Introduction
During
the COVID-19 pandemic, a virological anomaly that garnered attention was
the persistent global prevalence of rhinoviruses (RV). The
non-pharmaceutical interventions implemented to mitigate SARS-CoV-2
transmission—such as mask-wearing, social distancing, and
lockdowns—resulted in a substantial reduction in the incidence of
respiratory viruses, including influenza, parainfluenza, respiratory
syncytial virus (RSV), and human metapneumovirus (hMPV)[1, 2]. However, in notable contradistinction, RV
demonstrated adaptability and appeared to coexist with SARS-CoV-2 at a
rate consistent with its typical seasonal patterns, despite the decrease
in interpersonal contacts due to these public health
measures[3]. RV is renowned for its efficient
transmission through both airborne particles and fomites. As
non-enveloped viruses, rhinoviruses exhibit prolonged survivability on
surfaces and resistance to disinfectants containing alcohol,
facilitating effective fomite transmission[4-6].
This characteristic likely played a pivotal role in the sustained
propagation of RV within populations, even in the face of various
pandemic measures such as masking, social distancing, and
lockdowns.
RV, commonly known as the ”common cold virus,” has historically been
overlooked as a causative agent of severe
illness[7]. Nevertheless, in recent years, the
clinical significance of RV has garnered considerable attention. Beyond
causing common colds, RV infections manifest in a spectrum of clinical
outcomes, ranging from asymptomatic infections to severe lower
respiratory conditions, including bronchiolitis, pneumonia, and asthma
exacerbations[8-10]. The diverse clinical
presentations of RV infections indicate a potential association between
illness severity and various host and environmental
factors[11]. Additionally, factors intrinsic to
the virus may influence the transition from asymptomatic infection to
severe illness. However, the complexity of this research is compounded
by RV’s status as the most diverse virus family within the enterovirus
genera. The current RV classification encompasses three species (RV-A,
RV-B, and RV-C), further divided into 169
subtypes[12]. Identifying the most clinically
relevant subtypes within this diversity is crucial for developing
targeted therapeutic strategies against this virus. Despite concerted
efforts, establishing meaningful connections between RV species as well
as subtypes and symptoms, seasonal patterns, severity, and interactions
with other viruses has proven challenging.
Following the extensive COVID-19 epidemic in February 2020, China
transitioned into a phase of normalized prevention and control measures
starting in May 2020[13]. Responding to the
heightened transmissibility of the Delta variant, China implemented a
novel strategy termed ”Dynamic COVID-zero” in August 2021. This
strategic approach encapsulates China’s accumulated knowledge in
effectively managing the Delta variant spread, aiming to control the
epidemic with heightened efficiency, reduced cost, and in a shorter
timeframe[14]. The core of this strategy lies in
the precise implementation of comprehensive measures to address
localized COVID-19 cases, swiftly sever the transmission chain, and
promptly terminate the epidemic[15].
However, in response to the emergence of the SARS-CoV-2 Omicron
subvariants, characterized by attenuated pathogenicity, coupled with the
broadening vaccination coverage, these stringent policies were lifted on
December 7, 2022. The abrupt shift in Non-Pharmaceutical Interventions
(NPIs), combined with the accrued ’immunity debt’ and viral evolution,
potentially contributed to the resurgence of other respiratory
viruses[16]. Notably, an outbreak of influenza A
virus among children was documented following the conclusion of the
zero-COVID policy in Shanghai, China[17]. Previous
research has indicated that viral interference among influenza virus,
rhinovirus, and other respiratory viruses can influence viral infections
at both the individual and population levels[18].
Hence, it becomes essential to closely monitor the alterations in the
pattern of RV infections post the ending of the zero-COVID policy.
This study investigates epidemiological shifts in RV infections among
children on Hainan Islands, with a focus on the periods before and after
the termination of the zero-COVID policy. Hainan, a tropical island
located at China’s southernmost tip, is known for its warm temperatures,
high humidity, and status as a major free trade port and tourist
destination. These unique climatic and geographical attributes
potentially present distinct health challenges. Specifically, the
research provides insights into how policy changes, notably the ending
of the zero-COVID policy, influenced the dynamics of respiratory viruses
from 2021 to 2023. The aim of this investigation is to enhance our
comprehension of RV circulation and associated diseases.