Investigation on an outbreak of respiratory tract infection caused by human rhinovirus in a school in Huzhou City， Zhejiang Province

Objective To investigate the epidemiological characteristics of an outbreak of respiratory tract infection caused by human rhinovirus （HRV） in a school in Nanxun District of Huzhou City， and provide scientific evidence for prevention and control of outbreaks of upper respiratory tract infection caused by HRV in the future.

Methods The investigation was performed according to the Guidelines for Response to Outbreaks of Influenza-like Illness （2018 version）. It mainly referred to the records of nonattendance due to illness， morning and afternoon examination， and hospital treatment records， to search for cases. Then CDC staffs carried out epidemiological investigation on cases， interviewed the head teacher， and inspected the site. Throat swabs were collected for detection of SARS-CoV-2 and subsequently 14 common viruses that may cause upper respiratory tract infection.

Results A total of 68 cases with HRV infection were identified. The first case and last case occurred on May 20 and 30， respectively. After a 3-day longest incubation period， there was no emerging case， suggesting the end of the outbreak. The incidence was 25.00% （11/44） in Class 101， 30.23% （13/43） in Class 109， 25.58% （11/43） in Class 110， 35.26% （16/45） in Class 211， and 39.96% （17/46） in Class 307. There was no significant difference in the incidence among classes （χ²=1.67， P>0.05）. The patients aged from 7 to 9 years. The incidence was 27.19% （31 / 114） in male and 34.58% （37/107） in female， with no significant difference （χ²=1.41， P>0.05）. The symptoms were mild， with no hospitalization， severe illness or death. The patients had mainly cough （100.00%）， sore throat （61.76%）， and runny nose （47.06%）， whereas had little muscle soreness （4.41%）. Of the patients， 69.12% visited hospitals， 23.53% took medicine by themselves， while 7.35% did not seek any medical treatment or medicine. Throat swabs were collected from 22 cases， testing negative for SARS-CoV-2. Then 14 common respiratory viruses were examined， of which HRV was positive in 16 cases.

Conclusion Children with HRV infection have milder symptoms compared to influenza infection， which is difficult to be noticed by school teachers and parents. Students should maintain personal hygiene and develop health habits. Moreover， schools should strength relevant health education， implement morning and afternoon health inspection， and prevent students with illness to routinely go to schools.