Prevalence and Longevity of SARS-CoV-2 Antibodies Among Health Care Workers

Seroprevalence and longevity of SARS-CoV-2 nucleocapsid antigen-IgG among health care workers in a large COVID-19 public hospital in Saudi Arabia: A prospective cohort study

Seroprevalence of SARS-CoV-2 IgG among health care workers (HCWs) is crucial to inform infection control programs. Conflicting reports have emerged on the longevity of SARS-CoV-2 IgG. Our objective is to describe the prevalence of SARS-CoV-2 IgG in HCWs and perform 8 months longitudinal follow-up (FU) to assess the duration of detectable IgG. In addition, we aim to explore the risk factors associated with positive SARS-CoV-2 IgG. The study was conducted at a large COVID-19 public hospital in Riyadh, Saudi Arabia. All HCWs were recruited by social media platform. The SARS-CoV-2 IgG assay against SARS-CoV-2 nucleocapsid antigen was used. Multivariable logistic regression was used to examine association between IgG seropositive status and clinical and epidemiological factors. A total of 2528 (33% of the 7737 eligible HCWs) participated in the survey and 2523 underwent baseline serological testing in June 2020. The largest occupation groups sampled were nurses [n = 1351(18%)], physicians [n = 456 (6%)], administrators [n = 277 (3.6%)], allied HCWs [n = 205(3%)], pharmacists [n = 95(1.2%)], respiratory therapists [n = 40(0.5%)], infection control staff [n = 21(0.27%], and others [n = 83 (1%)]. The total cohort median age was 36 (31–43) years and 66.3% were females. 273 were IgG seropositive at baseline with a seroprevalence of 10.8% 95% CI (9.6%-12.1%). 165/185 and 44/112 were persistently IgG positive, at 2–3 months and 6 months FU respectively. The median (25^th– 75^th percentile) IgG level at the 3 different time points was 5.86 (3.57–7.04), 3.91 (2.46–5.38), 2.52 (1.80–3.99) respectively. Respiratory therapists OR 2.38, (P = 0.035), and those with hypertension OR = 1.86, (P = 0.009) were more likely to be seropositive. A high proportion of seropositive staff had prior symptoms 214/273(78%), prior anosmia was associated with the presence of antibodies, with an odds ratio of 9.25 (P<0.001), as well as fever and cough. Being a non-smoker, non-Saudi, and previously diagnosed with COVID-19 infection by PCR were statistically significantly different by seroprevalence status. We found that the seroprevalence of IgG against SARS-CoV-2 nucleocapsid antigen was 10.8% in HCWs at the peak of the pandemic in Saudi Arabia. We also observed a decreasing temporal trend of IgG seropositivity over 8 months follow up period.

Self-Administered, Remote Assessment of SARS-CoV-2 Seroprevalence in Health Care Workers

Background

Our objective was to safely and remotely assess longitudinal SARS-CoV-2 seroprevalence in at-risk health care workers at the onset of the epidemic.

Methods

Self-administered serologic testing was performed every 30 days up to 5 times using a point-of-care, lateral flow SARS-CoV-2 nucleocapsid IgG immunoassay in a cohort of at-risk health care workers (n = 339) and lower-risk controls (n = 100).

Results

Subjects were enrolled between 4/14/20–5/6/20 and most were clinicians (41%) or nurses (27%). Of 20 subjects who reported confirmed SARS-CoV-2 infection prior to (n = 5, 1%) or during the study (n = 15, 3%), half (10/20) were seropositive. Five additional subjects were seropositive and did not report documented infection. Estimated infection rates in health care workers did not differ from concurrent community rates.

Conclusions

This remotely conducted, contact-free study did not identify serologic evidence of widespread occupational SARS-CoV-2 infection in health care workers.