Recently, The Lancet published a study on the efectiveness of COVID-19 vaccines and the waning of immunity with time.
The study showed that immune function among vaccinated individuals 8 months after the administration of two doses of COVID-19 vaccine was lower than that among the unvaccinated individuals. According to European Medicines Agency recommendations, frequent COVID-19 booster shots could adversely affect the immune response and may not be feasible.
The decrease in immunity can be caused by several factors such as N1-methylpseudouridine, the spike protein, lipid nanoparticles, antibody-dependent enhancement, and the original antigenic stimulus. These clinical alterations may explain the association reported between COVID-19 vaccination and shingles.
As a safety measure, further booster vaccinations should be discontinued. In addition, the date of vaccination should be recorded in the medical record of patients.
Several practical measures to prevent a decrease in immunity have been reported. These include limiting the use of non-steroidal anti-infammatory drugs, including acetaminophen to maintain deep body temperature, appropriate use of antibiotics, smoking cessation, stress control, and limiting the use of lipid emulsions, including propofol, which may cause perioperative immunosuppression.
In conclusion, COVID-19 vaccination is a major risk factor for infections in critically ill patients.
The decrease in immunity is caused by several factors. First, N1-methylpseudouridine is used as a substitute for uracil in the genetic code. The modifed protein may induce the activation of regulatory T cells, resulting in decreased cellular immunity . Thereby, the spike proteins do not immediately decay following the administration of mRNA vaccines. The spike proteins present on exosomes circulate throughout the body for more than 4 months .
In addition, in vivo studies have shown that lipid nanoparticles (LNPs) accumulate in the liver, spleen, adrenal glands, and ovaries , and that LNP-encapsulated mRNA is highly infammatory . Newly generated antibodies of the spike protein damage the cells and tissues that are primed to produce spike proteins , and vascular endothelial cells are damaged by spike proteins in the bloodstream ; this may damage the immune system organs such as the adrenal gland.
Additionally, antibody-dependent enhancement may occur, wherein infection-enhancing antibodies attenuate the effect of neutralizing antibodies in preventing infection . The original antigenic sin , that is, the residual immune memory of the Wuhan-type vaccine may prevent the vaccine from being sufciently efective against variant strains. These mechanisms may also be involved in the exacerbation of COVID-19.