Effect of completed COVID-19 vaccination on serum interferon λ3: a single-center retrospective study

The COVID-19 pandemic, which began in late 2019, has posed global health and economic challenges. Vaccination is crucial for reducing severe disease and hospitalization, although breakthrough infections occur. Understanding the immune response to vaccination, particularly the role of interferon lambda 3 (IFN-λ3), is essential for optimizing strategies.

This study aimed to investigate the relationship between COVID-19 vaccination status and serum IFN-λ3 levels in patients diagnosed with COVID-19.

This retrospective study analyzed 277 hospitalized COVID-19 patients admitted to Fukui General Hospital from July 2022 to March 2023. Patients were classified as insufficiently vaccinated (zero or one dose) or fully vaccinated (two or more doses). We collected demographic data, blood test results, and IFN-λ3 levels. Logistic and linear regression models were employed to analyze the impact of vaccination status on IFN-λ3 levels, with subgroup analyses assessing vaccine dose effects.

Of 277 identified patients, 140 were in the insufficient vaccination group and 137 in the completed vaccination group. Logistic regression revealed an inverse association between serum IFN-λ3 levels and completed vaccination status (odds ratio: 0.94, p = 0.019). Reduced likelihood of IFN-λ3 positivity was noted in the completed vaccination group (odds ratio: 0.27, p = 0.019). A marginal trend was observed for female sex (odds ratio: 0.61, p = 0.067). In linear regression, completed vaccination negatively correlated with serum IFN-λ3 levels (coefficient: -1.715, p = 0.017), while age positively correlated marginally (coefficient: 0.034, p = 0.081). Subgroup analyses showed no significant associations based on vaccine dose number.

Our findings suggest that completed COVID-19 vaccination may reduce IFN-λ3 levels, especially suppressing the likelihood of IFN-λ3 positivity (≥13.6 pg/mL), indicating a potential role of vaccines in modulating immune responses. A sex-specific effect was noted, with female sex displaying a trend toward lower IFN-λ3 levels and a significant negative association with IFN-λ3 positivity. Further research is needed to understand the relationship between IFN-λ3, vaccination status, and disease severity.