Vax mRNA Stays in Blood for At Least 28 Days After Injection: Peer-Reviewed Danish Study

Scientists in Denmark have confirmed that the mRNA vaccine sequences of the Pfizer-BioNTech and Moderna COVID-19 vaccines can circulate in the blood up to 28 days after vaccination.

The findings were published in the Journal of Pathology, Microbiology and Immunology.

“[F]ull-length or traces of SARS-CoV-2 spike mRNA vaccine sequences were found in blood up to 28 days after COVID-19 vaccination,” the study authors write, before emphasizing they were the “first” to make the discovery.

“To our knowledge, our study is the first to detect Pfizer-BioNTech and Moderna COVID-19 mRNA vaccine sequences in blood after vaccination, and therefore provides new knowledge regarding the timeframe in which the mRNA can be detected,” they write.

The researchers found traces of SARS-CoV-2 spike mRNA vaccine sequences in the plasma of 10 out of 108 patients with chronic hepatitis C virus (HCV) infection who had received the mRNA vaccines.

The patients “had recently received SARS-CoV-2 mRNA vaccinations according to the Danish roll-out vaccination plan,” according to the peer-reviewed study.

mRNA vaccines are made of a modified version of the genetic instructions for a protein called spike, which is found on the surface of the SARS-CoV-2 virus that causes COVID-19. These genetic instructions are wrapped up in tiny packages called lipid nanoparticles, which deliver the instructions to cells in the body. Once the instructions are delivered, they are expected to break down and disappear within a few hours to a few days.

However, the study shows that the mRNA vaccine may remain in the body for longer than expected.

The study raises important questions about the design of lipid nanoparticles and the half-life of mRNA vaccines in humans and calls for further research to establish the half-life of mRNA vaccines in vaccine recipients.

“Detection of mRNA vaccine sequences in blood after vaccination adds important knowledge regarding this technology and should lead to further research into the design of lipid-nanoparticles and the half-life of these and mRNA vaccines in humans,” the authors state.


The U.S. Centers for Disease Control and Prevention (CDC) claims, apparently incorrectly, that the vaccine’s mRNA is broken down and removed from the body. On its website, the CDC says that after the spike protein piece is made within the body, “our cells break down the [vaccine] mRNA and remove it, leaving the body as waste.”

Nebraska Medicine also apparently incorrectly claims that the vaccine mRNA “is quickly degraded” in the body, even “within a few days.”

MedlinePlus, an online information service produced by the U.S. National Library of Medicine (NLM), also apparently incorrectly claims the mRNA is broken down “quickly” by the body.

A Reuters “fact check” also apparently incorrectly claims vaccine mRNA is broken down by the body “shortly” after it instructs cells to make spike protein.

Read the full study below: