Acute conjunctivitis caused mainly by viral pathogens is an extremely frequent ophthalmological disease in people of all ages [1]. Viral conjunctivitis involves various infectious diseases, among which acute hemorrhage conjunctivitis (AHC), epidemic keratoconjunctivitis (EKC) and pharyngoconjunctival fever (PCF) are the three common diseases [2]. AHC is characterized by the sudden onset of ocular pain, swelling of the eyelids, a "foreignbody" sensation or irritation, epiphora (excessive tearing), eye discharge, and photophobia [1]. The typic symptoms of EKC include bulbar conjunctival reddening, foreignbody feeling, photophobia and tearing, and EKC frequently complicates with pseudomembranes [3]. PCF is an acute and highly contagious disease characterized by fever, pharyngitis, rhinitis, follicular conjunctivitis, and regional lymphoid hyperplasia with tender preauricular adenopathy [3]. The identification of pathogenic agents contributes to the differential diagnosis of these three infectious diseases. Coxsackievirus A24 variant (CVA24v) and enterovirus D70 (EV-D70), belonging to the genus Enterovirus in the family Picornaviridae, are implicated as the major pathogens involved in AHC [4], [5]. Since the beginning of the 21st century, CVA24v has caused outbreaks of AHC in many countries, including China in Asia [6], Spain in Europe [7], Brazil in America [8] and Gambia in Africa [9]. EKC is associated with various human adenoviruses (HAdVs) infections [2]. HAdVs belong to the genus Mastadenovirus in the family Adenoviridae, which are double-strand DNA viruses and exhibit high species diversity and diversification of pathogenicity [10]. Based on genome-wide phylogenetic relationship, HAdVs are classified into seven groups, HAdV-(A–G) [10]. To date, a total of 116 HAdV genotypes have been identified in these seven species, with HAdV-D containing the most members (http://hadvwg.gmu.edu/). PCF principally attributes to HAdV-B infections, particularly type B3 [3]. Apart from conjunctivitis, HAdV infections are also related to respiratory tract disease, gastroenteritis, hemorrhagic cystitis, pneumonia, hepatitis and plastic bronchitis [11], [12], [13].

China experienced the two large outbreaks of CVA24v associated with AHC in 2007 and 2010 [6], [14]. However, no CVA24v was detected in the acute conjunctivitis surveillance system in past decade in Shenzhen until 2023 when the third nationwide outbreak of AHC occurred in mainland China [15]. In the same period, CVA24v outbreaks also occurred in neighboring countries, India and Vietnam [16], [17]. Information about prevalence and genotype distribution of HAdV-associated with acute conjunctivitis is lacking in recent years in China. Herein, we summarize the hospital-based surveillance for acute conjunctivitis associated with CVA24v, EV-D70 and HAdV infections in Shenzhen, China during 2018–2024, and investigate the molecular characteristics of CVA24v that emerged in 2023 and genotypic diversity of HAdV circulating during 2020–2024.