If “work” means prevent every single infection, then no.
COVID-19 vaccines are not 100% effective at preventing infection.
But if “work” means reduce the risk of severe illness, hospitalization and death, the evidence is much stronger.
The CDC reports that COVID-19 vaccination reduces the risk of critical illness and hospitalization, although the amount of protection changes over time.
WHO likewise states that COVID-19 vaccines continue to provide protection against severe disease and death.
This is an important distinction.
A person can test positive while vaccination is still providing meaningful protection against the worst outcomes.
What About Long COVID?
Another important concern is what happens after the initial infection.
Some people experience persistent symptoms following COVID-19, sometimes referred to as Long COVID.
These symptoms can affect different parts of the body and can continue well beyond the initial infection.
According to the CDC, studies indicate that people who are vaccinated and later develop COVID-19 are less likely to develop Long COVID compared with people who are unvaccinated or not up to date with vaccination.
That does not mean vaccination eliminates the possibility of Long COVID.
It means vaccination may reduce the risk.
Again, the distinction between zero risk and lower risk is essential.
Why Some Headlines Create Confusion
Social media rewards short, emotional statements.
A headline such as:
“Vaccinated people can still get COVID!”
is technically true.
But it leaves out essential context.
A more complete statement would be:
“Vaccinated people can still become infected with COVID-19, but vaccination continues to reduce the risk of severe disease and death.”
That second version is less dramatic.
It is also much more informative.
The same problem occurs in reverse.
A headline saying:
“Vaccines prevent COVID-19!”
could also be misleading if readers interpret it as meaning that vaccinated people can never become infected.
Neither extreme accurately describes the situation.
What Should People Do If They Develop Symptoms?
If a vaccinated person develops symptoms that could be caused by COVID-19, vaccination status should not automatically be used as a reason to dismiss those symptoms.
A person may still have COVID-19.
Depending on the circumstances, testing can help determine whether SARS-CoV-2 is responsible.
