What Are Antibiotics, and How Are They Different from Vaccines?
Key takeaways:
Antibiotics are life-saving medications that fight bacterial infections. Vaccines are medicines that prevent you from getting sick.
Vaccines strengthen your immune system so infections are less likely to start, whereas antibiotics fight an infection that’s already making you sick.
Antibiotics and vaccines both have important roles in managing infectious disease. They complement each other and help keep you and your loved ones safe and healthy.
What’s the best way to manage infections? Well, it depends. Infections are caused by different types of germs, so management of the infection depends on what germ is causing the issue.
Antibiotics are medications that treat infections caused by bacteria. They work by stopping bacteria from replicating or making copies of itself. Many ear infections, urinary tract infections (UTIs), and pneumonia cases are due to unwanted bacteria.
Vaccines, on the other hand, prevent infections rather than treat them. Common examples include hepatitis B, varicella, and COVID-19 vaccines.
Antibiotics and vaccines are both key reasons why many scary infections aren’t around now as much as they used to be — and why others are highly treatable. But do they work together?
What are antibiotics?
Antibiotics are a large class of medications that treat bacterial infections. There are many types, and they each work in their own unique way. Penicillin antibiotics, fluoroquinolones, macrolides, and more are all available for you to use.
The type and location of your infection will guide your antibiotic treatment. Different types of antibiotics treat different types of bacteria. So an antibiotic used to treat an ear infection may not be effective at treating a UTI — and vice versa.
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Antibiotics are administered in a variety of ways, as well. Many are taken by mouth, some are inhaled, and others are topically applied to the skin. In the hospital, they’re more often injected into a vein. The right formulation helps deliver the drug to the site of infection quickly and effectively.
Despite differences in the way they work, it’s important to remember that all antibiotics only fight bacteria. They can’t kill viruses, fungi, or parasites.
How do antibiotics fight infections?
Antibiotics can be divided into two main groups depending on how they treat an infection: bactericidal and bacteriostatic antibiotics.
Examples of bactericidal antibiotics that work by directly killing bacteria:
Penicillin (Penicillin VK)
Ciprofloxacin (Cipro)
Examples of bacteriostatic antibiotics that work by slowing bacteria down, giving your immune system time to catch up:
Azithromycin (Zithromax)
Doxycycline (Vibramycin, Doryx)
Because antibiotics attack bacteria that are living in your body, they’re most effective when you’re already sick with an infection. This is different from vaccines, which shield you from bacteria or viruses that you might encounter in the future.
What are vaccines?
When you’re exposed to a germ that makes you sick, your immune system fights to get rid of it. At the same time, your immune system takes a “snapshot” so it can recognize the germ in the future. This allows your body to fight off the germ more easily if it encounters it again.
Vaccines use this same concept. By giving your body a “snapshot” of a germ, your immune system can learn about it and defend against it without you getting sick.
There are many vaccines that can prevent a number of diseases in both children and adults. Although vaccines can cause temporary discomfort and generally mild side effects, they’re better than managing a potentially serious infection.
How do vaccines fight infections?
Some vaccines prevent bacterial infections, while others prevent viral infections.
When you receive a vaccine, your body is introduced to harmless pieces of bacteria or virus. This introduction gives your body a heads-up about germs that could be a threat if you encounter them in the future. Your immune system takes note of these possible intruders so it can respond quickly if you’re exposed to them later.
After you’re vaccinated, your immune system is “all hands on deck” all throughout your body — on the surfaces in your mouth, nose, and eyes, inside your stomach and gut, and circulating in your bloodstream — ready to defend at the first sign of infection.
Remember, though, that vaccines rely on your immune system to build a strong defense. They work best if you take them while you’re healthy.
Antibiotics vs. vaccines: What’s the difference?
Although antibiotics and vaccines both aim to keep you healthy, they do so in different ways. One major difference: prevention versus treatment.
