SARS-CoV-2原型株无症状感染对Omicron株BA.1、BA.2与BA.5的保护概率

Protection probability against SARS-CoV-2 Omicron variant BA.1,BA.2 and BA.5 in asymptomatic infection caused by prototype strain

目的评估SARS-CoV-2原型株无症状感染后对奥密克戎株(B.1.1.529,Omicron)BA.1、BA.2与BA.5感染、有症状感染和重症感染的保护概率。方法基于前期研究得到的无症状感染原型株者中和抗体动态曲线,利用logistic回归的预测模型估计无症状感染者在确诊后28 d、51 d和261 d对Omicron株BA.1、BA.2和BA.5感染所致的感染、有症状感染、重症三种结局的保护概率。结果SARS-CoV-2原型株无症状感染者在确诊后28 d,对Omicron株BA.1、BA.2和BA.5再感染的保护概率分别为30%(95%CI:16%~52%)、23%(95%CI:15%~36%)和8%(95%CI:4%~16%),到261 d分别降至9%(95%CI:3%~21%)、6%(95%CI:3%~12%)和2%(95%CI:1%~4%);确诊后28 d,对Omicron株BA.1、BA.2和BA.5有症状感染的保护概率分别为51%(95%CI:28%~80%)、42%(95%CI:26%~67%)和16%(95%CI:7%~40%),到261 d分别降至16%(95%CI:7%~35%)、12%(95%CI:7%~22%)和3%(95%CI:1%~8%);确诊后28 d对Omicron株BA.1、BA.2和BA.5感染所致的重症结局的保护概率分别为91%(95%CI:72%~98%)、88%(95%CI:70%~97%)和66%(95%CI:35%~90%),到261 d分别降至60%(95%CI:35%~86%)、51%(95%CI:32%~75%)和22%(95%CI:10%~50%)。结论SARS-CoV-2原型株无症状感染者体内的中和抗体对Omicron株BA.5的保护概率低于BA.1和BA.2,对重症结局的保护效果较好,有症状感染次之,对感染的保护效果较差。

Objective To estimate the protection probability against SARS-CoV-2 variant Omicron strains BA.1,BA.2 and BA.5 infection,symptomatic infection and severe disease outcomes in asymptomatic individuals infected with SARS-CoV-2 prototype strain previously.Methods Our previous study had shown that the dynamic change of neutralizing antibodies in asymptomatic individuals infected with the SARS-CoV-2 prototype strain.Based on our previous study,a peer-reviewed predictive model on the basis of logistic model was used to estimate the protection probability of asymptomatic individuals against Omicron strains BA.1,BA.2 and BA.5.We estimate the protection probability against infection,symptomatic infection and severe disease outcomes on 28,51 and 261 days after confirmation.Results The protection probability against reinfection of Omicron variant strains BA.1,BA.2,and BA.5 on 28 days after confirmation were 30%(95%CI:16%-52%),23%(95%CI:15%-36%)and 8%(95%CI:4%-16%)respectively,while decreased to 9%(95%CI:3%-21%),6%(95%CI:3%-12%)and 2%(95%CI:1%-4%)on 261 days after confirmation.The protection probability against symptomatic infection of Omicron strains BA.1,BA.2,and BA.5 were 51%(95%CI:28%-80%),42%(95%CI:26%-67%)and 16%(95%CI:7%-40%)respectively on 28 days after confirmation,while decreased to 16%(95%CI:7%-35%),12%(95%CI:7%-22%)and 3%(95%CI:1%-8%)on 261 days after confirmation.The protection probability against severe disease of Omicron strains BA.1,BA.2,and BA.5 were 91%(95%CI:72%-98%),88%(95%CI:70%-97%)and 66%(95%CI:35%-90%)respectively on 28 days after confirmation,while decreased to 60%(95%CI:35%-86%),51%(95%CI:32%-75%)and 22%(95%CI:10%-50%)on 261 days after confirmation.Conclusions Neutralizing antibodies induced in asymptomatic individuals infected with prototype strain could provide higher protection against Omicron strain BA.5 than Omicron strains BA.1 and BA.2.Among the three clinical outcomes,the protective probability against severe disease outcome was better,followed by symptomatic infection,and the protective probability against infection was poor.