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Seroprevalence of and Risk Factors Associated With SARS-CoV-2 Infection in Health Care Workers During the Early COVID-19 Pandemic in Italy

Educational Objective
To identify the key insights or developments described in this article
1 Credit CME
Key Points

Question  What are the seroprevalence and the relative odds of SARS-CoV-2 infection among health care workers (HCWs) employed in different professional categories and operational units?

Findings  In this cross-sectional study of 82 961 serological tests of Italian HCWs, 12.2% of participants were positive for IgG antibodies against SARS-CoV-2. Higher odds of infection were found among nurses, health assistants, and workers enrolled in emergency departments or in treatment of patients with subacute disease.

Meaning  These findings suggest that equipment and training of personnel less accustomed to managing infectious disease but directly exposed to patients who may be infected with SARS-CoV-2 should be prioritized to decrease infection risks in health care settings.

Abstract

Importance  Identifying health care settings and professionals at increased risk of SARS-CoV-2 infection is crucial to defining appropriate strategies, resource allocation, and protocols to protect health care workers (HCWs) and patients. Moreover, such information is crucial to decrease the risk that HCWs and health care facilities become amplifiers for SARS-CoV-2 transmission in the community.

Objective  To assess the association of different health care professional categories and operational units, including in-hospital wards, outpatient facilities, and territorial care departments, with seroprevalence and odds of SARS-CoV-2 infection.

Design, Setting, and Participants  This cross-sectional study was conducted using IgG serological tests collected from April 1 through May 26, 2020, in the Lombardy region in Italy. Voluntary serological screening was offered to all clinical and nonclinical staff providing any health care services or support to health care services in the region. Data were analyzed from June 2020 through April 2021.

Exposures  Employment in the health care sector.

Main Outcomes and Measures  Seroprevalence of positive IgG antibody tests for SARS-CoV-2 was collected, and odds ratios of experiencing infection were calculated.

Results  A total of 140 782 professionals employed in the health sector were invited to participate in IgG serological screening, among whom 82 961 individuals (59.0% response rate) were tested for SARS-CoV-2 antibodies, with median (interquartile range [IQR]; range) age, 50 (40-56; 19-83) years and 59 839 (72.1%) women. Among these individuals, 10 115 HCWs (12.2%; 95% CI, 12.0%-12.4%) had positive results (median [IQR; range] age, 50 [39-55; 20-80] years; 7298 [72.2%] women). Statistically significantly higher odds of infection were found among health assistants (adjusted odds ratio [aOR], 1.48; 95% CI, 1.33-1.65) and nurses (aOR, 1.28; 95% CI, 1.17-1.41) compared with administrative staff and among workers employed in internal medicine (aOR, 2.24; 95% CI, 1.87-2.68), palliative care (aOR, 1.84; 95% CI, 1.38-2.44), rehabilitation (aOR, 1.59; 95% CI, 1.33-1.91), and emergency departments (aOR, 1.56; 95% CI, 1.29-1.89) compared with those working as telephone operators. Statistically significantly lower odds of infection were found among individuals working in forensic medicine (aOR, 0.40; 95% CI, 0.19-0.88), histology and anatomical pathology (aOR, 0.71; 95% CI, 0.52-0.97), and medical device sterilization (aOR, 0.54; 95% CI, 0.35-0.84) compared with those working as telephone operators. The odds of infection for physicians and laboratory personnel were not statistically significantly different from those found among administrative staff. The odds of infection for workers employed in intensive care units and infectious disease wards were not statistically significantly different from those of telephone operators.

Conclusions and Relevance  These findings suggest that professionals partially accustomed to managing infectious diseases had higher odds of SARS-CoV-2 infection. The findings further suggest that adequate organization of clinical wards and personnel, appropriate personal protective equipment supply, and training of all workers directly and repeatedly exposed to patients with clinical or subclinical COVID-19 should be prioritized to decrease the risk of infection in health care settings.

