3.3 Allergic and immune status of children with SARS-CoV-2
infection
As shown in Table 2, the most common allergic disease was allergic
rhinitis (36, 83.7%), followed by atopic dermatitis, food allergy,
asthma and urticaria. Only one child, a 13-year-old boy, was previously
diagnosed with asthma. Ten (23.3%) children had self-reported allergy
to drugs, all of which were penicillin. Among allergic children, 9
(20.9%) had more than one kind of allergic diseases. Other few reported
allergens included dust mites, eggs and mangos, each in one child.
In comparison of COVID-19-related measurements between allergic and
non-allergic children, no statistical difference was found in the
demographics, clinical features and disease course (Table 1). Blood cell
counts and biochemical results were mostly similar between two groups,
except that eosinophils counts, and serum levels of PCT, D-dimer and AST
were lower in allergic group (p < 0.05), but these
measurements were all in normal ranges, without clinical relevance
(Table 3).
Serum total IgE level of allergic children was higher than that of
non-allergic individuals (median, 46.30 vs 28.75, unit of IU/ml, p =
0.048), and allergic children had greater percentage of increased IgE
(42.4% vs 29.3%, p = 0.155) without statistical difference. In
general, all of the tested immunological parameters were not different
between these two groups (p > 0.05), including
immunoglobulins, complements and cytokines (Table 4).
The lymphocyte subsets were not found significantly different between
the allergic and non-allergic COVID-19 children (Table 4), as well as
between patients with and without pneumonia (Table 6). The results of
correlation analysis between immunological parameters were displayed in
Figure 3. There appeared three clusters of correlations. The first one
is lymphocyte, total T cells, CD4+ and CD8+ T cells as well as B cells
and NK cells. This correlation was relatively strong in all patients
including the allergic group and pneumonia group. The second correlation
was in total IgG, IgM, IgA, IgE, C3 and C4 levels. It was relatively
stronger in pneumonia group whereas the correlations within this cluster
decreased in allergy group. Immunoglobulin levels and lymphocyte subsets
showed a negative correlation within all patients and pneumonia group.
The third cluster was between the analyzed cytokines, which showed a
stronger correlation between each other in pneumonia group. In addition,
the duration of hospitalization was positively correlated with the time
of RT-PCR conversion, but these two temporal indices had no significant
correlation with immunological and inflammatory measurements, except for
the slightly negative correlation between the duration of
hospitalization and the level of IFN-γ in patients with pneumonia
(r = -0.276) (Figure 4).