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Spike Protein and Post-Vaccination Syndrome

Last updated: October 26, 2026

A small set of studies has looked for spike protein in people who report long-lasting illness after COVID-19 vaccination. This page summarises what they measured, what they found and what they cannot yet show.

What is post-vaccination syndrome?

Post-Acute COVID-19 Vaccination Syndrome (PACVS) describes chronic symptoms that begin soon after COVID-19 vaccination and last for months. It is also called post-vaccination syndrome (PVS), PCVS or Post-Vac-Syndrom. Reported symptoms such as fatigue, exercise intolerance, brain fog and neuropathy overlap heavily with Long COVID. There is no agreed case definition yet, which makes studies hard to compare.

What spike protein studies have found

  • Yale LISTEN (Bhattacharjee et al., 2025, preprint)

    A cross-sectional study of 42 people with post-vaccination syndrome and 22 healthy controls. Participants with PVS had higher levels of circulating spike protein, along with differences in T-cell profiles and more frequent signs of Epstein-Barr virus reactivation. The authors describe these as features that “merit further investigation”.

  • Patterson et al. (2025)

    Reported S1 spike protein inside CD16+ monocytes up to 245 days after vaccination in 50 people with symptoms lasting over 30 days, compared with 26 asymptomatic controls. Several authors are employed by the company that developed the assay, and the authors note that causality is not established.

  • 2026 systematic review

    Gathers reports of vaccine-derived spike and mRNA in bodily fluids and tissues, including the outlier cases with prolonged detection.

For comparison, in healthy vaccine recipients spike is usually undetectable in blood within about two weeks (Ogata et al., 2022). See how long spike protein stays in the body.

What remains unproven

  • Whether spike detected in these groups causes their symptoms.
  • Whether the spike comes from vaccination or from an unrecognised infection; current tests cannot always tell them apart.
  • How common detectable spike is among everyone with PVS, since the studies so far are small and recruited symptomatic people.
  • Whether removing spike would help. No treatment has been shown to do so in a trial.
Proposed clearance approaches, graded by evidence →

Ongoing research

The PACVS Research Summit (June 2026) brought researchers together on draft diagnostic criteria and a core biomarker panel for PACVS, which would make future spike protein studies easier to compare.

References