Serological Patterns of SARS-CoV-2 Infection and Their Association with Age, Sex, and Clinical Severity in Kirkuk, Iraq

Sooz Samad Abdulrahman

doi:10.51699/cajmns.v7i4.3384

Authors

Sooz Samad Abdulrahman Department of Health Community, College of Health and Medical Technologies, Babagurgur University

DOI:

https://doi.org/10.51699/cajmns.v7i4.3384

Keywords:

SARS-CoV-2, Serological profiles, IgM antibodies, IgG antibodies, Clinical severity

Abstract

Background: SARS-CoV-2 infection shows variable serological responses influenced by demographic and clinical factors, highlighting the importance of understanding antibody patterns across different patient groups. Aims of the study: This study aimed to evaluate SARS-CoV-2 serological patterns and determine their associations with age, sex, and clinical severity among individuals in Kirkuk, Iraq. Methodology: This study included 130 participants recruited from outpatient, inpatient, intensive, and respiratory care units at Kirkuk Medical City, Iraq, between August and December 2021. Demographic and clinical data were collected using a structured questionnaire. COVID-19 manifestations and severity were assessed by specialized physicians according to WHO criteria, incorporating symptoms, radiographic findings, and oxygen saturation. SARS-CoV-2-specific IgM and IgG antibodies were evaluated using serological immunoassays and the STANDARD Q COVID-19 IgM/IgG Duo Test, with antibody levels ≥10 AU/mL considered positive. Result: Among 130 participants, 41 (31.5%) had IgM-associated recent infection, 28 (21.5%) had IgG-associated previous infection, and 61 (46.9%) were seronegative. Females predominated in the IgM group (56.1%), whereas males predominated in the IgG group (71.4%). Mean age was higher in the IgM than IgG group (51.6 vs. 43.7 years). Most IgM-positive participants were ≥50 years (61.0%), while 75.0% of IgG-positive participants were aged 30–59 years. Among IgM-positive cases, 73.2% had moderate and 26.8% severe COVID-19. Conclusions: SARS-CoV-2 serological profiles varied according to age, sex, and clinical severity. IgM-associated recent infection was more frequent among older participants and females, while IgG-associated previous infection predominated among males and middle-aged individuals, highlighting distinct demographic and clinical patterns.

References

B. Hu, H. Guo, P. Zhou, and Z.-L. Shi, “Characteristics of SARS-CoV-2 and COVID-19,” Nature Reviews Microbiology, vol. 19, no. 3, pp. 141–154, 2021, doi: 10.1038/s41579-020-00459-7.

R. Ochani, A. Asad, F. Yasmin, S. Shaikh, H. Khalid, S. Batra, et al., “COVID-19 pandemic: From origins to outcomes,” Annals of Medicine and Surgery, vol. 64, Art. no. 102173, 2021, doi: 10.1016/j.amsu.2021.102173.

M. Chvatal-Medina, Y. Mendez-Cortina, P. J. Patiño, P. A. Velilla, and M. T. Rugeles, “Antibody responses in COVID-19: A review,” Frontiers in Immunology, vol. 12, Art. no. 633184, 2021, doi: 10.3389/fimmu.2021.633184.

F. N. Zervou, P. Louie, A. Stachel, I. M. Zacharioudakis, Y. Ortiz-Mendez, K. Thomas, et al., “IgA correlates with severity of disease in early COVID-19 infection,” Journal of Medical Virology, vol. 93, no. 9, pp. 5408–5415, 2021, doi: 10.1002/jmv.27058.

K. Vanshylla, V. Di Cristanziano, F. Kleipass, F. Dewald, P. Schommers, L. Gieselmann, et al., “Kinetics and correlates of the neutralizing antibody response to SARS-CoV-2 infection in humans,” Cell Host & Microbe, vol. 29, no. 6, pp. 917–929.e4, 2021, doi: 10.1016/j.chom.2021.04.015.

I. Bergeri, M. G. Whelan, H. Ware, L. Subissi, A. Nardone, H. C. Lewis, et al., “Global SARS-CoV-2 seroprevalence from January 2020 to April 2022: A systematic review and meta-analysis of standardized population-based studies,” PLoS Medicine, vol. 19, no. 11, Art. no. e1004107, 2022, doi: 10.1371/journal.pmed.1004107.

N. Bobrovitz, R. K. Arora, C. Cao, E. Boucher, M. Liu, C. Donnici, et al., “Global seroprevalence of SARS-CoV-2 antibodies: A systematic review and meta-analysis,” PLoS ONE, vol. 16, no. 6, Art. no. e0252617, 2021, doi: 10.1371/journal.pone.0252617.

