Childhood vaccine safety studies - ANTHONY R MAWSON

Professor Anthony R Mawson

"Although short-term immunologic and safety testing is performed on vaccines prior to their approval by the U.S. Food and Drug Administration, the long-term effects of individual vaccines and of the vaccination program itself remain unknown [8]. Vaccines are acknowledged to carry risks of severe acute and chronic adverse effects, such as neurological complications and even death [9], but such risks are considered so rare that the vaccination program is believed to be safe and effective for virtually all children [10]."

There are very few randomized trials on any existing vaccine recommended for children in terms of morbidity and mortality, in part because of ethical concerns involving withholding vaccines from children assigned to a control group. One exception, the high-titer measles vaccine, was withdrawn after several randomized trials in west Africa showed that it interacted with the diphtheria-tetanus-pertussis vaccine, resulting in a significant 33% increase in child mortality [11].

Evidence of safety from observational studies includes a limited number of vaccines, e.g., the measles, mumps and rubella vaccine, and hepatitis B vaccine, but none on the childhood vaccination program itself.

Knowledge is limited even for vaccines with a long record of safety and protection against contagious diseases [12].

The safe levels and long-term effects of vaccine ingredients such as adjuvants and preservatives are also unknown [13].

Other concerns include the safety and cost-effectiveness of newer vaccines against diseases that are potentially lethal for individuals but have a lesser impact on population health, such as the group B meningococcus vaccine [14].

A  complicating  factor  in  evaluating  the  vaccination  program  is that  vaccines  against  infectious  diseases  have  complex  nonspecific  effects  on  morbidity  and  mortality  that  extend  beyond  prevention  of  the  targeted  disease.

The  existence  of  such  effects  poses  a  challenge to  the  assumption  that  individual  vaccines  affect  the  immune  system  independently  of  each  other  and  have  no  physiological  effect  other  than  protection  against  the  targeted  pathogen  [21].

The  nonspecific  effects  of  some  vaccines  appear  to  be  beneficial,  while  in  others  they appear to increase morbidity and mortality [22,23]. For instance, both the  measles  and  Bacillus  Calmette–Guérin  vaccine  reportedly  reduce overall  morbidity  and  mortality  [24], whereas  the  diphtheria-tetanus-pertussis  [25]  and  hepatitis  B  vaccines  [26]  have  the  opposite  effect.

The mechanisms responsible for these nonspecific effects are unknown but  may  involve inter  alia:  interactions  between  vaccines  and  their  ingredients, e.g., whether the vaccines are live or inactivated; the most recently  administered  vaccine;  micronutrient  supplements  such  as vitamin A; the sequence in which vaccines are given; and their possible combined and cumulative effects [21].


Complete article here.


SOURCE:

Mawson AR (2017) Pilot comparative study on the health of vaccinated and unvaccinated 6- to 12-year-old U.S. children, J Transl Sci, 2017 doi: 10.15761/JTS.1000186, Volume 3(3): 2-12