Recently, there has been a lot of misinformation circulating about “shedding” of the spike protein from those who are vaccinated with an mRNA-based COVID-19 vaccine (Pfizer-BioNTech, Moderna). False claims include that this “shedding” is causing the unvaccinated to become sick with COVID-like symptoms or experience changes in menstrual cycles. The Michigan Department of Health and Human Services made this the topic of last week's Education Corner series to address this important topic, as well as provide some talking points and resources on this issue.
Question: Do COVID-19 vaccines cause viral shedding?
NO! COVID-19 vaccines cannot give someone COVID-19 as the vaccines do NOT contain live virus. There isn’t a biological path for a vaccinated person to “shed” the COVID-19 virus spike protein to those around them.
First, the term “shed” was used in the early days of the pandemic to describe people transmitting or emitting coronavirus particles, when they were infected with SARS-CoV-2, the virus that causes COVID-19. The term “shed” was used as the scientists would measure “viral shedding” to try and pinpoint the time when sick individuals are the most infectious. The study of viral shedding is helpful to understand how infectious diseases spread, and it is necessary in determining appropriate actions needed for virus mitigation. Although the term “shedding” has been used to study the virus, this does not apply to COVID-19 vaccines.
The COVID-19 vaccines do not contain the live virus that causes COVID-19; therefore, they cannot make someone sick with COVID-19. During a COVID-19 infection, the entire virus is produced, but the COVID-19 vaccines only introduce nucleic acid related to one viral protein, the spike protein, so no other genes or proteins are available to produce viral particles. The COVID-19 vaccines give instructions to teach the cells in the body how to make that one viral protein, or even just a piece of protein. This triggers an immune response inside the body. After the protein piece is made, the cell breaks down the instructions and gets rid of them.
- The Pfizer-BioNTech and Moderna COVID-19 vaccines use a chemical messenger, or mRNA, to tell people’s cells to make proteins that mimic the outer surface of COVID-19 virus without replicating like the actual virus.
- The Janssen, Johnson & Johnson vaccine uses a weakened version of a harmless adenovirus to deliver instructions to cells to make coronavirus spike proteins that cannot replicate.
The body’s cells do not have the directions to make the whole COVID-19 virus. Therefore, it is impossible for the vaccines to result in the production of infectious virus particles.
In addition, when a person is infected with COVID-19, replication starts in the nasal cavity. If the immune system is unable to control replication, the virus may spread to other parts of the body and infect cells in other locations. This is why some people may be asymptomatic at the beginning, but then after about a week, they get more severely ill. The mRNA and adenovirus-vector vaccines are processed near the injection site, so the spike protein is never in an area of the body from which it could be shed, such as the nose.
For these reasons, viral shedding can occur when someone is infected with the virus that causes COVID-19 but getting a COVID-19 vaccine does not cause viral shedding.
If you have any questions regarding COVID-19 vaccination, you may always reach out to us at CHECCimms@michigan.gov.