The public perception of vaccines seems to be that being vaccinated is synonymous with having an acquired immunity. Medically this is highly inaccurate.
For those who are vaccinated there will always be a risk of vaccine failure:
- Primary – where the vaccines fail to take. That despite the vaccine being administered, the body doesn’t produce the desired immunological response.
- Secondary – where the vaccines wear off. Vaccine induced immunity is temporary typically lasting between 2 years to 10 years.
Thus, despite the aggressive childhood vaccination schedule, the commonplace over-generalised application of the principle of herd immunity to vaccine induced immunity is deeply flawed. Herd immunity was a principle derived from the observations of in those with the life-long immunity, induced by wild exposure, yet is frequently misapplied to a population with a temporarily induced immunity that wanes with time. Unfortunately, vaccine efficacy is also known to reduce as recipients age; some research also shows that the more repeated vaccination for the same illness the less effective it is. This is known to be a contributing factor toward the flu vaccinations consistently poor efficacy in older recipients as well as the resurgence of measles and mumps outbreaks in young adults, particularly in university communities, as well as the current US naval ship mumps outbreak.
In addition to these more accepted forms of vaccination failure, there is also a risk of self-culturing and developing illnesses as a result of vaccinations, otherwise known as negative efficacy. Live attenuated vaccinations, such as the rotavirus, MMR, chickenpox/shingles and most flu vaccines contain live strains; which increase the risk of the recipient developing the illnesses and/or being contagious for up to a month after receiving them. Which is why it is routine for neonatal, oncology, intensive care and immunology wards to have warnings for those who are recently vaccinated with live vaccines not to enter, as those who are recently vaccinated can put those with immature or impaired immune function at risk.
A prime example of negative efficacy is the 2017-2018 flu vaccine when given to children, despite it being most effective in the child population with one strain providing up to 90% protection, another strain in the vaccine had a negative efficacy of 75%, meaning 75% of the children who received the vaccine self cultured and developed the flu from that particular strain. It’s also estimated around 5% of those who receive the MMR will develop the measles as a result of the vaccine itself. These shedding periods typically peak within 1-2 weeks but can last for 4 weeks or longer in some individuals. One man was in the news for shedding the polio virus for over 30 years, due to an underlying immune deficit which had not been identified or taken into consideration before he received the live virus.
Primary vaccine failure to routine vaccines: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4962729/
Identification of Primary and Secondary Measles Vaccine Failures by Measurement of Immunoglobulin G Avidity in Measles Cases during the 1997 São Paulo Epidemic: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC321355/
Man sheds polio for 30 years: