The Impact of Vaccine Type and Booster Dose on the Magnitude and Breadth of Sars-Cov-2-Specific Mucosal Iga

Abstract

The level of mucosal IgA correlates with protection, but how vaccine types and booster doses affect mucosal IgA remain incompletely understood. Furthermore, there is a lack of data comparing the breadth of mucosal IgA and systemic IgG. In this cross-sectional study, we compared the levels of IgA and IgG in saliva and serum specimens of 108 individuals who received the BNT162b2 (Pfizer) or CoronaVac (SinoVac) vaccine. While BNT162b2 (vs CoronaVac) or booster doses (vs two doses) were associated with higher levels of serum IgG, these were not significantly associated with the levels of salivary IgA among individuals with or without prior infection. Among non-infected individuals, the levels of serum IgG, serum IgA and salivary IgG were significantly higher against the ancestral strain than the Omicron BA.2 sublineage, but there was no significant difference in the levels of salivary IgA between the different strains. Salivary IgA had the weakest correlation with serum IgG (r=0.337) when compared with salivary IgG (r=0.629) and serum IgA (r=0.597). Our findings suggest that intramuscular COVID-19 vaccines elicit a distinct mucosal IgA response that differs from the systemic IgG response. As mucosal IgA independently correlates with protection, vaccine trials should include mucosal IgA as an outcome measure.

Note:
Funding Information: This work was supported by Theme-Based Research Scheme (T11/709/21-N) of the Research Grants Council, HKSAR, the Emerging Collaborative Project of Guangzhou Laboratory [EKPG22-01], and donations of Richard Yu and Carol Yu, Shaw Foundation Hong Kong, Michael Seak-Kan Tong, May Tam Mak Mei Yin, Lee Wan Keung Charity Foundation Limited, Hong Kong Sanatorium & Hospital, Respiratory Viral Research Foundation Limited, Hui Ming, Hui Hoy and Chow Sin Lan Charity Fund Limited, Chan Yin Chuen Memorial Charitable Foundation, Marina Man-Wai Lee, the Hong Kong Hainan Commercial Association South China Microbiology Research Fund, the Jessie & George Ho Charitable Foundation, Kai Chong Tong, Tse Kam Ming Laurence, Foo Oi Foundation Limited, Betty Hing-Chu Lee, and Ping Cham So.

Declaration of Interests: IFHN and KKWT report collaboration with Sinovac, Sinopharm and Wantai BioPharm. IFHN and KKWT are involved in the study of an intranasal DelNS1-nCoV-RBD COVID-19 vaccine. IFNH received payment from M.S.D. for speaking at the COVID-19 Regional Expert Input Forum 2021; is on the advisory board of Pfizer on COVID-19 management in 2022; was on the advisory board of Gilead on evolving treatment landscape in COVID-19 in 2021 and also on the advisory board of AstraZeneca and Fosun on the prevention of COVID-19 infection in 2022. Other authors declare no competing interests.

Ethics Approval Statement: This study was approved by the Institutional Review Board of the University of Hong Kong/Hospital Authority of Hong Kong West Cluster (HKU/HA HKW IRB) (Reference number: UW 13-265 and UW 21-214). Written informed consent was obtained from all study participants

Keywords: COVID-19 vaccine, SARS-CoV-2, Omicron variant, mucosal immunity, saliva, IgA