Fears of “viral shedding” and other concerns after the COVID-19 vaccine have led some businesses to ban vaccinated customers from the premises, believing vaccination poses a health risk to others.
We’ve seen this in Australia, in the northern New South Wales town of Mullumbimby, and on the Gold Coast in Queensland. We’ve also seen this internationally.
In the United States, a teacher warned her students not to hug their vaccinated parents for the same reason.
People can shed (or release) viruses after a viral infection, such as SARS-CoV-2, which causes COVID-19.
If people are infected, they can shed viruses via their respiratory secretions when they cough and sneeze. During the pandemic, that’s why we socially distance, wear masks and stay at home if we’re sick. We can only infect someone if the virus is live.
Some vaccines for other diseases contain live viruses that have been weakened (or attenuated). Examples are vaccines against measles, rubella, mumps, and herpes zoster (shingles).
These train your body to mount an immune response with a version of the virus that isn’t so dangerous.
For example, with the very effective vaccine against herpes zoster (shingles), there is a minimal risk the weakened virus can cause infection. However, this happened in less than one percent out of more than 20,000 people vaccinated over ten years. The majority of people infected this way had a weakened immune system.
COVID vaccines don’t contain the live virus to shed
However, none of the COVID vaccines approved for use anywhere around the world so far use live viruses.
Instead, they use other technologies to train our bodies to recognize SARS-CoV-2 and to mount a protective immune response should we ever be exposed to it.
For instance, the AstraZeneca vaccine is a viral vector vaccine. This uses a modified chimpanzee virus to carry the genetic instructions to produce the SARS-CoV-2 spike protein into the body. Your body then uses these instructions to make the spike protein and to raise a protective immune response.
The Pfizer vaccine is an mRNA vaccine containing genetic material to code for the spike protein. Once inside your cells, your body uses those instructions to make spike protein, raising a protective immune response.
Even if you could shed spike protein after vaccination, that wouldn’t be enough to cause an infection. For that, you need the actual virus, which the vaccines don’t contain.
And the mRNA in the Pfizer and Moderna vaccines is short-lived and quickly degraded in our cells. Again, the mRNA wouldn’t be enough to cause an infection. It would need to be packaged inside a live virus, which our vaccines don’t contain.