Fact check: Vaccines do protect against viral infection

Shared tens of thousands of times on Facebook, posts suggest that a vaccine cannot fight a virus because a virus must “run its course.” This claim, spread as trials for a COVID-19 vaccine are underway around the world, is false.

Reuters Fact Check. REUTERS/Axel Schmidt

Examples of these claims can be found here , here , and here .  

Vaccines can be developed for bacterial or viral infections. As explained here by the Centers for Disease Control and Prevention (CDC), vaccines are used to prevent, rather than treat, infection, “working with the body’s natural defenses to safely develop immunity to disease.” Vaccines mimic an infection, causing the body to produce antibodies and defensive white blood cells, in order to help develop immunity.  

The CDC says that a scientist’s approach to a given vaccine depends on whether the infection the vaccine will prevent is caused by a virus or by bacteria. There are also “practical considerations, such as regions of the world where the vaccine would be used,” which are “important because the strain of a virus and environmental conditions, such as temperature and risk of exposure, may be different across the globe.” ( here ) 

Different types of vaccines include live, attenuated vaccines; inactivated vaccines; toxoid vaccines; subunit vaccines; and conjugate vaccines. More information on how each kind works can be found here , provided by the CDC, and , provided by the U.S. Department of Health & Human Services (HHS).  

Vaccines have been successful in helping to eliminate diseases formerly prevalent in the United States. Viruses prevented by vaccines include polio, Hepatitis A, Hepatitis B, smallpox, measles, mumps, rubella, and rotavirus. Examples of bacterial infections prevented by vaccines include tetanus and pneumococcal disease ( here , here ). 

The claim that doctors do not administer vaccines for viruses because viruses need to run their course may stem from a confusion between vaccines and antibiotics. As explained here by the Mayo Clinic, antibiotic drugs typically fight bacterial infections, “but they aren't effective against viruses.”  

“Antibiotics cannot kill viruses because bacteria and viruses have different mechanisms and machinery to survive and replicate. The antibiotic has no ‘target’ to attack in a virus,” according to ( here ).  

In fact, the U.S. Food & Drug Administration (FDA) warns against using antibiotics when you have a virus, as they “can put you at risk of getting a bacterial infection that is resistant to antibiotic treatment” ( here ).  

Certain viral infections, like the common cold, do not have available vaccines. Since they are caused by viruses, they cannot be treated with antibiotics, and, without available antiviral medications, they must “run their course.” (here , here ). 

The current scientific approach to finding a cure for COVID-19 involves the search for a variety of treatments. Currently, more than half a dozen drugmakers around the world are conducting advanced clinical trials, each with tens of thousands of participants, and several expect to know if their COVID-19 vaccines work and are safe by the end of 2020 ( here ).  

Meanwhile, pharmaceutical companies and labs are working to develop antiviral treatments for COVID-19. “Since the coronavirus that causes COVID-19 is new,” however, “there is limited evidence regarding specific antivirals that may work against it,” according to the Johns Hopkins University School of Medicine ( here ). One antiviral candidate is Remdesivir, an experimental COVID-19 drug currently used under emergency authorization ( here ).  

Beyond the quest for a vaccine and effective antiviral medications, other treatments currently being tested for the novel coronavirus include monoclonal antibodies, dexamethasone, and convalescent blood plasma therapy. More information about them can be found here .  


False. Vaccines are used to successfully prevent some viruses and bacterial illnesses. Antibiotics, on the other hand, typically treat bacterial rather than viral infections.

This article was produced by the Reuters Fact Check team. Read more about our fact checking work  here .