Abstract
Background COVID-19 is an ongoing pandemic posing a big threat to public
health and economy. Novel variants are constantly emerging with
different transmissibility and pathogenicity. This study aimed to
explore the hematological characteristics of COVID-19 delta variant
during the outbreak in July 2021, Nanjing. Methods This study
retrospectively analyzed demographic and clinical parameters of 80
patients diagnosed with COVID-19 delta variant infection. Patients were
classified into mild, moderate and severe/critical group according to
the guideline. Characteristics of each group were compared. Results The
percentage of elderly and patients with comorbidities was significantly
higher in the severe/critical group. Vaccination rate was significantly
lower in this group. Decreased lymphocyte number, especially CD4+ and
CD8+ T cells, elevated fibrinogen, CRP, PCT and IL-6 were associated
with disease severity (P<0.05). Severe or critical cases
tended to have higher viral load shown by lower CT values of ORF1ab and
N gene (P=0.08, P=0.06) and lower specific IgG antibody level (P=0.15)
but it did not reach statistical significance. Conclusions Increasing
vaccination rate in the elderly and population with comorbidities might
improve the prognosis of COVID-19 delta variant. Mechanism study of
immune evasion of COVID-19 and methods to booster our immune system was
urgently needed.