K. Colwill, Y. Galipeau, M. Stuible, C. Gervais, C. Arnold, B. Rathod, et al., “A scalable serology solution for profiling humoral immune responses to SARS-CoV-2 infection and vaccination,” Nature Microbiology, vol. 7, no. 6, pp. 782–795, 2022, doi: 10.1038/s41564-022-01111-3.

D. Wilkins, A. A. Aksyuk, A. Ruzin, K. M. Tuffy, T. Green, R. Greway, et al., “Validation and performance of a multiplex serology assay to quantify SARS-CoV-2 antibodies,” Journal of Immunological Methods, vol. 505, Art. no. 113253, 2022, doi: 10.1016/j.jim.2022.113253.

T. Niedrist, T. Perkmann, T. Koller, E. Puchhammer-Stöckl, H. Laferl, L. Weidner, et al., “Longitudinal comparison of automated SARS-CoV-2 serology assays in assessing virus- and vaccine-induced antibodies,” Clinical Chemistry and Laboratory Medicine, vol. 60, no. 5, pp. 736–745, 2022.

A. Atti, M. Ferrari, J. Castillo-Olivares, P. Monk, R. Gopal, M. Patel, et al., “Antibody correlates of protection from SARS-CoV-2 reinfection prior to vaccination: A nested case-control study,” The Lancet Microbe, vol. 3, no. 8, pp. e580–e590, 2022.

L. E. Gentles, L. Kehoe, K. H. D. Crawford, K. Lacombe, J. A. Dickerson, C. R. Wolf, et al., “Dynamics of infection-elicited SARS-CoV-2 antibodies in children over time,” JCI Insight, vol. 7, no. 6, Art. no. e155323, 2022.

A. Booth, A. B. Reed, S. Ponzo, A. Yassaee, M. Aral, D. Plans, et al., “Population risk factors for severe disease and mortality in COVID-19: A global systematic review and meta-analysis,” PLoS ONE, vol. 16, no. 3, Art. no. e0247461, 2021, doi: 10.1371/journal.pone.0247461.

J. Fabião, B. Sassi, E. F. Pedrollo, F. Gerchman, C. K. Kramer, C. B. Leitão, et al., “Why do men have worse COVID-19-related outcomes? A systematic review and meta-analysis with sex-adjusted for age,” Brazilian Journal of Medical and Biological Research, vol. 55, Art. no. e11711, 2022, doi: 10.1590/1414-431X2021e11711.

S. Magesh, D. John, W. T. Li, Y. Li, A. Mattingly-App, S. Jain, et al., “Disparities in COVID-19 outcomes by race, ethnicity, and socioeconomic status: A systematic review and meta-analysis,” JAMA Network Open, vol. 4, no. 11, Art. no. e2134147, 2021, doi: 10.1001/jamanetworkopen.2021.34147.

A. Vaughan, E. F. Duffell, G. S. Friedl, P. Waight, S. N. Ladhani, N. Andrews, et al., “Systematic review of SARS-CoV-2 seroprevalence studies in the WHO European Region,” BMJ Open, vol. 13, no. 11, Art. no. e064240, 2023, doi: 10.1136/bmjopen-2022-064240.

N. R. Hussein, G. H. Shahab, N. A. Rasheed, A. N. Ahmed, R. S. Salih, A. S. Mahdi, et al., “A study of anti-SARS-CoV-2 antibody positivity in Duhok City, Iraq,” Journal of Infection in Developing Countries, vol. 17, no. 7, pp. 937–943, 2023, doi: 10.3855/jidc.17518.

V. Loria, M. E. Ramirez-Cardich, A. M. Zamora, et al., “Cohort profile: Evaluation of immune response and population prevalence of SARS-CoV-2 infection and vaccination—the RESPIRA cohort,” BMJ Open, vol. 13, no. 12, Art. no. e071284, 2023, doi: 10.1136/bmjopen-2022-071284.

M. A. Alsamarai, A. H. Alobaidi, A. Kayabaş Avşar, and A. M. Alsamarai, “COVID-19 immune status in the general population in Kirkuk Province, Iraq,” Coronaviruses, vol. 7, published online Dec. 3, 2025.

Y. Zhou, F. Pei, M. Ji, L. Wang, H. Zhao, H. Li, et al., “Advancements in detection of SARS-CoV-2 infection for confronting COVID-19 pandemics,” Laboratory Investigation, vol. 102, no. 1, pp. 4–13, 2022, doi: 10.1038/s41374-021-00663-w.

A. E. Taha, Z. M. Al-Khafaji, W. M. Al-Wattar, et al., “Estimation of anti-SARS-CoV-2 IgM/IgG seroprevalence and associated factors,” Medicine, vol. 104, Art. no. e42039, 2025.

