related differences in anti SARS-CoV-2 IgG seroprevalence were found, with the lowest prevalence in the youngest inhabitants.

CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted June 24, 2020. . https://doi.org/10.1101/2020.06.24.20138875 doi: medRxiv preprint

Castiglione D'Adda is one of the towns earlier and more severely affected by the SARS-CoV-2 28 epidemic in Lombardy. In a mass screening involving 4174 out of about 4550 total inhabits, 29 significant age-related differences in anti SARS-CoV-2 IgG seroprevalence were found, with the 30 lowest prevalence in the youngest inhabitants. 31 32 CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted June 24, 2020. . https://doi.org/10.1101/2020.06.24.20138875 doi: medRxiv preprint

The analysis of IgG prevalence in the different age groups was performed by logistic regression 52 models with response variable equal to 1 for positive IgG results, and 0 for negative IgG results. 53

Age and gender were included as independent variables. Results were reported in terms of 54 estimated probabilities of being positive to IgG test as a function of age, with respective 95% 55 confidence intervals. 56 57

The analysis was based on 509 subjects of the random sample with available results. The overall 59 seroprevalence found in the tested sample was 22.6% (95% confidence interval 17.2-29.1). A 60 significant effect of age was found (p<0.0001) while no significant association emerged between 61

IgG results and gender (p=0.2560). The possible existence of a non-linear effect of age was tested 62 by including spline polynomials, without significant results (p=0.9078). Furthermore, an 63 age/gender interaction effect did not result significant (p=0.5199). Estimates of probabilities of 64 being positive to IgG test, from a model including only age as independent variable, are reported in 65 susceptibility to the infection. In particular, a higher expression of ACE2 in lung tissues in 72 advanced age groups had been speculated [6, 7] . Moreover, a variable susceptibility to other 73 coronavirus such as HCoV-NL63, which also use ACE2 as cell receptor in humans, in different age 74 groups, has been also reported in different age groups [8] . 75 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted June 24, 2020. . https://doi.org/10.1101/2020.06.24.20138875 doi: medRxiv preprint common in younger subjects, could elicit a less marked, or transient, antibody response, as already 77 found in the closely related Middle East Respiratory Syndrome Coronavirus (MERS-CoV) [9] . 78 A possible confounding factor in our findings could be related to social distancing measures: 79 schools of any grade were among the first institutions to be closed in Italy, starting from the 5 th of 80

March. This could have led to a lower exposure to the infection in children in pre-scholar and 81 scholar age groups. 82

In conclusion, our findings suggest that IgG seroprevalence for SARS-CoV-2 increases with 83 increasing age and these data suggest a lower susceptibility to infection in the lower age groups. 84

These findings have important implications in epidemiology and public health, particularly in 85 designing future population screenings, and could be an important contribution in the re-opening 86 process, especially considered that more than three-fourths of the population could be still 87 susceptible to SARS-CoV-2 infection, even in an area of initially unrestricted viral circulation. We also acknowledge the non-conditioning economical support from CISOM (Corpo Italiano di 97 Soccorso dell'Ordine di Malta), Banca Mediolanum s.p.a., Fondazione Rava and FC Internazionale 98

The study was approved by University of Milan's Ethical Committee. 100 101 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted June 24, 2020. . https://doi.org/10.1101/2020.06.24.20138875 doi: medRxiv preprint

A Novel Coronavirus from Patients with Pneumonia in 129

Dynamics of the SARS-CoV-2 epidemic in the 133 earliest-affected areas in Italy: 1 Mass screening for SARS-CoV-2 serological positivity 134 (SARS-2-SCREEN)

Epidemiological and clinical characteristics of 99 cases of 136 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study

Are children less susceptible to COVID-19

Physiological and pathological regulation of ACE2

CoV-2 receptor

Angiotensin-converting enzyme-2 (ACE2)

SARS-CoV-2 and pathophysiology of coronavirus disease 2019 (COVID-19)

CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)The copyright holder for this preprint this version posted June 24, 2020. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted June 24, 2020. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)The copyright holder for this preprint this version posted June 24, 2020. . https://doi.org/10.1101/2020.06.24.20138875 doi: medRxiv preprint