A Cost-Benefit Analysis of Vaccines

Worries about safe manufacture, the effects of additives, and the side effects of vaccines have been subjects of public concern in recent years, but the benefits far outweigh potential costs.

Vaccines have helped transform health and health care around the globe. It's hard to believe that diseases like polio, smallpox, diphtheria, and whooping cough were common ailments within the last century. Today, these diseases are virtually or totally eradicated. This change is largely due the development of vaccines, which give our bodies the tools to fight disease-causing viruses and bacteria more effectively than they can by themselves.

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The CDC has calculated that many millions of additional deaths would be expected each year if we were to stop vaccinating today. The GAVI alliance, a non-profit that works to bring vaccinations to people across the globe, estimates that even today, every 20 seconds one life is lost to vaccine-preventable diseases: this is the equivalent of 1.7 million preventable deaths worldwide each year. Other estimates suggest that this number is much higher, at three million.

Despite their well-documented benefits, vaccines are frequently the subjects of public concern. Worries about safe manufacture, the effects of additives, and vaccines' side effects are some of the concerns that have accompanied vaccines in recent years.

It is possible to weigh the costs or risks of vaccines against the benefits they make possible and come up with a cost-benefit ratio. Considering what vaccines are all about, including how and where they are made and which concerns are legitimate and which appear unfounded yields a cost-benefit calculation that isn't as tricky as you might believe.

WHAT IS A VACCINE?

Vaccines help the body fight disease by giving it a "preview" of a pathogen that it might someday have to fight in earnest. Vaccines contain a version of a microbe, often an inactive form of a virus or bacterium, which triggers the immune system to make antibodies. Live, "attenuated" organisms in vaccines like measles-mumps-rubella (MMR) are weakened forms of the microbe -- they trigger an immune reaction, but they are not as virulent as the real thing, so they are less able to cause infection. Still, the immune system treats the live viruses in vaccines as if they were "real," and quickly creates antibodies against them.

Other vaccines, like hepatitis A and influenza, use "killed" organisms, which are also effective in triggering the immune system to make antibodies, yet they pose even less risk of infection because they are less intact. The immune system clears the microbes, or pieces of microbes, from the body, but, as with a regular infection, the antibodies remain. In this way, if an actual microbe is encountered, the body will be well prepared to attack it -- because it already has antibodies against it -- before the microbe leads to a full-blown infection.

RISKS AND ADVERSE REACTIONS

It's natural to be nervous about things we put into our bodies and those of our children -- particularly those that are injected into us -- so some people are concerned about the safety of vaccines. From what we know, there are some concerns that are warranted and some that are not, based on the evidence.

Additives Appear Safe

There are a number of components to vaccines. Besides the pathogen in the vaccine, there are other ingredients, some of which have raised questions or concerns in the past. The main ingredients in vaccines include suspending fluid, preservatives, stabilizers, and adjuvants, which enhance the response of the immune system to the particular antigen in the vaccine.

Vaccines may also contain antibiotics to stop the growth of bacteria in the suspension; egg protein (in flu and yellow fever vaccine), which comes from the manufacturing process; formaldehyde, which is used to inactivate bacteria; monosodium glutamate (MSG) as stabilizer against light, heat, humidity, and acidity; and thimerosal, which is a preservative containing mercury.

People have worried about thimerosal being linked to developmental problems, though most childhood vaccines no longer contain it. It is removed toward the end of the manufacturing process, although tiny amounts may still remain in the final product. Flu vaccine is one type containing small amounts of mercury. The American Academy of Pediatrics suggests that the mercury in vaccines is so negligible that there is no possibility for it to effect early development. They also point out that since mercury has been removed from vaccines in recent years, autism rates have actually increased, suggesting that there is absolutely no link between mercury and autism, as some have been concerned about.

Another additive, formaldehyde, is found in such tiny amounts that there is virtually no risk of it posing harm to the vaccine recipient. Likewise, the antibiotics used in the production of vaccines show up in tiny or undetectable amounts in the final product, so the safety concern is almost nil. Aluminum salts or gels are common adjuvants: While aluminum can pose problems in high doses, the amount in vaccines is thought to be quite safe.

These additional ingredients in vaccines can sound a little mysterious, but the bottom line is that they are found in such tiny amounts -- or removed by the end of the manufacturing process -- that the risks are vastly overshadowed by the many benefits that come along with vaccination.

