Based on: The persistence of COVID-19 vaccine artifacts in bodily fluids and tissues: a systematic review — Future Journal of Pharmaceutical Sciences, 2026. DOI 10.1186/s43094-026-00939-2
Early expectations about COVID-19 vaccines assumed that their key components — modified messenger RNA and the spike protein it encodes — would be cleared from the body quickly, consistent with the normal turnover of RNA. This systematic review, however, examines multiple studies that report detecting these vaccine-derived components in human tissues and bodily fluids for unexpectedly long periods after vaccination.
The authors systematically review the evidence for these enduring components — modified mRNA, spike protein, and lipid nanoparticles — long after administration. They catalogue the analytical techniques used to detect them, discuss the sensitivity and specificity of different assays, and summarise the specific tissues and fluids in which the components have been identified.
A major emphasis is methodology. Because detection depends heavily on the assay used, the review scrutinises factors that could influence results and their interpretation, separating signals that reflect genuine persistence from those that might be artifacts of the measurement technique.
The review then explores possible biological explanations for prolonged presence. These include altered RNA stability arising from the chemical modifications used in the vaccines, slow clearance of the lipid nanoparticles that carry the mRNA, and the formation of stable complexes or reservoirs that allow components to remain within tissues. The evidence for each hypothesis is weighed against the limitations of the available data.
Ultimately, the authors conclude that the reported persistence of COVID-19 vaccine components is a phenomenon that warrants deeper investigation. While methodological factors must be considered carefully, the assembled evidence suggests that certain vaccine derivatives may remain detectable for extended periods. Understanding the mechanisms behind this, the review argues, is important both for assessing vaccine safety and for the improved design of future mRNA-based therapeutics.