Share on Pinterest
The figures so far show that your chances of getting COVID-19 after vaccination are less than 1 percent. Jon Cherry/Getty Images
  • People who get COVID-19 after vaccination represent about 1/100th of 1 percent of those who’ve been inoculated.
  • Experts say this is because although the vaccines are highly protective, they’re not 100 percent effective.
  • They add that people who do become sick after getting vaccinated have a far lower chance of being hospitalized.

The fact that vaccinated people can still get COVID-19 should not be a surprise.

And it’s certainly no reason not to get vaccinated.

“Breakthrough” cases of COVID-19 among vaccinated people are expected.

It doesn’t mean that the vaccines currently in use are not highly effective.

They are.

They’re just not 100 percent effective.

So, yes, you can still get sick even if you’re vaccinated, but it’s exceedingly rare.

According to the Centers for Disease Control and Prevention (CDC), 87 million Americans had received the COVID-19 vaccine as of April 20, 2021. Among vaccinated people, there were 7,157 breakthrough cases, with fewer than 500 hospitalizations and 88 deaths.

Do the math and you can see the cases are about 1/100th of 1 percent of those vaccinated.

“The effectiveness of any vaccine in preventing serious illness is high, and in the case of the COVID-19 vaccines, it’s very high,” Dr. S. Wesley Long, an infectious disease researcher and clinical microbiologist at Houston Methodist in Texas, told Healthline.

“All the data shows that if you’re vaccinated you probably won’t get any symptoms at all, but even if you do, you still probably won’t get full-blown COVID and end up in the hospital,” he said.

COVID-19 vaccine effectiveness varies according to which shot you get.

Research published this month by the CDC shows that messenger RNA (mRNA) vaccines against COVID-19 — which include those developed by Moderna and Pfizer-BioNTech — are 80 percent effective in preventing detectable coronavirus infections 14 days after the first dose and 90 percent effective after the second dose.

The single-dose Johnson & Johnson vaccine was found to be 66 percent effective at preventing laboratory-confirmed COVID-19 illness 2 weeks after vaccination.

The Johnson & Johnson vaccine, based on more conventional adenovirus technology, was also found in clinical trials to be 100 percent effective against serious COVID-19 illness.

In the study, several people in the control group were hospitalized and/or died from COVID-19.

None of those who received the vaccine were hospitalized or died, even among those who got detectable infections.

So, why can people who get vaccinated still get sick?

To begin with, 66 percent or 80 percent or 90 percent effective isn’t the same as 100 percent effective.

You can also get sick if you’re exposed to the coronavirus in the weeks immediately following your shot, when the immune response caused by the vaccine is still developing.

“There is [also] a small subset of people who will not make a protective response after immunization,” Long said. “That’s why we need herd immunity to protect those people.”

That said, the vaccines for COVID-19 are remarkably effective.

Since the 2009–10 flu season, for example, the effectiveness of the flu vaccine has ranged from 19 to 60 percent.

“The COVID vaccines do very well, especially when compared to something like the influenza vaccine,” Long said.

How well?

Consider that when the Food and Drug Administration (FDA) issued guidelines for emergency use authorizations for COVID-19 vaccines, it set the efficacy threshold at just 50 percent.

All three vaccines now in use in the United States far exceed that minimum.

“We [also] have evidence to suggest that the vaccines do a pretty good job of preventing transmission of the disease to other people,” Long said.

Breakthrough cases in vaccinated people are entirely normal.

“There will be a small percentage of people who are fully vaccinated who still get sick, are hospitalized, or die from COVID-19,” the CDC states.

“Even if we have a handful of breakthrough cases it’s important to remember that these people are unlikely to have severe disease or pass COVID along to other people,” Long said.

The latest data from the CDC, for example, shows that the Pfizer-BioNTech and Moderna COVID-19 vaccines were 94 percent effective against COVID-19 hospitalization among fully vaccinated adults ages 65 and older — the population considered most vulnerable to the disease — and 64 percent effective among partially vaccinated adults.

That’s similar to what’s already known about the flu.

A study published in 2018 found that even when people who got the flu shot fell ill, their odds of being hospitalized were reduced by 37 percent compared with unvaccinated people. The odds of requiring intensive care were cut by 82 percent.

To recap:

If you get vaccinated, the odds are you won’t get COVID-19.

If you get vaccinated and you do get sick, the odds are you won’t get seriously ill or die from the disease.

It’s not a 100 percent guarantee, but it’s close.