Background: Studies on age-related differences in clinical and
laboratory features on coronavirus disease 2019 (COVID-19) are limited.
We aimed to evaluate the demographic, clinical, and laboratory findings
of COVID-19 in children younger than six months old and compare them
with older children. Methods: A single-center retrospective study,
including 209 confirmed COVID-19 cases, was conducted between March 11,
2020, and September 1, 2021. The case group consisted of 47 patients
younger than six months old, and the control group consisted of 162
patients older than six months old. Results: The mean age of the case
group was 2.77±1.52 months, and the control group was 101.89±65.77
months. Cough was statistically higher in the control group, poor
feeding was higher in the case group (P=.043, .010). The underlying
disease ratio was statistically higher in the case group; however, the
hospitalization rate was higher in the case group (P=.001, .036). The
case group had significantly lower median values of the absolute
neutrophil count, hemoglobin, and higher median values of white blood
cell, absolute lymphocyte count, platelet than the control group
(P<.05). C-reactive protein, fibrinogen values were
significantly lower, and procalcitonin, D-dimer, troponin T, N‑terminal
pro-B-type natriuretic peptide significantly higher in the case group
(P<.05). Lymphopenia was more common in the control group,
whereas neutropenia was more common in the case group (P= .001, .011).
Conclusions: We showed that most children younger than six months old
had mild and asymptomatic COVID-19; however, the hospitalization rate
was higher, and neutropenia was more common than older children.