evidence: Can "vaccine shedding" cause side effects in unvaccinated people? No. There have been rumors of "vaccine shedding" causing side effects to people who have not been vaccinated. The idea is that someone who has been vaccinated is shedding spike protein to those around them who have not been vaccinated. [...] Shedding can’t happen without a live vaccine. The mRNA vaccines – Pfizer and Moderna – are not live vaccines and do not replicate. The Johnson & Johnson and AstraZeneca vaccines are considered live vaccines because they both contain adenovirus. (Again, they do NOT contain the coronavirus.) But the adenovirus in both the Johnson & Johnson and AstraZeneca vaccines can’t replicate, so there’s no way they can shed. Learn more about how adenovirus vaccines work.