Reactions May Occur

A more realistic concern is that giving a vaccine may spark an immune reaction that is similar to -- although typically much milder than -- the disease the vaccine is designed to protect against. Symptoms can mirror those caused by the pathogen itself: in the case of the flu vaccine, for example, common side effects may include fever, aches, and cough. These effects are usually quite tolerable, and go away within a few days.

Some people cannot tolerate certain vaccines, like the influenza vaccine, because chicken eggs are used to grow the vaccine in the lab (yellow fever is another that uses eggs). The residual egg protein in the vaccine can pose a problem for people who are egg-allergic. The measles-mumps-rubella (MMR) vaccine typically contains a much smaller amount of egg protein, and does not usually cause a reaction in egg-sensitive people. Gelatin is another additive that can cause an allergic reaction, though it is also very rare.

Major Adverse Events Are Real but Rare

Beyond the considerations mentioned above, there are some adverse events that are clearly the result of vaccines, though they are extremely rare. Some people may experience a severe allergic reaction to the vaccine, which can be serious. Symptoms can include fever, swelling of the throat, difficulty breathing, dizziness, hives, fast heartbeat, and seizure.

The FDA and CDC closely monitor and catalog these adverse events, through the Vaccine Adverse Events Reporting System (VAERS), which is designed to detect new adverse events, track increases in events, identify risk factors, determine the safety of new vaccines, and identify lot numbers that are linked to more adverse events. VAERS has its limitations. It is difficult to determine whether the adverse events reported actually have to do with the vaccine or another, unidentified variable. Studies have found that the VAERS data contain "strong biases," and that the specific risk associated with vaccines is virtually impossible to calculate based on the data. Researchers have more recently turned to other means, like large-linked databases (LLDB), from which they can draw from patients' complete medical histories in addition to their vaccine history, which can provide a more complete picture.

Roughly 30,000 adverse events in the United States are reported to the organization each year, a miniscule number given the number of vaccines administered in year. Of these reported events, only 10 to 15 percent are determined to be serious, resulting in hospitalization, serious health problems, or death.

Looking at the total number of vaccines given over a ten-year period -- 1.9 billion -- there were 128,717 reports of adverse events in total, which includes both serious and non-serious events like side effects including fever, rash, and soreness at the injection site. This comes out to only about 0.006 percent of the people who are vaccinated experiencing an adverse effect -- a tiny number, indeed.

Despite the possible shortcomings of the standard VAERS method of reporting, it is probably safe to say that adverse events are extraordinarily rare, and that the risks of not vaccinating strongly outweigh the risks of getting vaccinated.

PARENTS WHO SKIP VACCINATIONS

Given the rarity of adverse events and the safety vaccines provide, why do some parents refuse them? One recent study found that 77 percent of parents had asked their child's pediatrician to alter the recommended vaccination schedule, with roughly 60 percent of pediatricians agreeing to the adjustments, usually a simple delay in giving one or more vaccines. When all was said and done, about one in 10 parents chose to alter the routine vaccination schedule for their children in some way.

This trend to alter the vaccination schedule is likely fueled by the persisting worry that vaccines are linked to conditions like autism and Guillain-Barre Syndrome (GBS), an autoimmune disease in which the immune system attacks part of the nerve cell, rather than by the fear of adverse events. Some parents may ask to separate vaccines that are typically given together, space them further apart, or skip shots completely. But as the evidence keeps showing, the likelihood of vaccinations being connected to serious disorders or disease is so small -- or, in the case of autism-vaccine connection, overturned completely by newer research -- that skipping doses or changing the schedule is likely unwarranted.

Likewise, where a connection between the flu vaccine and GBS was once raised, recent evidence suggests there is no such link, and the CDC suggests that the risk of flu and its complications is much greater than any GBS would possibly be.

For these reasons, parents are usually encouraged to follow the vaccination schedule as best as possible. The effects of voluntarily adjusting the recommended schedule have not been measured yet, but it will be interesting to watch in the coming years, as it surely will be.

Relying on Others Is Becoming Less Reliable

We do know that parents' decisions to skip vaccines have had some important impacts on community health. Parents who wish to skip their children's vaccines are essentially relying on the fact that other children in the community will be vaccinated. Since in some communities this assumption is becoming less and less true, communities can be more at risk of disease than ever. In California, a sizable percentage of parents of kindergartners have applied for vaccine exemptions based on personal belief. In 2010 an outbreak of whooping cough killed 10 babies and affected more than 9,100 people.

