What's the greatest medical development of the last century? Open-heart surgery? The discovery of penicillin? Laser hair removal?
According to experts, the answer is clear: vaccinations.
"Immunizations are the greatest medical advance of the last one hundred years," says Richard L. Wasserman, MD, PhD, clinical professor in the department of pediatrics at the University of Texas Southwestern Medical School in Dallas.
"There's no question that immunizations have done more good for more people than any other medical intervention," agrees Ricardo U. Sorenson, MD, chair of the department of pediatrics, Louisiana State University Health Sciences Center in New Orleans.
Vaccinations have essentially wiped out diseases that once infected hundreds of thousands of people every year and killed tens of thousands. Yet many of us take immunizations for granted and may assume that, once we're adults, we don't need them anymore. We do. While we may outgrow our need for booster chairs, we never outgrow our need for booster shots. So if you suspect you're not up-to-date with your vaccinations, it's time for a checkup.
Why Get Immunized?
Vaccines don't get the credit they deserve -- a testament to their success. Vaccines have so effectively wiped out many diseases that these illnesses seem as extinct as dinosaurs.
"How many people do you know who have had diphtheria or tetanus?" asks Wasserman. "Probably none. That's how well vaccines work."
Sorenson agrees that, nowadays, we have a casual attitude toward the diseases that terrified our grandparents. "People tend to forget how serious diseases like measles, mumps, rubella, and whooping cough were because they haven't experienced them," he tells WebMD.
But what's risky about our casual attitude is that these diseases are not extinct. In some parts of the world, they're common. If people stopped getting vaccinated in the U.S., they would become common here.
"I've seen the results of not getting vaccinated," says Wasserman. "I've seen children sick with vaccine-preventable diseases, like whooping cough and polio. It's tragic."
Why Do Adults Need Vaccinations?
Many vaccines work by introducing a dead or weakened version of a germ into your body, allowing your body to become familiar with it. Your immune system then reacts by creating antibody proteins custom-designed to fight that particular microbe. Then, if you ever come into contact with the real germ, the antibodies attack it. This is how vaccines grant you immunity.
However, that immunity doesn't necessarily last forever. Those antibodies may fade away with time.
"After age 30 or so, the potency of immunity wanes," Wasserman says. "In the same way that your muscle strength fades after middle age, the vaccine immunity that protected you when you were young loses its strength when you're in your 40s, and 50s, and 60s."
Happily, the solution is simple: get a booster shot. This is a way of reminding your immune system how to fight the microbe.
In addition to boosters, you need other vaccines as you get older and your risk of getting certain diseases increases.
Vaccinations Benefit Others
Obviously, getting a vaccination protects you from getting sick, but vaccines have a greater benefit: they protect the people around you from getting sick.
It's a phenomenon called "herd immunity." If most people in a group are vaccinated against a disease, even the people who aren't vaccinated are much less likely to get it.
This reason for vaccination is important, because vaccines can be dangerous for some people. For instance, some are too sick to handle a vaccine or are allergic to it, but if the people around them are vaccinated, they are more likely to be safe. "It's an indirect way of protecting them," says Wasserman.
There's also a flip side. If you live with someone with a compromised immune system from a disease or its treatment -- like chemotherapy -- tell your doctor before you get vaccinated. The weakened version of a virus in a vaccine could spread from the vaccinated person to the ill family member. Sometimes, even the weakened virus is dangerous for a person with a compromised immune system.
Which Immunizations Do Adults Need?
The vaccinations you need depend on your age, health, and vaccination history. But here's a rundown of some of the common vaccines adults should get.
Diphtheria and tetanus. Diphtheria can cause breathing problems, paralysis, and heart failure. Tetanus can cause severe and dangerous stiffening of the muscles throughout the body.
The CDC recommends that all adults have a diphtheria/tetanus booster shot every ten years. "Diphtheria is still a rare disease these days, but it's most common in people over 65," says Wasserman. "Continued vaccinations are important."
Influenza (Flu) vaccine. The CDC recommends that all people 50 and over get the flu vaccine annually, but it's also a good idea for adults of any age. While you may think of the flu as just an annoyance, it can be a serious, even fatal, illness. The CDC estimates that about 36,000 people in the U.S. die from the flu every year.
While the injected vaccine is standard, Wasserman is impressed with the more recent inhaled flu vaccine. "It seems to work even better than the injected vaccine and causes fewer side effects," he says.
Hepatitis A. Hepatitis A is spread by contact with contaminated food or fluids and can cause serious liver disease. The CDC recommends vaccinations for adults who use injected street drugs, men who have sex with men, and people with liver disease and other illnesses.
