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Vaccines have been in the news a lot lately. But what are they, how do they work, and why should you or your child get vaccinated? Here’s some helpful background.
Vaccines and immunity
When disease-causing germs enter your body and start to multiply, your immune system swings into action, creating proteins called antibodies to destroy them. If your immune system hasn’t seen the germ before, it may not be able to produce antibodies quickly enough to keep you from getting sick. If that’s the case, your antibodies will fight the germs to help you get well.
Once your body has produced antibodies against a particular germ, they remain in your system — sometimes for years — ready to destroy those germs if they ever try to invade again. This keeps you from becoming ill; it’s referred to as immunity.
Vaccines are a kind of training drill for your immune system. They help it learn to recognize a particular kind of germ and create antibodies to fight it before you even come in contact with it — so you become immune without having to get sick first.
How vaccines came about
People have used vaccines to prevent disease for hundreds of years. It’s believed to have started with smallpox. In 1796, an English doctor named Edward Jenner noticed that milkmaids who had gotten cowpox didn’t seem to get smallpox. So, he scratched cowpox material into the arm of a young boy and exposed him to smallpox several times. The boy never got smallpox.
Over time, scientists have developed much more sophisticated ways of helping people develop immunity to illness. They’ve made vaccines from dead or weakened versions of the germ that causes a disease, pieces of the germ itself, or a harmful substance it produces. More recently, scientists have used altered versions of different viruses to protect against viruses that cause illness. The new mRNA vaccines for COVID-19 work by making proteins that cause an immune response.
Vaccine success stories
Smallpox is just one of several diseases we no longer worry about — thanks to vaccines. It was a serious illness that killed 3 in 10 people who got it and caused severe scarring in those who survived. This ancient disease (its signs have been found on 3,000-year-old Egyptian mummies) was still considered widespread as recently as 1966. But thanks to a global vaccination effort, the World Health Assembly declared the world smallpox-free in 1980.
Polio, which can invade the spinal cord and lead to paralysis, was widely feared in the U.S. in the 1940s and 50s. At one point, it disabled an average of 35,000 people a year. Today, polio has been eliminated in the U.S. as a result of vaccination. But it still exists in other countries and could be brought here by travelers, which is why we continue to vaccinate against it.
Other diseases that are no longer a serious threat because we can vaccinate against them include:
- Tetanus, which causes painful muscle stiffness and can be fatal
- Hepatitis B, which can cause chronic infection in babies
- Rubella, which can cause miscarriage or serious birth defects
- Measles, which is so contagious that it can spread when someone enters a room up to two hours after an infected person has left it
- Whooping cough (pertussis), which can be deadly to babies
Another success story is influenza — the flu — which can be severe enough to result in hospitalization or even death. An annual flu shot can prevent you from getting the flu or make your illness less severe if you get it. The CDC estimates the flu vaccine prevents tens of thousands of hospitalizations every year!
Now, there are also vaccines available for COVID-19, the pandemic disease that is caused by a new kind of coronavirus and has led to more than 30 million cases and more than 550,000 deaths in the U.S. to date. There are currently vaccines authorized for use in the U.S. to prevent COVID-19. They have been proven safe and effective at keeping people from getting COVID-19, or from becoming seriously ill if they do get the disease.
Before vaccines can be used in the U.S., they must go through legally required safety testing and approval processes. The first step is laboratory testing. Based on lab results, the FDA decides whether it’s okay to test the vaccine in people. If so, testing takes place in three phases, starting with small groups of volunteers and expanding to larger groups. These tests help researchers determine whether the vaccine is safe, how well it works against the disease, what common reactions may occur, and what the dose(s) should be.
The FDA then reviews the information from the tests and inspects the manufacturing plant before authorizing the vaccine for use. But safety measures don’t end there. After authorization, the FDA monitors vaccine safety by conducting periodic inspections of the manufacturing plant; it can also require the vaccine maker to submit samples from each lot for testing or to submit the results of its own testing. Together, the FDA and CDC also monitor vaccine safety through the Vaccine Adverse Event Reporting System, where anyone can report a possible vaccine side effect.
Why get vaccinated?
When you get a vaccine, you’re not just protecting your health. You’re also protecting others. If enough people in a community are vaccinated against a disease, it’s harder for germs to find someone to infect — which can slow or stop an outbreak. This is called community immunity. And because some people can’t get vaccinated — for example, people with serious allergies or certain health conditions that weaken their immune systems — community immunity helps protect them.
Have questions about vaccines? Talk to a doctor >