Can Vaccines Cause Long-Term Health Problems?
Vaccines are an important advancement in preventing disease. Vaccine products are constantly monitored and reviewed for safety.
How are vaccines monitored?
Because certain types of side effects and long-term outcomes may not be found in initial clinical studies in smaller groups of individuals, vaccines have ongoing monitoring of adverse effects. These effects are monitored in adults, pregnant women, and infants and children. The Agency for Healthcare Research and Quality (agency responsible for overseeing the quality of healthcare) recently reported that there is no new evidence of an increased risk for adverse effects from vaccine administration.
Can vaccines, particularly those containing aluminum or thimerosal, cause autism or other neurodevelopmental issues in children?
Decades of high-quality, large-scale studies have not shown a definite link between vaccines and autism. Evidence to date supports that autism is an inherited genetic disorder.
Aluminum is added to vaccine products to enhance the immune response. Studies show that children who receive aluminum-containing vaccines do not have aluminum in their blood or hair above the established minimum risk levels that would increase risk for neurodevelopmental disorders such as autism.
Thimerosal is used in multi-dose vials vaccine products as a preservative. Extensive research and expert review have found no harm or association between use of thimerosal-preserved vaccines and autism in children. In addition, very few available vaccine products contain thimerosal today and no vaccines recommended for children have contained thimerosal since 2001.
Can vaccines cause autoimmune conditions?
It has been suggested that there is a link between vaccination and autoimmune conditions (e.g., multiple sclerosis [MS], thyroid disease, inflammatory bowel disease, diabetes type 1); however, some of these theories are based on exposure to viruses, not vaccination. This association has been extensively researched in clinical studies in multiple countries and no association between autoimmune conditions and vaccines has been reported.
Patients receiving flu vaccines may have a very small increased risk of Guillain-Barré syndrome (GBS; a rare autoimmune disorder where the immune system attacks nerves causing numbness in the arms and legs that can progress to paralysis); however, the chance of getting GBS is greater after influenza infection than the flu vaccine itself.
Can your immune system be overloaded due to multiple vaccinations?
There has been concern that giving too many vaccines at once, particularly in infants and children, may weaken the immune system causing an increased risk for illness. Studies show that giving multiple vaccines at one time only uses a small fraction of the immune response. One estimate indicates that infants have the capability to respond to 10,000 vaccines at a given time. The immune system can handle multiple vaccinations in combination or when given at the same time.
Can vaccines impact fertility?
Specific studies have reported that vaccination, specifically with COVID-19 and human papillomavirus (HPV) vaccines, do not affect fertility in men or women of child-bearing age. However, one study that was published proposing a link was later retracted (removed from publication) due to serious flaws in the design and analysis. The study did not consider the use of contraception by those in the study, which is a factor that would significantly affect fertility.
Another important consideration of vaccination is that infection due to HPV or COVID-19 can affect fertility in men and infection in pregnant women can increase the risk of miscarriage or other complications during pregnancy.
Summary
Concerns about the long-term safety of vaccines have been well researched and documented globally. It is important for researchers and health organizations to continue to monitor the long-term safety of vaccines.