COVID-19 in Workplaces: Secondary Transmission

Abstract

Objectives Coronavirus disease (COVID-19) contagion at work is well studied for healthcare workers, however it is not enough assessed in other working settings. Very little is known, indeed, about the risk of COVID-19 transmission through occupational exposure in non-health working places. This study aims to describe a COVID-19 cluster among workers in an office in Italy. Methods This was a retrospective observational study on a cluster of COVID-19 that occurred from 20 November through 3 December 2020 in a group of six colleagues (A–F) working in the same office full time 5 days a week, 8 h a day. The workers used the following prevention measures: social distancing (desks were >1 m, 1.76–5.01 m range), plexiglas panels, hands disinfection, and use of face mask. However, they did not wear face mask when in static position sitting at their desk and they did not aerate the place frequently. Results The disease spread from one worker (subject A) to four (80%) of the five colleagues (subjects B–F). Only subject D was negative to COVID-19 on 14 days after last contact with subject A (20 November 2020) as confirmed by nasopharyngeal swab testing. Subject D, in particular, did not contact subject A in the 48 h before symptoms onset. COVID-19 positivity of subject A was promptly communicated to the colleagues, who started self-isolation from their relatives and none of their households were infected. COVID-19 transmission was observed only in households of subject A. Conclusions The rapid communication of COVID-19 positivity to the colleagues and the prompt isolation of index case’s close contacts allowed to eliminate the secondary transmission to their households. The contagion of index case’s colleagues occurred from second day before symptoms onset. Distancing of >1 m, use of plexiglass panels, sanitizing hand gel, and inconstant use of face mask may not be enough for infection prevention in closed places with poor ventilation and high occupancy.

Long distance airborne transmission of SARS-CoV-2: rapid systematic review

“…Fifty six additional reports identified from the Comber et al rapid review 21 and by citation analysis were also assessed. From these 146 reports, 124 were excluded (see supplementary material 1 (section 3) for list of reasons for exclusion), and 22 reports 1 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 relating to 18 studies were included. When two or more reports related to the same study, we considered the most comprehensive report as the main publication.…”

“… 36 Eight studies were conducted in Asia, 34 35 36 37 38 39 40 45 five in Europe, 41 43 44 47 48 three in Oceania, 32 33 46 and two in the United States. 1 42 Three studies reported on transmission between flats in apartment blocks, 38 39 40 two in quarantine hotels, 32 33 two in restaurants, 34 35 two in buses, 36 37 one in a food processing factory, 41 one in a courtroom, 43 one in an office, 44 one in a fitness facility, 42 one in a department store, 45 and four during singing events. 1 46 47 48 All the outbreaks occurred in 2020, except for one in January 2021 in South Korea 40 (before vaccine rollout started in this country) and one in July 2021 in a quarantine hotel in New Zealand.…”

“…Figure 2 provides details of the methodological quality ratings: three studies were rated as high quality, 33 35 46 five as medium quality, 32 34 36 41 47 and 10 as low quality. 1 37 38 39 40 42 43 44 45 48 These ratings represent the methodological quality of descriptive studies.…”

“…The other outbreaks identified in this review occurred in a food processing factory, 41 fitness facility, 42 courtroom, 43 office, 44 and department store. 45 …”

“…Sarti et al 44 (rated as low methodological quality) reported on an outbreak in an office in Italy in which five of six coworkers were identified as cases. One of the five coworkers was identified as the primary case, and transmission happened before symptom onset.…”