AUTHOR=Goh Yun Shan , Rouers Angeline , Fong Siew-Wai , Zhuo Nicole Ziyi , Hor Pei Xiang , Loh Chiew Yee , Huang Yuling , Neo Vanessa Kexin , Kam Isaac Kai Jie , Wang Bei , Ngoh Eve Zi Xian , Salleh Siti Nazihah Mohd , Lee Raphael Tze Chuen , Pada Surinder , Sun Louisa Jin , Ong Desmond Luan Seng , Somani Jyoti , Lee Eng Sing , NCID Study Group , COVID-19 Study Group , Maurer-Stroh Sebastian , Wang Cheng-I , Leo Yee‐Sin , Ren Ee Chee , Lye David C. , Young Barnaby Edward , Ng Lisa F. P. , Renia Laurent , Yu Jocelyn Jin , Soh Zheng Kuang , Chin Yi Qing , Lim Jonathan Jordon , Ongko Juwinda , Libau Eshele Anak , Abdullah Mohammed Ridzwan Bin , Diong Shiau Hui , Teo Jefanie , Yeo He Ping , Chua Adeline C.Y. , Chang Zi Wei , Nguee Samantha Y. T. , Carissimo Guillaume , Tan Yong Jie , Wong Joel Xu En , Torres-Ruesta Anthony , Amrun Siti Naqiah , Yeo Nicholas Kim-Wah , Chen Wendy Yehui , Ong Alice Soh Meoy TITLE=Waning of specific antibodies against Delta and Omicron variants five months after a third dose of BNT162b2 SARS-CoV-2 vaccine in elderly individuals JOURNAL=Frontiers in Immunology VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.1031852 DOI=10.3389/fimmu.2022.1031852 ISSN=1664-3224 ABSTRACT=

The emergence of new SARS-CoV-2 variants, such as the more transmissible Delta and Omicron variants, has raised concerns on efficacy of the COVID-19 vaccines. Here, we examined the waning of antibody responses against different variants following primary and booster vaccination. We found that antibody responses against variants were low following primary vaccination. The antibody response against Omicron was almost non-existent. Efficient boosting of antibody response against all variants, including Omicron, was observed following a third dose. The antibody response against the variants tested was significantly higher at one month following booster vaccination, compared with two months following primary vaccination, for all individuals, including the low antibody responders identified at two months following primary vaccination. The antibody response, for all variants tested, was significantly higher at four months post booster than at five months post primary vaccination, and the proportion of low responders remained low (6-11%). However, there was significant waning of antibody response in more than 95% of individuals at four months, compared to one month following booster. We also observed a robust memory B cell response following booster, which remained higher at four months post booster than prior to booster. However, the memory B cell responses were on the decline for 50% of individuals at four months following booster. Similarly, while the T cell response is sustained, at cohort level, at four months post booster, a substantial proportion of individuals (18.8 – 53.8%) exhibited T cell response at four months post booster that has waned to levels below their corresponding levels before booster. The findings show an efficient induction of immune response against SARS-CoV-2 variants following booster vaccination. However, the induced immunity by the third BNT162b2 vaccine dose was transient. The findings suggest that elderly individuals may require a fourth dose to provide protection against SARS-CoV-2.