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From the eradication of smallpox to the imminent development of a cure for AIDS, immunization is a lifesaving innovation that has proven to be the most transformative public health achievement of the 20th century.
By Trudie Mitschang
If an ounce of prevention is worth a pound of cure, then vaccines are truly one of the most transformative public health achievements to come from the 20th century. Since their introduction, vaccines have eradicated smallpox, eliminated wild poliovirus in the United States, and significantly reduced the number of cases of measles and other diseases. Unfortunately, the successful track record of immunizations in the U.S. and other developed countries has led to an unwelcome side effect: Many people no longer understand the value of vaccines because they have never lived in a time when common childhood diseases were almost always deadly. While some may still view vaccines in a favorable light, increasingly vocal opponents regard them with suspicion and even contempt. Within the medical community, the need to educate and advocate on behalf of vaccine awareness, safety and efficacy has never been more urgent.
In a statement made during an April 2009 interview, Dr. David Tayloe, pediatrician and then-president of the American Academy of Pediatrics, stated: “Our citizens need to understand that the vaccine program has been extremely successful. It’s the most effective public health program in the history of man, and we cannot let down our guard just because we’ve done such a good job. We must continue to protect our children and protect our population.”1
Vaccines are a relatively recent development in medical history. It was just more than 200 years ago when English scientist Edward Jenner observed that milkmaids who had been exposed to cowpox seemed immune to contracting the dreaded smallpox infection. In 1796, Jenner tested his hypothesis by inoculating a boy named James Phipps with material from cowpox blisters. He later repeated the experiment on the boy, but this time added a small amount of smallpox, hoping the procedure would immunize James against infection. The experiment was a success, and Jenner’s discovery ushered in the dawn of the immunization age.2
It would be nearly a century later before the next scientific breakthrough in immunization occurred. In 1885, Dr. Louis Pasteur proved that infecting humans with weakened disease strains could prevent infection. Using an early form of a rabies vaccine, Pasteur successfully immunized a boy named Joseph Meister, who had been bitten by a rabid dog.3
By the mid-20th century, steady progress in immunization research had been made. Jonas Salk, MD, and Albert Sabin, MD, developed the inactivated polio vaccine and live polio vaccine, respectively. Their medical discoveries went on to save countless children worldwide from a disease that frequently left its victims wheelchair-bound or dependent on crutches for the rest of their lives. At the height of the polio epidemic in 1952, nearly 60,000 cases with more than 3,000 deaths were reported in the U.S. alone. However, with widespread vaccination, polio occurring through natural infection was eliminated from the U.S. by 1979, and eliminated from the Western Hemisphere by 1991.4
A half century ago, parents would have expressed disbelief that future generations of families would be able to protect their children from serious childhood infectious diseases. For many of us today, it is difficult to imagine a time when diseases like diphtheria claimed more than 10,000 lives annually in the U.S. Measles, another common disease, infected nearly half a million children in the U.S. each year, often leading to complications such as pneumonia and encephalitis. But, thanks to the advent of immunizations, many of these statistics have taken a positive turn.
Smallpox was declared eradicated from the world in 1977. As stated previously, polio was officially eliminated from the Western Hemisphere in 1991. The numbers for diphtheria are equally impressive: There were 12,230 deaths from diphtheria in the U.S. in 1921 (prior to the availability of a vaccine), but by 1998, just one case of diphtheria was documented. For the most part, the list of serious diseases that have been eradicated, or whose numbers have been dramatically reduced by immunizations, has grown steadily to include mumps, measles, rubella and tetanus.5 Documenting such data is important, because in the wake of increasing vaccine complacency, many of these once-eradicated diseases have begun making a comeback.6
According to the World Health Organization (WHO), at least two million people from all age groups die every year from diseases preventable by recommended vaccines. In fact, statistics show that more Americans die each year from vaccine-preventable diseases than from car accidents, breast cancer or AIDS. Influenza, commonly referred to as the flu, is at the root of an estimated 400,000 deaths worldwide each year and, surprisingly, it claims more lives than all other vaccine-preventable diseases combined. Another 2.1 million people die each year from diseases for which vaccines have yet to be developed.
In undeveloped countries, the statistics are even grimmer. The burden of vaccine-preventable death and disease is daunting; despite significant progress worldwide, two to three million children under age 5 die each year from diseases that could be prevented through immunization.7
One of the reasons communicable diseases seem to be rapidly reappearing is due to the global nature of the world in which we live. In many cases, coming into contact with unwanted illness and disease is a mere plane trip away. The California measles outbreak of 2008, for example, began when an unvaccinated child was exposed to measles during a trip to Sweden. He returned and quickly infected friends and classmates. Just how easily these types of infections can spread is documented by other recent outbreaks and epidemics:8
The American Academy of Pediatrics stated the following in its handout Vaccine Safety: The Facts: “Vaccines are necessary.… In many parts of the world many vaccine-preventable diseases are still common. Since diseases may be brought into the United States by Americans who travel abroad or from people visiting areas with current disease outbreaks, it’s important that your children are vaccinated.”9
Vaccine development has come a long way since Edward Jenner experimentally injected the pus from a cowpox blister into a young patient, leading to the creation of the smallpox vaccine. That first smallpox vaccine consisted of a live attenuated virus that had been weakened enough to provoke an immune response without causing a full-blown infection. Many of today’s vaccines, including measles and some influenza vaccines, also use live attenuated viruses, while others use killed forms of viruses, particles of bacteria and inactivated toxins. Currently, scientists are experimenting with new techniques in vaccine development, including the use of live recombinant vaccines and DNA vaccines.10
Live recombinant vaccines use attenuated viruses (or bacterial strains) as vectors: A virus or bacterium from one disease essentially acts as a delivery device for an immunogenic protein from another infectious agent. In some cases, this approach is used to enhance the immune response; in others, it is used when giving the actual agent as a vaccine would cause disease. For example, HIV cannot be attenuated enough to be given as a vaccine in humans; it could cause AIDS.
