Is leukopenia and lymphopenia a characteristic feature of COVID-19 in children?

To analyze whether leucopenia and lymphopenia a characteristic feature of children with COVID-19 and to find out its association with the disease severity.

This was a descriptive cross-sectional study conducted at The Children's Hospital Lahore from March 2020 to October 2020. All confirmed cases of COVID-19 infection and post-COVID MIS-C/Kawasaki Disease diagnosed on the basis of RT-PCR and Antibody test respectively were included. Complete blood and differential counts were performed on the day of admission.

Out of a total of 83 patients 60 (72%) were diagnosed as COVID-19 and 23 (28%) as post-COVID MIS-C/KD. The mean age of children was 7.0±4.3 years (95%CI: 6.07 - 8.75) with a male preponderance 51 (61%). Twenty (24%) children had an underlying comorbidity and 7 (8%) were surgical cases. Our case fatality rate was 5 (6%) and all children who died had an underlying comorbid condition. In both, COVID and MIS-C/KD the mean leukocyte count was (14.0 ± 12.5 vs 13.6 ± 6.9 x10⁹/L), respectively (p=0.888). The mean lymphocyte count in children with COVID was (39.1 ± 21.4%). Patients with MIS-C/KD showed significantly higher levels of neutrophil count (76.5 ± 15.0%) as compared to children with COVID (52.0 ± 22.1%), absolute lymphocyte count was (5.02±4.81 vs 2.13±0.95 x10⁹/L) in COVID and MIS-C respectively (p=<0.001). In 60 COVID-19 patients, the mean neutrophil lymphocyte ratio (NLR) in mild-moderate and severe-critical group was 2.00 and 5.08 respectively (p=0.009).

The blood picture of COVID-19 in children does not show leukopenia. NLR was a prognostic factor to assess the severity in COVID-19 patients. The presence of an underlying comorbid conditions is significant a risk factor for poor outcome.