DISCUSSION
A common national registry of children with SARS-CoV-2 aims to assess
more accurately whether cancer leads to more severe COVID-19. In our
analysis, severe COVID-19 was more frequently detected in children
without comorbidities (15%) than in children with cancer (7,1%),
except in the case of recent alloHSCT (35.7%), as other studies
reflected (8,12), but unrelated to the date of HSCT.
Despite a mild cancer course in children, the mortality rate is 1.6%,
which, in our records, is associated with recent alloHSCT or other
comorbidities. These rate is similar to the global GRCCC study (2),
although with lower mortality (3.8%), probably because our patient’s
data are located in a high-income country and during periods where less
severe variants were included (13). Indeed, we found a milder infection,
although not statistically significant, in the later phases of the
pandemic and in vaccinated patients (14–16), and no deaths were
recorded among them. Additionally, other comorbidities increased the
severity in patients with cancer, although their impact was less than in
patients without oncological diseases. Chemotherapy and radiation
therapy did not seem to be related to clinical severity (17).
Nosocomial transmission was higher among children with cancer (11,2% vs
0,8%, p<0,001) , probably due to more frequent hospital
visits. However, school transmission rates were similar between children
with and without cancer, which may be useful to avoid changing the
schooling plan of patients.
Study limitations of selection bias need to be acknowledged, since the
initial screening policies in pediatric oncology units could result in a
higher registration of mild cases. However, there were no reported cases
requiring oxygen or admission to intensive care units in patients with
ALL in maintenance, which highlights the mildness of COVID-19 in this
population (18,19).
In conclusion, our data show that the infection is not more severe in
patients with cancer/alloHSCT, except in patients with recent alloHSCT
or additional comorbidities. These data support, in high-income
countries, a policy of infection management similar to that with other
respiratory viral infections in cancer pediatric patients, directed by
the patient’s clinical status or other comorbidities rather than by
isolation of SARS-CoV-2.