In the U.S., vaccines have reduced or eliminated many infectious diseases that once routinely killed or harmed many infants, children, and adults. The viruses and bacteria that cause these diseases still exist and can be passed on to people who are not protected. Vaccine-preventable diseases have many social and economic costs and often result in doctor's visits, hospitalizations, and even premature deaths. Of course no vaccine is 100% effective and there are some risks of side effects.

Even one serious adverse event in a million doses of vaccine cannot be justified if there is no benefit from the vaccination. But looking at risk alone is not enough. Only by comparing the risk of the disease with the risk of the vaccine can we evaluate the benefit of a vaccination in regards to our children.

Let’s look at measles as an example. Before the measles immunization was available, nearly everyone in the U.S. got measles. An average of 450 measles-associated deaths were reported each year between 1953 and 1963. (CDC)

In all cases, about 20 percent of people with measles were hospitalized with about seventeen percent of these presenting with serious complications. Pneumonia is present in about six percent of cases and accounts for most of the measles deaths. Although less common, some people with measles develop encephalitis resulting in brain damage. Even now, as many as three out of every 1,000 people with measles will die in the Unites States, while in developing countries that rate is a staggering 1 in 100.

In the U.S., widespread use of measles vaccine has led to a greater than 99 percent reduction in measles as compared with the pre-vaccine era. According to the World Health Organization (WHO) there were nearly 900,000 measles-related deaths worldwide in 1999.  If vaccination programs were stopped, this highly infectious disease would account for 2.7 million deaths per year.

So what are the risks? A vaccine, like any medicine, is capable of causing serious problems, such as severe allergic reactions. The risk of MMR  (Measles, Mumps, and Rubella) vaccine causing serious harm, or death, is extremely small. Mild problems, including a fever or mild skin rash, occur in about 1 person out of 20. More serious reactions such as seizures caused by fever occur in 1 person out of 3,000 doses. Very serious allergic reactions possibly resulting in deafness, coma or brain damage happen in less than 1 person in 1,000,000 doses.

According to the National Institute of Child Health and Human Development (NICHD), some parents of children with autism believe that the Measles/Mumps/Rubella (MMR) vaccine caused their children’s autism. These parents report that their children were “normal” until they received the MMR vaccine and their beliefs and observations are reinforced by a small study of bowel disease and autism, published by Wakefield and his colleagues in 1998 (Wakefield et al 1998). The study’s authors suggested that there was a link between the MMR vaccine and autism however the study did not include any specific scientific testing to find out. The authors relied on the reports of parents and families of the 12 children with autism involved in the study to make their suggestion and this research has since been retracted by the original publisher; The Lancet. A number of other studies have also suggested a possible link between the MMR vaccine and autism (Singh et al 1998; Horvath et al 1999; O’Leary et al 2000; Wakefield et al 2000; Kawashima et al 2000), however to date, there is no definite, scientific proof that any vaccine or combination of vaccines can or does cause autism.

The MMR vaccine is only one of many vaccines that parents must evaluate on a case-by-case basis and clearly it is necessary to differentiate scientific evidence from anecdotal evidence and more importantly media hype.

There are four different types of vaccines currently used:

• Attenuated (weakened) live viruses are used in some vaccines such as in the Measles, Mumps, and Rubella (MMR) vaccine.
• Killed (inactivated) viruses or bacteria are used in some vaccines, such as in IPV.
• Toxoid vaccines contain a toxin produced by the bacterium. For example, the Diphtheria and Tetanus vaccines are toxoid vaccines.
• Biosynthetic vaccines (such as Hib) contain synthetic substances.

The American Academy of Pediatrics (AAP) recommends the following vaccinations and schedules.

• Birth - Hep B: Hepatitis B vaccine; may be given at any age for those not previously immunized.
• 1–4 months - Hep B: Second dose should be administered 1 to 2 months after the first dose.
• 2 Months - DTaP: Diphtheria, Tetanus, and Acellular pertussis vaccine, Hib: Haemophilus influenzae type b vaccine, IPV: Inactivated poliovirus vaccine, PCV: Pneumococcal conjugate vaccine, RV: Rotavirus vaccine, recommended for infants at 2, 4, and 6 months of age
• 4 Months - DTaP, Hib, IPV, PCV, RV
• 6 months - DTaP, Hib, IPV, PCV, RV
• 6–18 months - Hep B, IPV
• 12–15 months - Hib, MMR: Measles, Mumps, and Rubella (German measles) vaccine, PCV, Var: Varicella (Chickenpox) vaccine; may be given at any visit after first birthday. A second dose should be given between 4 and 6 years of age.
• 12–23 months - Hep A: Hepatitis A vaccine; recommended for kids 12–23 months old, given as two shots at least 6 months apart.
• 15–18 months - DTaP
• 4–6 years - DTaP, MMR, IPV, Var
• 11–12 years - HPV: Vaccine to prevent the human papillomavirus (HPV), Tdap: Tetanus, Diphtheria, and Pertussis booster, MCV: Meningitis vaccine; recommended for kids at age 11 years, and for kids age 15 who haven't had the vaccine or are entering high school
• College entrants - MCV4: Meningitis vaccine; recommended for previously unvaccinated college entrants who will live in dormitories.

All of these vaccines may not be essential and some are highly controversial. Some medical practitioners question the use of the Varicella vaccine as the chickenpox is not a serious childhood disease and it is unproven as to whether the vaccine’s protection extended into adulthood when the disease is much more harmful. Rotovirus is also a relatively benign disease. In the United States the Hep B vaccine could possibly be delayed until the child is more developed unless there is a specific risk of exposure. Since Hep B is a blood and sexually transmitted infection it would be appropriate if a child needs surgery, or requires a transfusion. Likely, it should be considered before the child enters puberty, as the risk of sexual assault of minors is high, and then teens are the highest risk group for STDs. The Hep A vaccine may also be optional unless a child is in a day care or other social situation on a regular basis or if the child is traveling outside of the U.S. 
 
In most states the law requires children to be immunized before they are admitted to public schools. However, exemption is provided on religious grounds and on medical grounds (if a physician certifies that the vaccination is detrimental to the child’s health). A third category of exemption, effective in most states, is provided for families for whom vaccination is contrary to their personal beliefs (Allen, 1988). Parents should be diligent and informed to make appropriate choices regarding these important matters. This requires careful examination of the potential risks of a vaccination contrasted with the very real and measurable risk of the disease.

Clearly, the safety of vaccinations is a critical issue and in which both parents and governmental agencies take very seriously. However, it would be hard not to conclude that vaccines are the most effective disease-preventing advancement in medical technology probably only topped by the engineering of a sanitary water supply. Information and education should be available to all parents regarding these important choices in their children’s health.