Outbreaks of measles have been popping up again in this country, which the CDC has found at least partially due to children not receiving the MMR vaccine because of parental concerns for its safety. (They offer a pamphlet for parents who are considering altering the schedule.)

Luckily, despite the fact that doctors are often willing to alter the vaccination schedule for parents who wish to do so, they were less willing to alter vaccines against diseases that are still very much a threat today: H influenzae type b vaccine (Hib), diphtheria-tetanus toxoids-acellular pertussis vaccine (DTaP), and pneumococcal conjugate, which protects against meningitis. It is important to talk to your child's doctor about the risks and benefits associated with skipping doses as opposed to sticking to the recommended schedule.

MANUFACTURING CONCERNS

Vaccine production has accelerated rapidly in recent history, with half of existing vaccines developed in the last 25 years. The biomedical processes of vaccine-making are complex and beyond the scope of this article, but know that the organisms in vaccines need to be grown in the lab over a several-month period. And given the need for vaccines in this country, and around the globe, the production system can be taxed, so supply becomes an issue. Complicating the picture is that because the profit margin for vaccines is not large, the number of vaccine manufacturers has actually declined quite considerably in the past few decades, leaving only a handful in the U.S. today.

Because of the significant need for vaccines across the globe, production practices are changing to meet the growing demand, particularly in the locations in which they are manufactured. Recently the World Health Organization (WHO) gave the OK to China to begin producing vaccines.

This development could help people across the world gain access to the life-saving vaccines that are clearly needed. But given China's history of product safety concerns, it could be a while before people are comfortable accepting the "Made in China" label for vaccines. Last year, Chinese-imported drums of honey were seized because they contained an antibiotic known to be toxic to humans. In 2008, tens of thousands were sickened from milk powder, and a year earlier tainted cough syrup was responsible for the deaths of 94 in Panama. Time will tell how China's entry into the vaccine market will affect public confidence in their production practices -- and how it will affect access to vaccines across the world, and here at home.

A DOSE OF REALITY

It is understandable that parents -- or anyone -- might be concerned about the risks posed by vaccines, but the bottom line is that for almost any individual their benefits clearly outweigh the risks. For a select group of people, vaccines may cause an allergic reaction, but these cases are rare, and can often be avoided if one is aware of existing allergies (egg or gelatin) that might trigger it. Extreme adverse events are even rarer. The individual additives in vaccines are present in such small doses that the likelihood that they would affect a body in any meaningful way is virtually nil.

It can be easy to forget about the serious consequences of the diseases that vaccines protect against if you haven't seen them firsthand. The diseases that are prevented by giving vaccines are not pretty and can be life threatening -- and the complications, like meningitis, for example, can be grave. Tiffany Thornton, a spokesperson for Voices of Meningitis, is a survivor of meningococcal disease. She has devoted her time to raising awareness of the disease because so many are unfamiliar with fact that it can cause long-term brain and organ damage, and that it can be life threatening.

We also tend to discount the severity of the diseases that we do not see because they have been close to eradicated by inoculation. The FDA reminds us that "[t]oday there are far fewer visible reminders of the suffering, injuries, and premature deaths caused by disease that can now be prevented with vaccines." Just ask someone who's seen diphtheria in action whether vaccination against it is a good idea. Luckily, there aren't many people who have seen a diphtheria infection these days, since it's been virtually wiped out by vaccination.

The vaccine issue essentially boils down to a numbers game. Pitting the risks of vaccines against the risks of disease is really at its center. The number of people who become sick -- and die -- each year from diseases that could have been prevented by vaccination far outstrips the number of people who are affected by the vaccine itself. It can be easy to lose sight of this fact since the exceptions -- the few children whose health has been damaged by a reaction to a vaccine -- are more visible than the millions of cases of disease that never occurred. But the numbers don't lie. The research does the math for us, and continues to arrive at the same answer: Virtually across the board, vaccines' benefits outweigh their risks, making them the best way to ensure a healthy future for children and adults.

Image: Sura Nualpradid/Shutterstock.

This article originally appeared on TheDoctorWillSeeYouNow.com, an Atlantic partner site.