K. S. Lone, S. M. Khan, M. A. Qurieshi, et al., “Seroprevalence of SARS-CoV-2-specific anti-spike IgM and IgG antibodies in a population-based sample,” Frontiers in Public Health, vol. 10, Art. no. 967447, 2022, doi: 10.3389/fpubh.2022.967447.

I. Kučinskaitė-Kodzė, M. Simanavičius, A. Šimaitis, et al., “Persistence of SARS-CoV-2-specific antibodies for 13 months after infection,” Viruses, vol. 13, no. 11, Art. no. 2313, 2021, doi: 10.3390/v13112313.

X. Yan, G. Chen, Z. Jin, et al., “Persistence of anti-SARS-CoV-2 IgM in convalescent COVID-19 patients,” Journal of Infection, vol. 84, no. 1, pp. 94–118, 2021.

Y. Kobashi, Y. Shimazu, Y. Nishikawa, T. Kawamura, T. Kodama, D. Obara, et al., “The difference between IgM and IgG antibody prevalence in different serological assays for COVID-19: Lessons from the examination of healthcare workers,” International Immunopharmacology, vol. 92, Art. no. 107360, 2021, doi: 10.1016/j.intimp.2020.107360.

J. Fröberg, J. Gillard, R. Philipsen, et al., “SARS-CoV-2 mucosal antibody development and persistence and their relation to viral load and COVID-19 symptoms,” Nature Communications, vol. 12, Art. no. 5621, 2021, doi: 10.1038/s41467-021-25949-x.

L. J. Akinbami, D. Kruszon-Moran, C. Wang, et al., “SARS-CoV-2 serology and self-reported infection among adults—National Health and Nutrition Examination Survey, United States, August 2021–May 2022,” MMWR Morbidity and Mortality Weekly Report, vol. 71, no. 48, pp. 1522–1525, 2022, doi: 10.15585/mmwr.mm7148a4.

A. Y. Saeed, N. R. Hussein, I. A. Naqid, et al., “Seroprevalence of SARS-CoV-2 IgG/IgM antibodies among patients in Zakho City, Kurdistan Region, Iraq,” Journal of Infection in Developing Countries, vol. 16, pp. 1126–1131, 2022.

I. M. Al-Osta, O. El-Bakoush, H. El-Maghrahi, et al., “The seroprevalence of IgM and IgG antibody production against SARS-CoV-2 according to age and sex,” Pharmacy & Pharmacology International Journal, 2024, doi: 10.5281/zenodo.10946622.

Z. O. Khudhur, H. Omer, S. S. Qader, et al., “Comparative study of SARS-CoV-2 antibody titers between male and female COVID-19 patients living in the Kurdistan Region of Iraq,” Eurasian Journal of Medical Oncology, 2021.

Y. I. Kim, S. M. Kim, S. J. Park, et al., “Kinetics of neutralizing antibodies against SARS-CoV-2 infection according to sex, age, and disease severity,” Scientific Reports, vol. 12, Art. no. 13491, 2022, doi: 10.1038/s41598-022-17605-1.

C. G. Arnold, A. Libby, A. Vest, A. Hopkinson, and A. A. Monte, “Immune mechanisms associated with sex-based differences in severe COVID-19 clinical outcomes,” Biology of Sex Differences, vol. 13, Art. no. 7, 2022, doi: 10.1186/s13293-022-00417-3.

B. Zhai, J. Clarke, B. A. Agostini, et al., “SARS-CoV-2 antibody response is associated with age and body mass index in convalescent outpatients,” Journal of Immunology, vol. 208, pp. 1712–1720, 2022.

P. Zimmermann and N. Curtis, “Why does the severity of COVID-19 differ with age? Understanding the mechanisms underlying the age gradient in outcome following SARS-CoV-2 infection,” Pediatric Infectious Disease Journal, vol. 41, no. 2, pp. e36–e45, 2022, doi: 10.1097/INF.0000000000003413.

A. Solastie, C. Virta, A. Haveri, et al., “Changes in SARS-CoV-2 seroprevalence and population immunity in Finland during 2020–2022,” Emerging Microbes & Infections, vol. 12, no. 2, Art. no. 2222849, 2023, doi: 10.1080/22221751.2023.2222849.

J. K. Baillie, et al., “SARS-CoV-2 antibody responses associate with sex, age, and disease severity,” Nature Communications, 2023.

T. D. Pham, C. Huang, O. F. Wirz, et al., “Seroprevalence of SARS-CoV-2 among high-density communities and associated risk factors,” Emerging Infectious Diseases, vol. 28, no. 3, pp. 554–563, 2022.