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Article Information

Accepted for Publication: May 3, 2021.

Published: July 6, 2021. doi:10.1001/jamanetworkopen.2021.15699

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2021 Poletti P et al. JAMA Network Open.

Corresponding Authors: Piero Poletti, Center for Health Emergencies, Bruno Kessler Foundation, via Sommarive 18, Povo, Trento 38123, Italy (poletti@fbk.eu); Marcello Tirani, Directorate General for Health, Lombardy region, via Indipendenza 3, 27100, Milan, Italy (marcello_tirani@regione.lombardia.it).

Author Contributions: Drs Poletti and Tirani had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Dr Ajelli and Mr Merler are joint senior authors.

Concept and design: Poletti, Melegaro, Ajelli, Merler.

Acquisition, analysis, or interpretation of data: Tirani, Cereda, Trentini, Guzzetta, Marziano, Toso, Piatti, Piccarreta, Melegaro, Andreassi, Gramegna, Ajelli.

Drafting of the manuscript: Poletti, Melegaro.

Critical revision of the manuscript for important intellectual content: Tirani, Cereda, Trentini, Guzzetta, Marziano, Toso, Piatti, Piccarreta, Melegaro, Andreassi, Gramegna, Ajelli, Merler.

Statistical analysis: Poletti, Trentini.

Administrative, technical, or material support: Andreassi, Gramegna.

Supervision: Poletti, Tirani, Cereda, Toso, Melegaro, Ajelli, Merler.

Conflict of Interest Disclosures: Dr Ajelli reported receiving funding for research not related to COVID-19 from Seqirus outside the submitted work. No other disclosures were reported.

Funding/Support: Drs Poletti and Guzzetta and Mr Merler acknowledge receiving funding from the European Commission H2020 project Monitoring Outbreak Events for Disease Surveillance in a Data Science Context. Drs Poletti and Guzzetta and Mr Merler acknowledge receiving funding from the Fondazione Valorizzazione Ricerca Trentina Trento project Epidemiologia e Transmissione di COVID-19 in Trentino.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

