Analysis on the relationship of hybrid immunity and reinfection based on a school outbreak of SARS-CoV-2 omicron XBB variants in Shenzhen 2023
Objective This study aimed to analyze the characteristics of a school outbreak SARS-CoV-2 Omicron XBB variants in Shenzhen,to evaluate the effectiveness of hybrid immunity resulting from the first wave of COVID-19 infection and vaccination against reinfection,and to provide response strategy for the next wave of the epidemic.Methods Field epidemiology method were used to investigate and control the COVID-19 outbreak in a school.Counting data was described by frequency and component ratio,the rates between groups were compared by using x2 or Fisher exact tests.The protective effect of hybrid immunity and COVID-19 reinfection was analyzed by using unconditional logistic regression analysis,the difference P＜0.05 was considered statistically significant.Results The XBB.1.9.1 strain identified by genetic sequencing.The outbreak lasted for 10 days,with a total of 28 cases reported among students in a class,the incidence rate was 46.67％.The infection rates for close contacts and general contacts were 72.22％and 35.71％,respectively,the difference was considered statistically significant(x2=5.36,P=0.021).Among cases,85.71％were reinfections and 14.29％were first infections.Symptoms of reinfection were mainly upper respiratory tract infections like sore throat(54.17％).Symptoms of systemic poisoning such as fever were mild in reinfection(12.50％),the symptom of first infection was mainly fever(83.33％).In terms of immunization status,90.00％of the whole basic immunization was fully vaccinated.Additionally,88.33％had a history of previous CO VID-19 infection.The infection rates in the hybrid immunity group and non-hybrid immunity group during this outbreak were 43.13％and 66.67％,respectively,the difference was no statistically significant(Fisher's exact test P＞0.05).After adjusting for contact intensity,the non-hybrid immunity group had a higher risk of infection compared to the hybrid immunity group(OR=5.333,95％CI:1.10-25.99),with an protective effectiveness rate of 35.29％against reinfection in the hybrid immunity group.Conclusions The symptoms of COVID-19 reinfection are milder than first infection.Hybrid immunity provided by a combination of infection and vaccination can provide effective protection against subsequent COVID-19 infection.Schools should maintain the sensitivity of respiratory symptom surveillance systems to early detect and report,thereby reducing the risk of outbreaks.COVID-19 booster shots are recommended for students with previous infections to improve their immunity against COVID-19.
万方数据
维普
