Urine-based immunoassay is a non-invasive method with demonstrated utility in detecting anti-SARS-CoV-2 antibodies in unvaccinated patients with COVID-19. To evaluate urine’s potential for serological surveys in a real-world setting, SARS-CoV-2 serology was performed on urine samples from vaccinated individuals, both with and without prior confirmed COVID-19. (1) Methods: An in-house indirect ELISA was used to measure antibodies against recombinant spike (S) and nucleocapsid (N) proteins of SARS-CoV-2 in urine and paired serum from 149 individuals vaccinated with Janssen AD26.COV2.S, an S protein-based COVID-19 vaccine. (2) Results: Anti-S and anti-N levels were higher in the urine and serum of participants with confirmed prior COVID-19 compared to those without prior infection. Urinary anti-S effectively distinguished vaccinated individuals with (AUC = 0.96) and without (AUC = 0.88) prior infection from negative controls (non-vaccinated, non-previously infected individuals) (p < 0.0001). Among vaccinated participants, urinary anti-S and anti-N identified prior infection, with AUC values of 0.73 (p < 0.0001) and 0.60 (p = 0.03), respectively, being recorded. (3) Conclusions: Findings indicate that urinary anti-SARS-CoV-2 antibodies reflect AD26.COV2.S vaccination and previous COVID-19. To further advance the methodology, studies with larger sample sizes and a greater diversity of COVID-19 vaccines are required.

Urine is a non-invasive sample that has been proven useful in the detection of anti-SARS-CoV-2 antibodies in patients with COVID-19. To assess the potential of urine for serological surveys in a real-world scenario, we performed SARS-CoV-2 serology on urine samples from vaccinated individuals, with and without prior confirmed COVID-19. Methods: Using an in-house indirect ELISA, we measured IgG against recombinant Spike (S) and Nucleocapsid (N) proteins of SARS-CoV-2 in the urine and paired serum from 149 individuals vaccinated with AD26.COV2.S, an S protein-based COVID-19 vaccine. Results: Anti-S and anti-N IgG were higher in the urine and serum of participants with confirmed prior COVID-19 when compared to those without previous infection. Urinary anti-S effectively distinguished vaccinated individuals with (AUC=0.96) and without (AUC=0.88) prior infection from negative controls (non-vaccinated, non-previously infected individuals) (p<0.0001). Among vaccinated participants, urinary anti-S and anti-N identified previous infection with AUC of 0.73 (p<0.0001) and 0.60 (p=0.03), respectively. Conclusion: Our findings demonstrate that urinary anti-SARS-CoV-2 reflect vaccination and previous COVID-19. We highlight the potential of urine as a convenient sample in the initial clinical and epidemiological management of possible new epidemics.