References
1.
Nguyen  LH , Drew  DA , Graham  MS ,  et al; Coronavirus Pandemic Epidemiology Consortium.  Risk of COVID-19 among front-line health-care workers and the general community: a prospective cohort study.   Lancet Public Health. 2020;5(9):e475-e483. Published online July 31, 2020. doi:10.1016/S2468-2667(20)30164-X PubMedGoogle ScholarCrossref
2.
Ranney  ML , Griffeth  V , Jha  AK .  Critical supply shortages —the need for ventilators and personal protective equipment during the COVID-19 pandemic.   N Engl J Med. 2020;382(18):e41. Published online March 25, 2020. doi:10.1056/NEJMp2006141 PubMedGoogle Scholar
3.
Leung  NHL , Chu  DKW , Shiu  EYC ,  et al.  Respiratory virus shedding in exhaled breath and efficacy of face masks.   Nat Med. 2020;26(5):676-680. doi:10.1038/s41591-020-0843-2 PubMedGoogle ScholarCrossref
4.
Hu  S , Wang  W , Wang  Y , Litvinova  M , Luo  K , Ren  L ,  et al  Infectivity, susceptibility, and risk factors associated with SARS-CoV-2 transmission under intensive contact tracing in Hunan, China.   medRxiv. Preprint posted online November 3, 2020. doi:10.1101/2020.07.23.20160317Google Scholar
5.
Szablewski  CM , Chang  KT , Brown  MM ,  et al SARS-CoV-2 transmission and infection among attendees of an overnight camp—Georgia, June 2020.  MMWR Morb Mortal Wkly Rep. 2020;69(31):362-365. doi:10.15585/mmwr.mm6931e1 Crossref
6.
Gómez-Ochoa  SA , Franco  OH , Rojas  LZ ,  et al.  COVID-19 in health-care workers: a living systematic review and meta-analysis of prevalence, risk factors, clinical characteristics, and outcomes.   Am J Epidemiol. 2021;190(1):161-175. doi:10.1093/aje/kwaa191PubMedGoogle ScholarCrossref
7.
Galanis  P , Vraka  I , Fragkou  D , Bilali  A , Kaitelidou  D .  Seroprevalence of SARS-CoV-2 antibodies and associated factors in healthcare workers: a systematic review and meta-analysis.   J Hosp Infect. 2021;108:120-134. doi:10.1016/j.jhin.2020.11.008 PubMedGoogle ScholarCrossref
8.
Iversen  K , Bundgaard  H , Hasselbalch  RB ,  et al.  Risk of COVID-19 in health-care workers in Denmark: an observational cohort study.   Lancet Infect Dis. 2020;20(12):1401-1408. doi:10.1016/S1473-3099(20)30589-2PubMedGoogle ScholarCrossref
9.
Wang  X , Ferro  EG , Zhou  G , Hashimoto  D , Bhatt  DL .  Association between universal masking in a health care system and SARS-CoV-2 positivity among health care workers.   JAMA. 2020;324(7):703-704. doi:10.1001/jama.2020.12897 PubMedGoogle ScholarCrossref
10.
Houlihan  C , Vora  N , Byrne  T , Lewer  D , Heaney  J , Moore  DA ,  et al  SARS-CoV-2 virus and antibodies in front-line health care workers in an acute hospital in London: preliminary results from a longitudinal study.   medRxiv. Preprint posted online June 9, 2020. doi:10.1101/2020.06.08.20120584Google Scholar
11.
Moscola  J , Sembajwe  G , Jarrett  M ,  et al; Northwell Health COVID-19 Research Consortium.  Prevalence of SARS-CoV-2 antibodies in health care personnel in the New York City area.   JAMA. 2020;324(9):893-895. doi:10.1001/jama.2020.14765 PubMedGoogle ScholarCrossref
12.
Jeremias  A , Nguyen  J , Levine  J ,  et al.  Prevalence of SARS-CoV-2 infection among health care workers in a tertiary community hospital.   JAMA Intern Med. 2020;180(12):1707-1709. doi:10.1001/jamainternmed.2020.4214 PubMedGoogle ScholarCrossref
13.
Calcagno  A , Ghisetti  V , Emanuele  T ,  et al.  Risk for SARS-CoV-2 infection in healthcare workers, Turin, Italy.   Emerg Infect Dis. 2021;27(1):303-305. doi:10.3201/eid2701.203027PubMedGoogle ScholarCrossref
15.
World Health Organization. Transmission of SARS-CoV-2: implications for infection prevention precautions: scientific brief. Accessed May 26, 2021. https://www.who.int/news-room/commentaries/detail/transmission-of-sars-cov-2-implications-for-infection-prevention-precautions
16.