DNA vaccines consist of DNA coding for a particular antigen, which is directly injected into the muscle. The DNA itself inserts into the individual’s cells, which then produce the antigen from the infectious agent. Since this antigen is foreign, it generates an immune response. This type of vaccine has the benefit of being relatively easy to produce, since DNA is very stable and easy to manufacture. However, this technique is still experimental because no DNA-based vaccines have been shown to elicit the substantial immune response required to prevent infection. Researchers are hopeful that DNA vaccines may be able to generate immunity against parasitic diseases such as malaria (currently, there is no human vaccine that is effective against parasites).
The way vaccines are administered also is evolving. When most people think of vaccination, they think of a physician administering a shot. But future delivery methods will expand on that model to offer options with the potential to serve larger segments of the population. One new method showing promise is the use of inhaled vaccines. Influenza nasal sprays already are being used for seasonal flu, and other options on the horizon may include vaccine patches containing a matrix of tiny needles that deliver a vaccine without the need for a syringe. This method of delivery could be particularly useful in remote areas, as its application would not require administration by a trained physician or nurse.
An analysis of shipping and storage methods also is necessary in the quest to improve global vaccination rates. One of the challenges the industry now faces is known as the “cold chain” problem. Because many vaccines require cool storage temperatures in order to remain viable, their use in areas of the world where temperature-controlled storage is nonexistent is severely limited. Ironically, these tend to be the very parts of the world where vaccination is vitally needed for disease control. That’s why the race is on to develop vaccine materials that can be transported in a wide range of conditions without losing their efficacy.
Breakthroughs in the development of new vaccines have been making headlines lately, but significant improvements to existing vaccines also may be on the horizon. In a news release earlier this year, scientists at Oxford University announced they had successfully tested a universal flu vaccine that could work against all known strains of the illness, taking a significant step in the fight against a disease that affects billions of people annually.11
According to the study, the treatment targets a different part of the flu virus than traditional vaccines, meaning it does not need expensive reformulation every year to match the most prevalent virus strains that are circulating. Researchers say that if used widely, a universal flu vaccine could prevent pandemics such as the swine flu outbreaks of recent years, and end the need for a seasonal flu vaccine.
In response to the study’s findings, Mark Fielder, a medical microbiologist at Kingston University, said: “This study represents some potentially very exciting findings with positive implications not only for influenza but possibly for infectious disease in a wider context. The findings are extremely encouraging in terms of the apparent efficacy of the virus and that it appears to be a safe formulation. However, I think that a larger trial will be able to confirm these findings and let this technology be taken forward.”12
1. American Academy of Pediatrics. Sound Advice interview transcription. Accessed at www.aap.org/immunization/multimedia/soundadvice.html.
2. Riedel, S. Edward Jenner and the History of Smallpox and Vaccination. Department of Pathology, Baylor University Medical Center. Accessed at www.ncbi.nlm.nih.gov/pmc/articles/PMC1200696.
3. Encyclopedia of World Biography. Louis Pasteur Biography. Accessed at www.notablebiographies.com/Ni-Pe/Pasteur-Louis.html.
4. Kids Health/Infections: Polio. KidsHealth. Accessed at kidshealth.org/parent/infections/bacterial_viral/polio.html.
5. Trust for America’s Health. Closing the Vaccination Gap: A Shot in the Arm for Childhood Immunization Programs, August 2004. Accessed at www.ecbt.org/media/pdf/TFAH_ImmunizationRpt.pdf.
6. Healthy Children. History of Immunizations. Accessed at www.healthychildren.org/English/safety-prevention/immunizations/pages/History-of-Immunizations.aspx.
7. World Health Organization. Vaccine-Preventable Diseases. Accessed at www.who.int/immunization_monitoring/diseases/en/.
8. Iannelli, V. Vaccine Preventable Illnesses. About.com, Dec. 13, 2009. Accessed at pediatrics.about.com/od/immunizations/a/0408_im_illness.htm.
9. American Academy of Pediatrics. Vaccine Safety: The Facts. Accessed at www.aap.org/immunization/families/vaccinesafety_parenthandout.pdf
10. The History of Vaccines. The Future of Immunization. Accessed at www.historyofvaccines.org/content/articles/future-immunization
11. Oxford Biomedical Research Centre. Universal Flu Vaccine Developed in Oxford. Accessed at www.oxfordbrc.org/media/news/517/
12. Before It’s News. Universal Flu Vaccine Human Clinical Trials Report Success, Feb. 7, 2011. Accessed at m.beforeitsnews.com/story/401/375/ Universal_Flu_Vaccine_human_clinical_trials_reports_success.html.
Trudie Mitschang is a staff writer for BioSupply Trends Quarterly.
Vaccines have long led the arsenal in our battle against disease. Clearly, many public health achievements can be attributed to immunization, but the future success of the vaccine industry will not hinge on development alone. Challenges in funding, research, storage and distribution are factors as well. Even as the medical world celebrates the successful clinical trials for vaccines to treat diseases like HIV/AIDS, countries most impacted by such epidemics are often too impoverished to afford them. In many of these regions, infrastructures for vaccination are so poor or nonexistent that even currently available vaccines cannot be successfully delivered. Today’s medical researchers are tasked with improving the effectiveness of existing vaccines, developing new vaccines, lowering costs and innovating delivery methods to ensure that lifesaving vaccines can reach the population groups that need them most.