Most cases of hepatitis A are mild but some result in severe illness, requiring an emergency liver transplant. "The hepatitis A vaccine protects against a rare but potentially devastating illness," says Wasserman.
Hepatitis B. Hepatitis B can lead to chronic liver disease and other problems. In the U.S., 80,000 people get it each year and 4,000-5,000 die. Hepatitis B is spread by contact with bodily fluids, and is most commonly spread by sex or infected needles.
The CDC recommends the HBV vaccine for adults who have an increased risk of getting the disease because of their job or lifestyle.
Pneumococcal vaccine. The CDC recommends all people 65 and older get this vaccine, which protects against serious bacterial infection of the lungs, brain, and blood.
"I think that people who are middle-aged or older should get the pneumococcal vaccine," says Wasserman. "Pneumococcal pneumonia is a major cause of illness in older folks ... A lot of people who are said to die from flu actually die from the pneumococcal pneumonia that follows the flu."
Future Adult Vaccines
In addition to the vaccinations above, a few vaccines are likely to be available soon.
HPV (human papillomavirus.) HPV is a very common virus which can be transmitted by physical and sexual contact. While it is not harmful in itself, certain strains can lead to cervical cancer, so a vaccine that prevents HPV has tremendous implications.
"It's amazing," says Wasserman. "What could be greater than a vaccine that actually prevents a form of cancer?"
The vaccine, Gardasil, is 100 percent effective against four common strains of HPV that cause about 70 percent of all cervical cancers. It has been recommended for approval by an FDA advisory panel and a final decision is expected this month. Another HPV vaccine, Cervarix, is in development.
Shingles. Shingles is a painful disease caused by the varicella virus, which also causes chickenpox. A new vaccine for shingles -- Zostavax -- is actually just a double dose of the chickenpox vaccine. As of May 2006 it has not yet been FDA-approved.
"The initial report on the shingles vaccine is very encouraging," says Wasserman. "Shingles is a terrible disease, especially for older people."
Many other vaccines are in much earlier stages of development, including:
Strep. Some preliminary research into a vaccine against Group A streptococcus shows promise. One study found that, in a group of 28 healthy adults, the vaccine seemed safe and appeared to trigger an immune response.
Genital Herpes. Researchers are also working on vaccines against genital herpes. Two 2002 studies found that one vaccine radically reduced the rate of herpes infection in women who were not previously infected with the virus.
However, in women who already had the common herpes virus that causes cold sores the vaccine had no effect. Strangely, the vaccine had no effect in men.
Taking Charge of Your Health
Given the importance of regular adult vaccinations it's crucial to keep track of your immunization history and stay current with your vaccinations.
Unfortunately, many people don't. They simply assume their doctor will tell them when they need a shot, but that's not necessarily the case. Most people change doctors many times in their lives and their current doctor may have no idea about their immunization history.
So from now on, make a note when you get a vaccination. If don't know which vaccinations you've had recently, talk to your doctor. To be on the safe side, it may be time for you to roll up that sleeve, stick out your arm, and wince.
By R. Morgan Griffin, reviewed by Louise Chang, MD
SOURCES: Centers for Disease Control, National Immunization Program web site, "Polio vaccine: What you need to know," "Tetanus and diphtheria vaccine (Td)," "Pneumococcal polysaccharide vaccine: What you need to know," "Inactivated Influenza Vaccine: What you need to know," "Hepatitis B Vaccine: What you need to know," "Hepatitis A Vaccine: What you need to know." Centers for Disease Control web site, "Genital HPV Infection -- CDC Fact Sheet." GlaxoSmithKline web site. Hildegund C. J. Ertl, MD, program leader, Immunology Program, the Wistar Institute, University of Pennsylvania. Kotloff, KL et al. JAMA, August 11, 2004; vol 292: pp 709-15. National Institute for Allergic and Infectious Diseases web site, "Understanding Vaccines: What They Are and How They Work." Ricardo U. Sorensen, MD, chair, department of pediatrics, Louisiana State University Health Sciences Center, New Orleans; member of the American College of Allergy, Asthma & Immunology Basic & Clinical Immunology Committee. Stanberry, LR et al, NEJM, November 21, 2002; vol 347: pp 1652-1661. Richard L. Wasserman, MD, PhD, clinical professor in the department of pediatrics at the University of Texas Southwestern Medical School; member of the Member of the American Academy of Allergy Asthma & Immunology. WebMD Medical News: "Cervical Cancer Vaccine Shows Promise." WebMD Medical News: "FDA Backs Shingles Vaccine."