tetano
Editor, Senior Moderator
- Samuel MS Cheng[SUP]1,2[/SUP] , Chris Ka Pun Mok[SUP]2,3,4[/SUP] , Karl CK Chan[SUP]1[/SUP] , Susanna S Ng[SUP]5[/SUP] , Bosco HS Lam[SUP]6[/SUP] , Leo LH Luk[SUP]1[/SUP] , Fanny W Ko[SUP]5[/SUP] , Chunke Chen[SUP]3,4[/SUP] , Karen Yiu[SUP]5[/SUP] , John KC Li[SUP]1[/SUP] , Ken KP Chan[SUP]5[/SUP] , Leo CH Tsang[SUP]1[/SUP] , Leo LM Poon[SUP]1,7[/SUP] , David SC Hui[SUP]5,8[/SUP]
, Malik Peiris[SUP]1,7[/SUP] 
Omicron subvariant BA.2 circulation is rapidly increasing globally.
Aim
We evaluated the neutralising antibody response from vaccination or prior SARS-CoV-2 infection against symptomatic infection by BA.2 or other variants.
Methods
Using 50% plaque reduction neutralisation tests (PRNT50), we assessed neutralising antibody titres to BA.2, wild type (WT) SARS-CoV-2 and other variants in Comirnaty or CoronaVac vaccinees, with or without prior WT-SARS-CoV-2 infection. Titres were also measured for non-vaccinees convalescing from a WT-SARS-CoV-2 infection. Neutralising antibodies in BA.2 and BA.1 breakthrough infections and in BA.2 infections affecting non-vaccinees were additionally studied.
Results
In vaccinees or prior WT-SARS-CoV-2-infected people, BA.2 and BA.1 PRNT50 titres were comparable but significantly (p < 10 [SUP]− 5[/SUP]) lower than WT. In each group of 20 vaccinees with (i) three-doses of Comirnaty, (ii) two CoronaVac followed by one Comirnaty dose, or (iii) one dose of either vaccine after a WT-SARS-CoV-2 infection, ≥ 19 individuals developed detectable (PRNT50 titre ≥ 10) antibodies to BA.2, while only 15 of 20 vaccinated with three doses of CoronaVac did. Comirnaty vaccination elicited higher titres to BA.2 than CoronaVac. In people convalescing from a WT-SARS-CoV-2 infection, a single vaccine dose induced higher BA.2 titres than three Comirnaty (p = 0.02) or CoronaVac (p = 0.00001) doses in infection-naïve individuals. BA.2 infections in previously uninfected and unvaccinated individuals elicited low (PRNT50 titre ≤ 80) responses with little cross-neutralisation of other variants. However, vaccinees with BA.1 or BA.2 breakthrough infections had broad cross-neutralising antibodies to WT viruses, and BA.1, BA.2, Beta and Delta variants.
Conclusions
Existing vaccines can be of help against the BA.2 subvariant.
https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2022.27.18.2200178#html_fulltext