How long can spike protein fragments persist in blood or tissues after mRNA vaccination?
Executive summary
Clinical studies and recent reports disagree with early assumptions that vaccine mRNA and spike proteins vanish in days: several investigations detect vaccine-derived mRNA up to ~30 days in tissues and spike protein fragments or soluble spike in some people for months to more than a year (examples include reports of ~187 days, ~11–17 months, and >700 days in select patients) [1] [2] [3]. Other expert summaries and hospital guidance continue to emphasize that mRNA is typically short‑lived (days) and that persistence does not prove active infection or harm [4] [5].
1. What early expectations said — and why they mattered
When mRNA vaccines were rolled out, manufacturers and public-health explanations said the injected mRNA would be locally translated for a short period (days) and then degraded, with produced spike antigens appearing briefly to train immunity; that framing shaped safety expectations worldwide [4] [1]. Those early expectations are the baseline against which newer detection studies are being compared [1].
2. Emerging measurements: tissue mRNA ~weeks, spike in blood months to years in subsets
Multiple publications report measurable vaccine-derived mRNA in lymph nodes and occasionally myocardium up to about 30 days after injection, and circulating or tissue spike protein detected for far longer in some people. A pharmacology review cites recombinant spike detectable “a little over half a year” (~187 days) in blood in selected studies [1]. Separate clinical and institutional reports document persistent spike protein detection in subsets of patients — including findings of spike present 11–17 months post