Keep Factually independent
Whether you agree or disagree with our analysis, these conversations matter for democracy. We don't take money from political groups - even a $5 donation helps us keep it that way.
How long does spike protein persist in blood after COVID vaccination?
Executive summary
Published studies and news coverage show that in most people vaccine-derived spike protein is detectable for days to weeks after an mRNA COVID-19 shot, but several recent papers and small studies report detection in subsets of patients many months — even up to ~700 days — after vaccination, usually in people with persistent symptoms (PVS/long COVID) or specific complications such as myocarditis [1] [2] [3] [4]. Reporting and review articles disagree about how common long persistence is and what it means clinically; some studies have been retracted or remain preliminary [5] [2].
1. What early evidence said: transient, local expression measured in days–weeks
The initial, widely cited expectation from registrational and mechanistic work was that vaccine mRNA and the spike protein it encodes are mainly localized near the injection site and lymph nodes and are cleared within days to a few weeks; clinical summaries and health systems continue to describe spike/protein expression as short-lived, on the order of days to a few weeks [1] [6]. This remains the baseline message cited by public health sources [1].
2. Newer, peer‑reviewed signals: detection in blood or tissues months later
Multiple peer‑reviewed papers and preprints published 2023–2025 report detectable vaccine-derived spike or spike fragments in blood or tissues well beyond the initial expectation. Examples include mass-spectrometry detection in about half of samples up to 187 days, claims of spike fragments in tissues and circulation up to ~6 months, and reports of spike detected in cerebral arteries up to 17 months post‑vaccination in a small autopsy series [7] [6] [4]. Those studies document that persistence can occur — but they differ in methods, sample sizes and context.
3. Persistence focused in specific patient groups (PVS, myocarditis, long COVID)
Larger journalistic coverage and a prominent Yale study emphasize that persistent spike antigen has been observed mainly in people with post‑vaccination syndrome (PVS) or long COVID and in some cases of post‑vaccine myocarditis: Yale investigators reported some participants with PVS had detectable spike more than 700 days after vaccination [2] [8] [9]. Separate work on myocarditis patients showed free full‑length spike in blood and a slow decline over time in that cohort [3] [10]. These findings indicate persistence is not uniformly measured across the general vaccinated population in the presented sources [2] [3].
4. Magnitude, frequency and clinical implications remain disputed
Authors and reviewers disagree about how common long persistence is, why it happens, and whether it causes disease. Some reviews and articles propose mechanisms linking persistent spike to inflammation, microclots and multisystem symptoms and propose treatments, while others emphasize that finding antigen does not by itself prove harm and note many studies are small, specialized, or preliminary [11] [12]. One paper reporting spike in long‑COVID patient serum was later accompanied by a retraction note in the journal record, underscoring uncertainty and the need for cautious interpretation [5].
5. Methodological differences explain part of the disagreement
Studies use different assays (mass spectrometry, Simoa ultrasensitive antigen assays, in situ hybridization), sample types (plasma, tissue, arterial walls), and populations (autopsy cases, hospitalized myocarditis, self‑selected PVS cohorts). Those methodological and population differences make results hard to compare and explain why some series find persistence up to ~709 days while many others find clearance within weeks to months [3] [7] [4] [2].
6. How to interpret the headlines: cause vs. correlation
The presence of spike antigen months or years after vaccination in selected groups is an observed signal in recent work, but available sources do not establish that persistence is common across all vaccinated people or that it alone causes the reported syndromes in every case [2] [11]. Some authors explicitly link persistent spike to symptoms and propose mechanistic paths; others caution that persistence is seen only in subsets and that more study is required to determine causation [12] [11].
7. What researchers and clinicians are calling for next
Investigators quoted in reporting recommend larger, prospective studies with standardized assays, longitudinal sampling, and careful clinical correlation to determine how often spike persists, why it does so in some people, and whether removing or neutralizing persistent antigen alters outcomes [2] [9]. Given conflicting findings and at least one retraction, the literature requires replication and rigorous peer review before definitive clinical actions can be advised [5] [2].
Limitations: this summary relies only on the provided items and does not include other studies or statements that may exist outside this set; where the sources do not report prevalence across general vaccinated populations, that absence is noted (not found in current reporting).