Large-Scale Real-World Study Finds No Increased Autoimmune Disease Risk Following Cecolin Vaccination

On August 10, 2026, Vaccines published a large-scale real-world study evaluating the risk of autoimmune diseases (ADs) following Cecolin vaccination.

Based on real-world data from more than 940,000 females aged 9–45 years, the study found no evidence of an increased risk of autoimmune diseases following Cecolin vaccination, adding to the post-marketing safety evidence for the vaccine.

A Large-Scale Real-World Population Study

The study was conducted by Xiamen Innovax Biotech Co., Ltd. (IX), in collaboration with the Xiamen Health and Medical Big Data Center, Tsinghua University, and other research partners.

Using electronic health data from the Xiamen Health and Medical Big Data Center, which covers more than 95% of local residents, the study included 944,382 females and accumulated 2,871,317 person-years of follow-up.

Among the study population, 92,026 females had received at least one dose of Cecolin. Vaccinated participants were matched with unvaccinated participants at a 1:4 ratio by age and calendar year. A rigorous case-validation process was applied to assess the occurrence of autoimmune diseases within 12 months following vaccination.

Six autoimmune diseases were included in the final analysis: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS), idiopathic thrombocytopenic purpura (ITP), and optic neuritis (ON).

No Increased Risk of Autoimmune Diseases Observed
The overall incidence of autoimmune diseases during the study period was 70.63 per 100,000 person-years.

Following matching by age and calendar year, no increased risk of autoimmune diseases was observed among Cecolin recipients compared with contemporaneously matched unvaccinated participants (IRR=0.23; 95% CI: 0.08–0.65; P=0.006). Consistent findings were also observed in analyses using historically matched unvaccinated participants.

The findings are broadly consistent with previous international studies and further contribute to the growing body of real-world evidence assessing autoimmune disease risk following HPV vaccination.

Expanding Post-Marketing Safety Evidence for HPV Vaccination

Autoimmune diseases are relatively uncommon, and their potential association with vaccination is best evaluated through large population-based studies and continued post-marketing surveillance. Real-world evidence therefore plays an important role in assessing vaccine safety throughout the product lifecycle.

By linking immunization records with electronic health data from a large regional healthcare database, the study provides additional epidemiological evidence on autoimmune disease risk following HPV vaccination among females in China.

The study also highlights the value of real-world data in active vaccine safety surveillance and provides scientific evidence to support the continued evaluation of HPV vaccine safety in post-marketing settings.

Interpreting the Findings

The study observed a statistically lower incidence of autoimmune diseases among vaccinated participants compared with unvaccinated participants. However, the authors cautioned that this finding should not be interpreted as evidence of a protective effect of HPV vaccination against autoimmune diseases.

Differences in health-related behaviors, healthcare utilization, and other residual confounding factors may have contributed to the observed association. The primary conclusion of the study is that no increased risk of autoimmune diseases was observed following Cecolin vaccination in this large-scale real-world population.

Reference
Zeng X, Yu X, Zhang Q, et al. Post-Marketing Safety Surveillance of Autoimmune Diseases Following Bivalent Human Papillomavirus Vaccination in China. Vaccines. 2026;14(8):687. Published August 10, 2026. doi:10.3390/vaccines14080687

Full Article:
https://doi.org/10.3390/vaccines14080687

This article is based on publicly available scientific literature and is intended for scientific and academic information exchange only. The findings should be interpreted in the context of the study design and its limitations. The content does not constitute additional claims or commitments regarding product efficacy or safety and is not a substitute for the professional judgment of healthcare professionals.