Estimation of seroprevalence and immunity of COVID-19 antibodies among children

The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2, has had a profound impact on global health and society. Understanding the dynamics of the virus's spread and its effects on different population segments is of utmost importance as the pandemic continues to evolve. While COVID-19 has predominantly affected adults, the susceptibility and role of children in its transmission have sparked significant interest and concern. The study aims to estimate the incidence of SARS-CoV-2 antibodies (Ab) in children. Also, to determine the naturally acquired immunity through examining recent and past infections of SARS-CoV-2 represented by the appearance of IgM and IgG antibodies in children. The study was conducted in Diyala, Iraq, from September 2022 to March 2023. During this time, a total of 180 samples were recorded and studied. The sample collected was divided into the patient group and the control group. The outcomes presented in this study provide a comprehensive comparative analysis between the patients and control groups regarding age, gender, and residence. Two age distribution classifications were used. The first one categorized the ages of the study groups into three groups. Statistical analysis showed a significant difference among these age categories (P=0.034). The second classification divided the age groups into fifteen segments, revealing another significant difference between the study groups (P=0.012). Moreover, the Mean ± SD in months within the control group showed a significantly higher value compared to the patient group, with values of (76.4 ± 51.7 vs. 49.7 ± 44.9, P = 0.0001), highlighting the age-based difference between the two groups. According to gender, the percentage of males within the patients' group was substantially higher when compared to that of the controls, with a proportion of (63.41% vs. 47.95%). Conversely, the percentage of females in the control group was notably higher compared to the patients' group, with figures of (52.04% vs. 36.58%, P= 0.038). Also, the findings revealed that the previous infection in children's families of the patient's group 63(76.8%) cases were significantly superior as compared with the control group 38 (38.8%) cases at P value (<0.0001). However, the findings showed that the number of cases infected with respiratory tract infection in the patient's group recorded 5(6.1%) cases, while 60(61.2%) no cases were monitored in the control group at P. value (<0.013). Specifically, the patient group exhibited markedly higher rates of several symptoms, including fever, sore throat, runny nose, rash, diarrhea, difficulty breathing, and coughing, compared to the control group (P<0.0001). Regarding the rate of anti-COVID-19 IgG, the results showed that out of 35 tested patients, 25 (74.28%) tested positive, while 9 (25.71%) tested negative. On the contrary, in the control group, among 74 healthy children who underwent testing, 56 (75.67%) were found to be positive, and 18 (24.32%) were negative for the antibody. Despite these variations, the difference between the two groups was statistically insignificant (P= 0.437). Regarding anti-COVID-19 IgM, the analysis revealed that among the 82 tested patients, 63 (76.82%) were positive, while 19 (23.17%) were negative. In contrast, among the 24 tested individuals in the control group, 8.33% were positive, and 91.66% were negative for the antibody. This resulted in a statistically significant distinction between the two groups, with a P-value of 0.0001. In conclusion, this study found that children with respiratory tract symptoms had a higher rate of positive COVID-19 infection compared to controls. It also highlighted that COVID-19 infection in children cannot be differentiated from other respiratory diseases based on symptoms. Additionally, approximately 10% of apparently healthy children were found to be asymptomatically infected with COVID-19. Furthermore, about 25% of patients and controls had protective immunity from previous infection or contact with positive cases.