Vaccines are given in advance. They teach your immune system how to fight germs to prevent infection upon exposure. These germs can include viruses and bacteria.
Antibiotics, on the other hand, treat active infections. These medications are only effective at stopping infections caused by bacteria. They do not treat viral infections.
Is it true that some vaccines contain antibiotics?
Yes. Confusingly, some vaccines contain tiny amounts of antibiotics. Antibiotics are sometimes added to vaccines to keep bacteria from contaminating them during the manufacturing process. This same approach is used by food packagers to keep germs out of pre-packaged foods.
The tiny amount of antibiotics used in vaccines are safe for humans. But they won’t kill many bacteria in your body. The amount is too small to have any effect on bacteria trying to make you sick.
Can vaccines cause antibiotic resistance?
No. Vaccines don’t cause antibiotic resistance. Antibiotic resistance is when bacteria develop tricks to evade an antibiotic. Antibiotic-resistant bacteria are much harder to treat than other bacteria.
Instead, vaccines help fight it. They prevent germ colonies from growing and learning any resistance tricks in the first place.
Antibiotics, vaccines, and COVID-19
Let’s say it’s time for your COVID-19 vaccine. But you’re currently taking antibiotics for another infection. It’s reasonable to wonder if your immune system is up for building immune defenses while fighting an infection with antibiotics.
Can I get a vaccine while I’m receiving antibiotics?
Yes, although you might want to wait a few days.
If you’re taking antibiotics for an illness and you’re scheduled to get a vaccine, you can still get it. But, if you’ve got some flexibility in your schedule, it might make sense to delay the vaccine. That’s because vaccines can trigger a fever, body aches, or chills, and that’s probably not what you need if you’re already feeling lousy.
Plus, there’s a chance vaccine side effects could make things confusing. If you get a fever from the vaccine while you’re taking antibiotics, you might wonder whether the antibiotics are working. It could be hard to tell whether you’re recovering from your illness the way you should.
That said, getting a vaccine while you’re taking antibiotics isn’t dangerous. The vaccine will still work to do its job, and so will the antibiotics.
Can I get a vaccine if I have COVID?
No. Getting vaccinated usually means visiting a healthcare provider or pharmacy. If you have COVID-19, that could put other people at risk of catching it from you. The CDC recommends at least waiting until you have completed your isolation period.
However, having COVID can also provide some natural immunity to the virus. After having COVID, you may want to wait about 3 months to get your vaccine (or 4 to 6 months for a booster).
Do antibiotics work against COVID?
No. COVID is caused by a virus — not bacteria. Antibiotics aren’t effective against viruses like the coronavirus.
The bottom line
Vaccines strengthen your immune system before you get sick. Antibiotics, on the other hand, fight active infections caused by bacteria. Although they work differently, vaccines and antibiotics both have important roles to play when it comes to keeping you safe from infectious disease.
Why trust our experts?
References
American Academy of Pediatrics. (n.d.). Vaccine preventable diseases.
Baquero, F., et al. (2021). Proximate and ultimate causes of the bactericidal action of antibiotics. Nature.
Centers for Disease Control and Prevention. (2023). Child & adolescent immunization schedule.
Centers for Disease Control and Prevention. (2023). COVID-19: Frequently asked questions.
Centers for Disease Control and Prevention. (2023). Isolation and precautions for people with COVID-19.
Centers for Disease Control and Prevention. (2022). Vaccines by disease.
Centers for Disease Control and Prevention. (2020). Possible side effects from vaccines.
Immunize.org. (2022). Contradictions and precautions.
Loree, J., et al. (2022). Bacteriostatic antibiotics. StatPearls.
Micoli, F., et al. (2021). The role of vaccines in combatting antimicrobial resistance. Nature.
Office of Infectious Disease and HIV/AIDS Policy (OIDP). (2022). Vaccine types.
U.S. Food and Drug Administration. (2019). Common ingredients in U.S. licensed vaccines.
