1 Introduction
Acute respiratory tract infections (ARTIs) remain one of the most common
major public health threats1. According to the data of
the main causes of death in the world released by the World Health
Organization, Lower Respiratory Tract Infections (LRTIs) ranks fourth in
the world and ranks first in low-income countries2.
Viral infections are the most frequent cause of
ARTIs3. Since HMPV was first discovered in 2001 in the
Netherland and has been detected in other countries, it has been
determined to be one of the main pathogens of ARTIs in children,
immunocompromised people and the elderly4,5. As a
member of the Metapneumovirus genus of the Pneumoviridae
family6, HMPV genome is a negative-sense
single-stranded RNA molecule, 13Kb long, composed of eight genes
encoding nine proteins: 3′-N, P , M, F, M2-1/M2-2, SH, G,
L-5′7. Based upon the sequence variability of the
attachment (G) and fusion (F) surface glycoproteins, HMPV can be divided
into four subtypes (A1, A2, B1 and B2). The A2 subgroup is the most
genetically heterogeneous of the four subgroups and some studies have
suggested its further sub-division into A2a, A2b1 and A2b2(A2c)
sub-lineages based on sequence data7-9. It is well
known that these 2 main subgroups are prevalent around the world and
that major HMPV subtypes switch every year10-12.
However, it is questionable whether there is an association between
genotype and disease severity.
Since late 2019, severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2) was discovered in Wuhan, China, it has caused a huge
economic and health burden worldwide. To prevent the spread of the
virus, large-scale non-pharmaceutical interventions have been
implemented in China, including working from home, online teaching,
mandatory wearing of masks in public places, social distancing, and hand
hygiene. Reductions in influenza and respiratory syncytial virus cases
under these interventions have been reported in many countries, yet few
studies have examined changes in HMPV cases during
outbreaks13-17. The purpose of this study was to
evaluate the epidemiological, clinical, and molecular characteristics of
HMPV infections occurring among hospitalized children with ARTIs in
China from April 2018–March 2019. In addition, this study explored the
impact of the COVID-19 pandemic on
HMPV infection.