Seroprevalence of SARS-Cov-2 IgG antibodies in patients at a single center in Saudi Arabia

BACKGROUND:
The coronavirus disease 2019 (COVID-19) pandemic has had a massive impact on public health as well as the economy. Understanding the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among undiagnosed individuals is important for developing an informed pandemic response.


OBJECTIVE:
Investigate the prevalence of undiagnosed COVID-19 disease.


DESIGN:
Cross-sectional.


SETTING:
Tertiary care center in Madinah, Saudi Arabia.


SUBJECTS AND METHODS:
All participants were on follow-up visits to various clinics and had not been previously diagnosed with COVID-19. Enzyme-linked immunosorbent assay was used to specifically assess the anti-spike IgG antibody seropositivity in serum samples. We associated the seropositivity rates of the participants with age, body mass index (BMI), nationality, blood groups, and sex with uni- and multivariate analyses.


MAIN OUTCOME MEASURES:
Seropositivity for IgG anti-spike antibodies against SARS-CoV-2.


SAMPLE SIZE AND CHARACTERISTICS:
527 subjects, with a median (interquartile percentiles) age of the 527 subjects was 34 (24–41).


RESULTS:

Of the 527 samples, about one-fourth (n=124, 23.5%) were positive for anti-spike IgG antibody against SARS CoV-2. Age was associated with anti-spike IgG antibody positivity (
P
<.002). Participants >30 years were more likely to be seropositive (28-29%) than younger participants (15.4%). Additionally, seropositivity was associated with female gender (
P
<.001) and a higher BMI (
P
<.006). In the multivariate logistic regression, age >30, female gender and BMI >40 were associated with seropositivity.



CONCLUSION:
The percentage of seropositive individuals reflects the high level of undiagnosed COVID-19 patients among the population. Our results will help in a better evaluation of the public health measures applied during the COVID-19 pandemic and any future public health crises.


LIMITATIONS:
Sample size was small, single-center study and no rural areas were included.


CONFLICT OF INTEREST:
None.