PT  - JOURNAL ARTICLE
AU  - Zeng, Qiang
AU  - Yang, Xue
AU  - Gao, Qi
AU  - Lin, Biao-yang
AU  - Li, Yong-zhe
AU  - Huang, Gang
AU  - Xu, Yang
TI  - Immunological findings in a group of individuals who were non-responders to standard two-dose SARS-CoV-2 vaccines
AID  - 10.1101/2022.05.05.490815
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.05.05.490815
4099  - http://biorxiv.org/content/early/2022/05/06/2022.05.05.490815.short
4100  - http://biorxiv.org/content/early/2022/05/06/2022.05.05.490815.full
AB  - Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was declared a pandemic. The virus has infected more than 505 million people and caused more than 6 million deaths. However, data on non-responders to SARS-CoV-2 vaccines in the general population are limited. The objective of the study is to comprehensively compare the immunological characteristics of non-responders to SARS-CoV-2 vaccines in the 18-59 years with that in the 60 years and older using internationally recognized cutoff values. Participants included 627 individuals who received physical examinations and volunteered to participate in COVID-19 vaccination from the general population. The main outcome was an effective seroconversion characterized by anti-SARS-CoV-2 spike IgG level of at least 4-fold increase from baseline. Profiling of naive immune cells was analyzed prior to vaccination to demonstrate baseline immunity. Outcomes of effective seroconversion in the 18-59 years with that in the 60 years and older were compared. The quantitative level of the anti-spike IgG was significantly lower in the 60 years and older and in men among the 18-59 years. There were 7.5% of non-responders among the 18-59 years and 11.7% of non-responders in the 60 years and older using the 4-fold increase parameter. The effective seroconversion rate was significantly related to the level of certain immune cells before vaccination, such as CD4 cells, CD8 cells and B cells and the age. An individual with a titer of anti-SARS-CoV-2 spike IgG that is below 50 BAU/mL might be considered a non-responder between 14-90 days after the last vaccine dose. Booster vaccination or additional protective measures should be recommended for non-responders as soon as possible to reduce disease severity and mortality.Competing Interest StatementThe authors have declared no competing interest.