https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10459685/

This pooled analysis included the results of COVID-19 anti-S antibodies at 9 months after the first vaccine dose in 2941 HCWs from seven different European cohorts included in the ORCHESTRA project.

We observed that a higher serological response was associated with previous COVID-19 infection and the administration of the third vaccine dose. Additionally, older age and the time elapsed since the first dose were inversely associated with the antibody level. These results are consistent with previous studies conducted in the ORCHESTRA project, albeit these previous analyses included a large number of HCWs than the current study population [18]. Seven groups of chronic diseases were identified at baseline. Having two or more chronic diseases was associated with a diminished serological response. Moreover, hypertension was the only disease that demonstrated a lower serological response at 9 months post-vaccination.

The progressive decline of vaccine immunity is common and widely acknowledged. Among the factors that influence the immune response to vaccination, which varies significantly among individuals, are intrinsic host factors (such as age, sex, genetics, and comorbidities), perinatal factors (such as birth weight, feeding method, and maternal factors), and extrinsic factors (such as pre-existing immunity, microbiota, and antibiotics) [23,32] There is limited literature regarding the serological response to SARS-CoV-2 in individuals with multimorbidity. A preprint publication conducted in Bangladesh focused on individuals aged ≥ 18 years, with a cohort of 1005 participants, of which only 72 had multimorbidity [23]. The study investigated the impact of comorbidities on humoral antibody response against the specific receptor-binding domain (RBD) of SARS-CoV2. Diabetes mellitus and kidney disease had a significant negative impact on the decline of humoral SARS-CoV-2-specific IgG and total antibody (TAb) response. IgG and TAb declined more rapidly in diabetic and kidney disease patients compared to the other morbidity groups. Follow-up serological measurements demonstrated that antibody response declined within 4 months after receiving the second dose. Although this study was not peer-reviewed and is descriptive, it indicates the same trend of a decreased serological response in individuals with multimorbidity [23].

Several studies show that hypertension is associated with a lower antibody response following vaccination with SARS-CoV-2 [32,33] Individuals with hypertension may also be at higher risk for breakthrough infections following vaccination. Nevertheless, in these studies, only cross-sectional determinations have been made and the kinetics have not been measured to identify the moment in which the decrease in antibodies begins. Periodic monitoring of the antibody levels might be a good indicator to guide personalized needs for further booster shots to maintain adaptive immunity. Nonetheless, it is important that people obtain their COVID-19 vaccination, especially people with hypertension. However, more research is needed to fully understand the relationship between hypertension and the serological response to SARS-CoV-2 vaccination.