Are vaccines safe—and how necessary are they?

A Mid-Atlantic Permanente Medical Group doctor answers the most-asked questions about vaccines.

doctor injecting african american woman with vaccine
Photo by CDC

By Nhat M. Doan, M.D.

As an infectious disease specialist, I consider vaccines to be among the most important tools in my arsenal to prevent serious illness.

Vaccines help your body produce the antibodies you need to fight off common infections. Thanks to vaccines, we completely eradicated smallpox, which at one time killed seven in 10 victims and blinded or severely scarred many of the rest. Thanks to vaccines, once-common diseases that killed or disabled thousands of infants and children every year—including whooping cough, polio, measles, rubella, Hib (which commonly causes meningitis) and diphtheria—now occur so rarely in the United States most doctors have never seen a case of them.

In my practice, I see a lot of transplant patients and adults with HIV who may be especially vulnerable to infection, and I tell them that staying up to date with their vaccines is one of the most important things they can do to protect their health.

Unfortunately, many patients are still skeptical of vaccines. I see this especially with the flu shot. Patients will invariably recall the time they or a loved one came down with the flu right after getting the flu vaccine. And they cling to this as proof that the flu vaccine was the culprit.

The evidence is clear: You cannot get the flu from a flu shot, which is usually made of an inactivated (dead) version of the virus, or even the nasal flu vaccine, which contains a live but severely weakened virus. Unfortunately, these patients don’t want to hear the reality that the illness they experienced was most likely a case of the common cold they contracted around the time of the vaccination. It’s certainly possible to get the flu as well within the two weeks of getting the flu shot, while the body is making an antibody response. But this scenario would be rare.

Another argument I hear is that the flu shot is not that effective. And I agree that it is not a perfect vaccine. Flu viruses change constantly, and each year’s flu vaccine is created in an elaborate process in which scientists from all over the world survey flu outbreaks and make their best collective guess about which viruses to target in the upcoming flu season. The U.S. Centers for Disease Control and Prevention (CDC) estimates that the flu shot is between 40% and 60% effective, depending upon how well the vaccine matches the season’s outbreaks. Despite this, the CDC, which does extensive surveillance, reports that the flu vaccine prevents tens of thousands of hospitalizations and thousands of deaths from the flu every year—at least in part because flu symptoms are usually not as severe in people who have been vaccinated.

So, even though 40% to 60% effectiveness may not sound impressive, it is still much better than 0% protection if you were to skip the vaccine altogether.

A Lifelong Process

Who should get vaccinated, against what—and when?

Vaccination is a lifelong process. Infants and small children are routinely vaccinated in the U.S. for more than a dozen diseases and are usually required to have completed most of their vaccinations before they attend school and other group activities. Consult your pediatrician about the recommended vaccination schedule for your child.

Doctors also recommend that teens who may have missed some of their early childhood immunizations be vaccinated for diphtheria, tetanus and whooping cough or pertussis (the Tdap vaccine), measles, mumps and rubella (the MMR vaccine), hepatitis A and B, meningococcal disease, chickenpox and polio. Teens, both boys and girls, should also be vaccinated for the sexually transmitted human papillomavirus (HPV), which has been linked to cancers of the cervix, vagina, anus and penis.

It is recommended that every adult have the Tdap vaccine if they didn’t have it as an adolescent, and then receive a Td (tetanus, diphtheria) booster shot every 10 years. And the CDC recommends that everyone 50 or older have the shingles vaccine, which is delivered in two doses two to six months apart, and that everyone 65-year-plu-old patient (earlier if you are a smoker or your doctor recommends it for other reasons) have the pneumococcal vaccines, which prevent some types of pneumonia, meningitis and sepsis.

If you are traveling outside the country, you should check with your doctor about vaccinations that are both required and “highly recommended” for the regions you’ll be visiting.

Some people should not be vaccinated, but this is a decision you should make with your doctor on a case-by-case basis. Every vaccine comes with different caveats. Infants under 6 months should not have the flu vaccine, for instance. Anyone who has had an allergic reaction to a vaccine or is allergic to certain components of vaccines should talk to their doctor before being vaccinated. Patients with severely compromised immune systems should consult their doctor before being vaccinated. And anyone currently fighting an infection should usually wait to be vaccinated.

Vaccines are extremely safe and go through years of testing before they are approved by the U.S. Food and Drug Administration. Serious side effects with vaccines are extremely rare. As I tell my patients, I am very comfortable following CDC guidelines for getting vaccinated and getting my family vaccinated. Perhaps one day we will render certain vaccines unnecessary, completely eradicating polio, for instance, the way we eradicated smallpox long ago.

But, in the meantime, getting vaccinated is an easy way to protect not only your own health, but the health of your friends and family and neighbors who, for whatever reason, cannot be vaccinated themselves.

For more information about vaccines and preventable diseases, including schedules of recommended vaccines by age group, visit the CDC’s website. The CDC also offers an informative page that dispels misconceptions about the flu vaccine.

Nhat M. Doan, M.D., is a board-certified infectious disease specialist with the Mid-Atlantic Permanente Medical Group. He sees patients at the Kaiser Permanente Springfield Medical Center.

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