Poor vaccine responsiveness towards third-dose mRNA vaccine of COVID-19 in Japanese older people

Augmented humoral response to third and fourth dose of SARS-CoV-2 mRNA vaccines in lung transplant recipients

BACKGROUND

Since lung transplant recipients (LTRs) exhibit low immunogenicity after two doses of SARS-CoV-2 mRNA vaccines, optimal vaccine strategies for SARS-CoV-2 are required in LTRs. This study aimed to investigate the efficacy and safety of the third and fourth doses of the SARS-CoV-2 mRNA vaccines in LTRs.

METHODS

We conducted a single-center study of 73 LTRs and 23 healthy controls (HCs). Participants received two-to-four doses of SARS-CoV-2 mRNA vaccines. The LTRs were divided into three groups based on the number of vaccine dose. IgG titers against SARS-CoV-2 spike protein were measured, and adverse events were assessed. Factors associated with humoral response were analyzed using univariate and multivariate analyses.

RESULTS

The Dose 4 group (n = 27) had a higher humoral response rate (P = 0.018) and higher levels of anti-SARS-CoV-2 IgG antibody (P = 0.04) than the Dose 2 group (n = 14). The Dose 3 group (n = 32) had lower humoral response rates (P = 0.005) and levels of anti-SARS-CoV-2 IgG antibody (P = 0.0005) than the HCs (n = 23) even after the same dose. Systemic adverse events were milder in the LTRs than in the HCs (P < 0.05). Increased number of vaccine dose was identified as a predictor of positive humoral response (P = 0.021).

CONCLUSION

Booster doses of SARS-CoV-2 mRNA vaccines may enhance humoral response with mild adverse events in LTRs. Repeated vaccination might be warranted for LTRs to prevent SARS-CoV-2 infection.

Anti-SARS-CoV-2 IgG antibody after the second and third mRNA vaccinations in staff and residents in a nursing home with a previous COVID-19 outbreak in Niigata, Japan

This study measured IgG antibody titers against spike (S) and nucleocapsid (N) proteins of SARS-CoV-2 before vaccination and after the second and third doses of an mRNA vaccine in staff and residents of a nursing home in Niigata, Japan. The study included 52 staff members, of whom six (11.5%) were previously infected with SARS-CoV-2, and 32 older residents, of whom 22 (68.8%) were previously infected. All participants received the first two doses in April-July 2021 and a third dose in January-March 2022. In staff, the median anti-S antibody titers (interquartile range) in previously infected and SARS-CoV-2-naïve individuals before vaccination were 960 (592-1,926) and 0.5 (0.0-2.1) arbitrary units (AU)/mL. Anti-S antibody titers 5 months after the second and third doses in previously infected staff were 7,391 (5,230-7,747) and 10,195 (5,582-13,886) AU. In residents, the median anti-S antibody titers in previously infected and naïve individuals before vaccination were 734 (425-1,934) and 1.1 (0.0-3.1) AU/mL. Anti-S antibody titers at 5 months after the second and third doses in previously infected residents were 15,872 (9,683-21,557) and 13,813 (6,689-20,839) AU/mL; however, there were no significant differences in titers between the second and third doses in previously infected residents. Anti-N antibody titers were higher in previously infected than naïve individuals, and titers decreased chronologically.

Examining the association between vaccine reactogenicity and antibody titer dynamics after the third dose of BNT162b2 vaccine using a mixed-effects model

Background

To mitigate the COVID-19 pandemic, many countries have recommended the use of booster vaccinations. The relationship between the degree of adverse vaccine reactions and elevated antibody titers is of interest; however, no studies have investigated the temporal changes in antibody titers based on repeated measurements after a third dose of the BNT162b2 vaccine.

Methods

This prospective longitudinal cohort study was conducted with 62 healthcare workers who received a third dose of the BNT162b2 at Okayama University Hospital, Japan. Venous blood draw and fingertip whole blood test sample collection were conducted at the early (3–13 days) and 1-month time points; only FWT sample collection was conducted at the 2-month time point. Information on adverse reactions within 1 week after vaccination was also obtained. The association between fever of 37.5 °C or higher and antibody titers after the third dose of BNT162b2 was examined using a mixed-effects model and Poisson regression with robust variance.

Results

A trend toward higher antibody titers in the early period after vaccination was observed in the febrile individuals, but the differences were not significant at 1 and 2 months post-vaccination (the partial regression coefficient for fever was 8094.3 [-1910.2, 18,098.8] at 1 month after vaccination, and 1764.1 [-4133.9, 7662.1] at 2 months after vaccination in the adjusted models).

Conclusion

The findings suggest that the presence of fever after the third vaccine does not predict a sustained elevation in serum antibody titers.