SARS-CoV-2 may pose an occupational health risk to healthcare workers. Here, we report the seroprevalence of SARS-CoV-2 antibodies, self-reported symptoms and occupational exposure to SARS-CoV-2 among healthcare workers at a large acute care hospital in Sweden. The seroprevalence of IgG antibodies against SARS-CoV-2 was 19.1% among the 2149 healthcare workers recruited between April 14th and May 8th 2020, which was higher than the reported regional seroprevalence during the same time period. Symptoms associated with seroprevalence were anosmia (odds ratio (OR) 28.4, 95% CI 20.6–39.5) and ageusia (OR 19.2, 95% CI 14.3–26.1). Seroprevalence was also associated with patient contact (OR 2.9, 95% CI 1.9–4.5) and covid-19 patient contact (OR 3.3, 95% CI 2.2–5.3). These findings imply an occupational risk for SARS-CoV-2 infection among healthcare workers. Continued measures are warranted to assure healthcare workers safety and reduce transmission from healthcare workers to patients and to the community.

Background Emerging data support detectable immune responses for months after severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection and vaccination, but it is not yet established to what degree and for how long protection against reinfection lasts. Methods We investigated SARS‐CoV‐2‐specific humoral and cellular immune responses more than 8 months post‐asymptomatic, mild and severe infection in a cohort of 1884 healthcare workers (HCW) and 51 hospitalized COVID‐19 patients. Possible protection against SARS‐CoV‐2 reinfection was analyzed by a weekly 3‐month polymerase chain reaction (PCR) screening of 252 HCW that had seroconverted 7 months prior to start of screening and 48 HCW that had remained seronegative at multiple time points. Results All COVID‐19 patients and 96% (355/370) of HCW who were anti‐spike IgG positive at inclusion remained anti‐spike IgG positive at the 8‐month follow‐up. Circulating SARS‐CoV‐2‐specific memory T cell responses were detected in 88% (45/51) of COVID‐19 patients and in 63% (233/370) of seropositive HCW. The cumulative incidence of PCR‐confirmed SARS‐CoV‐2 infection was 1% (3/252) among anti‐spike IgG positive HCW (0.13 cases per 100 weeks at risk) compared to 23% (11/48) among anti‐spike IgG negative HCW (2.78 cases per 100 weeks at risk), resulting in a protective effect of 95.2% (95% CI 81.9%–99.1%). Conclusions The vast majority of anti‐spike IgG positive individuals remain anti‐spike IgG positive for at least 8 months regardless of initial COVID‐19 disease severity. The presence of anti‐spike IgG antibodies is associated with a substantially reduced risk of reinfection up to 9 months following asymptomatic to mild COVID‐19.

Apart from the well-defined factors in neuronal cells 1 , only few reports consider that variability of sporadic ALS progression can depend on the less-defined contributions from glia 2,3 and blood vessels 4 .In this study we use an expression weighted cell-type enrichment method to infer cell activity in spinal cord samples from sporadic ALS patients and mouse models of this disease. Here we report that sporadic ALS patients present cell activity patterns consistent with two mouse models in which enrichments of vascular cell genes preceded the microglial response. Notably, during the presymptomatic stage, perivascular fibroblast cells showed the strongest gene enrichments and their marker proteins SPP1 and COL6A1 accumulated in enlarged perivascular spaces in sporadic ALS patients. Moreover, in plasma of 574 ALS patients from four independent cohorts, increased levels of SPP1 at disease diagnosis repeatedly predicted shorter survival with stronger effect than the established risk factors of bulbar onset or neurofilament levels in cerebrospinal fluid. We propose that the activity of the recently-discovered perivascular fibroblast can predict ALS patient survival and provide a novel conceptual framework to re-evaluate definitions of ALS etiology.