**4. Discussion**

The aim of this study was to assess the SARS-CoV-2 seroprevalence, after the first wave of the disease, among GPs working in Catania province (Italy). Probable cases, according to WHO criteria [12], were 21 (20%). Serological analysis revealed a low seroprevalence (3%) among GPs.

These low seroprevalence rates were found despite the treatment of 777 patients with COVID-19 infections during the first wave [11] period in which GPs worked with very few PPE available from the local health authority. Nevertheless, the degree of contagion was lower in GPs compared to HCWs in direct contact with COVID-19 patients in hospital settings. Other seroprevalence studies carried out among HCWs working in hospital report higher rates of prevalence: Belgium (12.6%) [13], Spain (11.2%) [14], Italy (14.4%) [15], Sweden (19.1%) [16], the United Kingdom (10.8–43.5%) [13,17], and the United States of America (7.6–13.7%) [18,19]. The differences in these rates may be due to differences in seroprevalence in the general population by May 2020: 8.0% in Belgium, 5.5% in Spain, 4.6% in Italy, 3.7% in Sweden, 5.1% in the United Kingdom, and only 0.85% in Germany [20].

A recent study on duration of SARS-CoV-2 antibody carried out by Lumley et al. [21] evidences that anti-spike IgG levels remained stably detected after a positive result in 94% of health care workers after 180 days, instead anti-nucleocapsid IgG levels rose to a peak at 24 and the mean estimated antibody half-life was 85 days. Ongoing longitudinal studies are required to track the long-term duration of antibody levels and their association with immunity to SARS-CoV-2 reinfection and evaluate these two IgG fractions for guide vaccination modalities.

To date, no seroprevalence studies have been carried out among GPs by other research groups.

Due to the type of work and the shortage of PPE, GPs contracted the virus at the beginning of the spread of SARS-CoV-2. Subsequently, distancing rules were also adopted within clinics, and overnight stays and contact were avoided unless requested. Thus, contagion was able to be reduced.

It is has been found that rigorous use of appropriate PPE by HCWs when providing direct care of all patients efficiently prevents COVID-19 transmission [22,23]. Moreover, a study carried out by Brehm underlines that mindfulness of COVID-19 is crucial even when suitable PPE is used.

Our results are in line with an investigation carried out by Arons [24], which proved that pre-symptomatic patients play a crucial role in the spread of SARS-CoV-2 associated with both community and healthcare facilities.

It is important to finalize strategies and procedures to prevent SARS-CoV-2 infection among GPs, for example, specific guidelines for GPs to safely guarantee care for patients during the spread of COVID-19. Another input could be the introduction of telemedicine procedures to reduce direct contact with patients [10,25–27].

In conclusion, the low seroprevalence highlighted in these results can be attributed to correct managemen<sup>t</sup> of patients by GPs during the first wave. It is now hoped that mass vaccination, in combination with appropriate behavior and use of PPE, can help further reduce the risk of COVID-19 disease.

**Author Contributions:** Conceptualization, C.L. and V.R.; methodology, G.P.; validation, C.L., V.R. and M.T.L.; formal analysis C.L. and M.T.L.; investigation, C.L.; data curation, C.L. and F.C.; writing— original draft preparation, F.C.; writing—review and editing, C.L.; supervision, V.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of Catania 1 (n. 54/2020).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** Data available on request due to privacy restrictions.

**Conflicts of Interest:** The authors declare no conflict of interest.
