A recent review published in the journal Vaccine has highlighted the potential risks associated with non-live vaccines. The review suggests that these vaccines, which include influenza, COVID-19, hepatitis B, and diphtheria-tetanus-pertussis (DTaP) vaccines, may increase a person's risks of all-cause mortality and the potential risk of infections from the diseases they are meant to protect against.
Non-live vaccines use inactivated viruses, fragments, or genes of the pathogen to trigger an immune response without pathogen replication. On the other hand, live vaccines contain weakened forms of the pathogen that can replicate in the body, mimicking the actual disease progression. Live vaccines have been found to have beneficial nonspecific effects, training the innate immune system and increasing immunity to unrelated infections. In contrast, non-live vaccines may promote “tolerance” that increases susceptibility to unrelated illnesses.
The study primarily relies on the work of Danish researchers Dr. Christine Stabell Benn and professor Peter Aaby. Their research suggests that non-live vaccines weaken the immune system's ability to fend off infections, while live vaccines enhance the effectiveness of the immune system in defending against infections.
The review also highlights the order in which vaccines are administered as a factor in their effects. Studies on measles vaccines have found that administering a live vaccine after a non-live one neutralizes negative nonspecific effects. However, if this order is reversed, there is a negative effect.
The DTaP vaccine is singled out as having the most evidence of adverse nonspecific effects. Girls who took the DTaP vaccine had a 50 percent higher risk of dying than boys who received it. Additionally, vaccinated girls' risk of dying was over 2.5 times higher compared to unvaccinated girls.
Non-live vaccines are increasingly replacing live vaccines, which could pose potential health risks to the general immunity of the population. However, non-live vaccines are believed to be safer for people with depleted immune systems, as live vaccines can cause mild disease in the body.
Dr. Benn's research has faced skepticism from health authorities, as it implies that some vaccines may sometimes be harmful. Immunologists generally agree that some vaccines cause nonspecific effects, but how these effects should be quantified remains controversial.
Despite the potential superiority of live vaccines, pharmaceutical companies may be reluctant to produce them due to the challenges involved in their production. Live vaccines are dependent on various factors like temperature and water used for culturing.
It is important to distinguish between nonspecific effects and adverse events when evaluating vaccine safety. Nonspecific effects are considered separate from adverse events, and while live vaccines tend to cause positive nonspecific effects, they can also potentially cause adverse events.
