Introduction
Respiratory syncytial virus (RSV) is one of the most important pathogens leading to severe lower respiratory tract infection in children. It causes 2.7–3.8 million hospitalizations and 94,600–149,400 deaths in children under five years of age each year[1]. It can also result in severe respiratory infections in high-risk adults or elderly healthy persons. Therefore, RSV has been raising concern[2] and RSV surveillance is being conducted in many countries. The United States has included RSV in the National Respiratory and Enteric Virus Surveillance System since 1989[3, 4]. Japan has used the National Epidemiological Surveillance System for Infectious Diseases to monitor RSV since 2003[5]. The European Union has initiated RSV surveillance using the existing influenza surveillance network since 2003[6, 7]. The United States also launched the Global Disease Detection project in 2004, which monitored influenza virus and RSV in several countries world[8]. Likewise, the World Health Organization began monitoring RSV using the global influenza network in 2017[9]. However, so far, a nationwide RSV surveillance network has not been established in China.
China has a heavy burden of RSV infection. Several studies have reported that the RSV detection rate in pneumonia cases in Chinese children could reach 17%–33% during the RSV epidemic season[10, 11]. However, these studies rarely cover RSV infections in adults (particularly in elderly persons). Given that China is the most populous country globally and its aging population problem is becoming more serious, we can speculate that the proportion of Chinese elderly adults with RSV should not be small. Therefore, more attention should be paid to RSV infections among Chinese adults, especially Chinese elderly adults.
Up to now, there is no licensed RSV vaccine available. Palivizumab is the only prophylaxis biological product approved by the Food and Drug Administration in the USA for use in infants at high risk of severe RSV infection[12], but it is expensive and was not approved by the Chinese Food and Drug Administration. In addition, there is still no specific therapy drug for RSV, and only symptomatic and supportive treatments for RSV infection are available. Thus, it is urgent to establish an effective RSV surveillance system that covers all age groups (particularly the population with a high risk of severe respiratory infection) in China, which would contribute to a better understanding of the epidemiological and clinical characteristics of RSV infection in different ages groups, a better controlling the RSV epidemic and a better administration of severe RSV infection cases.
Our research team has established the Respiratory Pathogen Surveillance System (RPSS) in Beijing since 2014, which consists of 17 Centers for Disease Control and Prevention (CDCs) and 30 sentinel hospitals. Using this surveillance system, we have monitored the 11 most common respiratory pathogens, including RSV, influenza virus, and adenovirus. In this study, we systematically investigated the prevalence of RSV in Beijing for four consecutive years from March 2015 to February 2019, and compared the clinical characteristics of RSV infection among people of different age groups, with a focus on children under five years of age and elderly adult over 60 years of age.
Population and Methods1.1 Ethics statement
This study was approved by the Ethics Committees at Beijing Center for Disease Prevention and Control. Enrollees (or their guardians if appropriate) were told the nature, purpose, procedures, and potential health impact regarding this study, and written informed consent was obtained from each one. Patients were required to provide consent by themselves if their age and medical condition were appropriate.