Ferioli  M , Cisternino  C , Leo  V , Pisani  L , Palange  P , Nava  S .  Protecting healthcare workers from SARS-CoV-2 infection: practical indications.   Eur Respir Rev. 2020;29(155):200068. doi:10.1183/16000617.0068-2020PubMedGoogle Scholar
18.
Regione Lombardia. Decreto N. 3351 del 14/03/2020: disposizioni integrative in attuazione della DGR N. XI/2906 DELL’8/03/2020 per l’organizzazione della rete ospedaliera in ordine all’emergenza epidemiologica da COVID-19. Accessed May 26, 2021. https://www.osservatorionazionalescreening.it
19.
Regione Lombardia. Delibera n. 3115 del 7 maggio 2020—indirizzi per l'organizzazione delle attività sanitarie. Accessed May 26, 2021. https://www.regione.lombardia.it/wps/wcm/connect/0409d41a-e474-49cd-af65-1c2250ba07ab/DGR+n_+3115_07_05_2020.pdf?MOD=AJPERES&CACHEID=ROOTWORKSPACE-0409d41a-e474-49cd-af65-1c2250ba07ab-n8eAvAA
20.
Bonelli  F , Sarasini  A , Zierold  C ,  et al.  Clinical and analytical performance of an automated serological test that identifies S1/S2-neutralizing IgG In COVID-19 patients semiquantitatively. 2020.   J Clin Microbiol. 2020;58(9):01224-20. doi:10.1128/JCM.01224-20 PubMedGoogle ScholarCrossref
21.
GeurtsvanKessel  CH , Okba  NMA , Igloi  Z ,  et al  Towards the next phase: evaluation of serological assays for diagnostics and exposure assessment.   medRxiv. Preprint posted online May 5, 2020. doi:10.1101/2020.04.23.20077156Google Scholar
22.
Cereda  D , Tirani  M , Rovida  F ,  et al The early phase of the COVID-19 outbreak in Lombardy, Italy.  arXiv. Preprint posted March 20, 2020. Accessed May 26, 2021. https://arxiv.org/abs/2003.09320
23.
Corman  VM , Landt  O , Kaiser  M ,  et al.  Detection of 2019 novel coronavirus (2019-nCoV) by real-time RT-PCR.   Euro Surveill. 2020;25(3):2000045. doi:10.2807/1560-7917.ES.2020.25.3.2000045 PubMedGoogle Scholar
24.
Cohen  AN , Kessel  B .  False positives in reverse transcription PCR testing for SARS-CoV-2.   medRxiv. Preprint posted online May 1, 2020. Accessed May 26, 2021. https://www.medrxiv.org/content/10.1101/2020.04.26.20080911v1Google Scholar
25.
Istituto Superiore di Sanità. COVID-19 integrated surveillance: key national data. Accessed November 5, 2020. https://www.epicentro.iss.it/en/coronavirus/sars-cov-2-integrated-surveillance-data
26.
Jacob  JT , Baker  JM , Fridkin  SK ,  et al.  Risk factors associated with SARS-CoV-2 seropositivity among US health care personnel.   JAMA Netw Open. 2021;4(3):e211283. doi:10.1001/jamanetworkopen.2021.1283 PubMedGoogle Scholar
27.
Plebani  M , Padoan  A , Fedeli  U ,  et al.  SARS-CoV-2 serosurvey in health care workers of the Veneto region.   Clin Chem Lab Med. 2020;58(12):2107-2111. doi:10.1515/cclm-2020-1236 PubMedGoogle ScholarCrossref
28.
Shields  A , Faustini  SE , Perez-Toledo  M ,  et al.  SARS-CoV-2 seroprevalence and asymptomatic viral carriage in healthcare workers: a cross-sectional study.   Thorax. 2020;75(12):1089-1094. doi:10.1136/thoraxjnl-2020-215414 PubMedGoogle ScholarCrossref
29.
O’Dowd  A .  Emergency departments must not return to pre-covid days of overcrowding and lack of safety, says college.   BMJ. 2020;369:m1848. doi:10.1136/bmj.m1848 PubMedGoogle Scholar
30.
Poletti  P , Tirani  M , Cereda  D ,  et al Probability of symptoms and critical disease after SARS-CoV-2 infection.  arXiv. Preprint posted online June 15, 2020. Accessed May 26, 2021. https://arxiv.org/abs/2006.08471
31.
Stein-Zamir  C , Abramson  N , Shoob  H ,  et al.  A large COVID-19 outbreak in a high school 10 days after schools’ reopening, Israel, May 2020.   Euro Surveill. 2020;25(29):2001352. doi:10.2807/1560-7917.ES.2020.25.29.2001352 PubMedGoogle Scholar
32.
Long  QX , Tang  XJ , Shi  QL ,  et al.  Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections.   Nat Med. 2020;26(8):1200-1204. doi:10.1038/s41591-020-0965-6 PubMedGoogle ScholarCrossref
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