Variant-Specific IgA Protects Against Omicron Infection

• Published in: The Journal of infectious diseases Vol. 230; no. 2; pp. e287 - e291
• Main Authors: Goh, Yun Shan, Fong, Siew-Wai, Hor, Pei Xiang, Loh, Chiew Yee, Wang, Bei, Salleh, Siti Nazihah Mohd, Ngoh, Eve Zi Xian, Lee, Raphael Tze Chuen, Poh, Xuan Ying, Rao, Suma, Chia, Po Ying, Ong, Sean W X, Lee, Tau Hong, Lim, Clarissa, Teo, Jefanie, Pada, Surinder, Sun, Louisa Jin, Ong, Desmond Luan Seng, Somani, Jyoti, Lee, Eng Sing, Maurer-Stroh, Sebastian, Wang, Cheng-I, Leo, Yee-Sin, Lye, David C, Young, Barnaby Edward, Ng, Lisa F P, Renia, Laurent
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 16-08-2024
• Subjects: Adult; Antibodies, Viral - blood; Antibodies, Viral - immunology; Antibody response; Brief Report; Clinical trials; Coronaviruses; COVID-19 - immunology; COVID-19 - prevention & control; COVID-19 Vaccines - immunology; Female; Humans; Immunization, Secondary; Immunoglobulin A; Immunoglobulin A - immunology; Immunoglobulin G; Immunoglobulin G - blood; Immunoglobulin G - immunology; Male; Middle Aged; mRNA; Prospective Studies; SARS-CoV-2 - immunology; Severe acute respiratory syndrome coronavirus 2; Singapore - epidemiology; Vaccination; Vaccines; Singapore; COVID-19; SARS-CoV-2; IgA; antibodies; Omicron; S protein; mRNA vaccine
• ISSN: 0022-1899; 1537-6613; 1537-6613
• DOI: 10.1093/infdis/jiad525

Abstract
Background
The emergence of rapidly evolving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, coupled with waning vaccine-induced immunity, has contributed to the rise of vaccine breakthrough infections. It is crucial to understand how vaccine-induced protection is mediated.
Methods
We examined 2 prospective cohorts of mRNA vaccinated and boosted individuals during the Omicron wave of infection in Singapore.
Results
We found that individuals who remain uninfected over the follow-up period had a higher variant-specific IgA, but not IgG, antibody response at 1 month after booster vaccination, compared with individuals who became infected.
Conclusions
We conclude that IgA may have a potential contributory role in protection against Omicron infection.
Clinical Trials Registration
. NCT05142319.
Higher variant-specific IgA, but not IgG, antibody response at 1 month after booster vaccination was associated with infection risk, where individuals, who remained uninfected over the follow-up period of at least 8 months, had higher variant-specific IgA than individuals who became infected.