Breakthrough symptoms of COVID-19: How will you know if you’ve got a breakthrough infection?

Aug. 26, 2021
Breakthrough symptoms of COVID-19 can be milder than original COVID-19 infections. Here a Latino man looks serious.
Breakthrough symptoms of COVID-19 can be milder than symptoms unvaccinated people experience. You might only have a headache. Experts say: “Get tested.” Photo: Getty Images.

Breakthrough cases of COVID-19 are rare, but on the rise as the highly transmissible delta variant causes a dramatic increase in positive cases of COVID-19.

If you’re fully vaccinated and feeling a little sick, how will you know if you have a breakthrough case of COVID-19?

It can be tricky because symptoms in breakthrough COVID-19 cases can be different from symptoms of COVID-19 in unvaccinated people. Breakthrough COVID-19 symptoms can be milder.

It’s also possible to have a breakthrough case of COVID-19 and to be asymptomatic or, in other words, to have no breakthrough symptoms at all. So, what should you do if you’ve got the sniffles, body aches, a cough or what feels like a stomach bug?

Breakthrough COVID-19 cases

Dr. Michelle Barron is the senior medical director of infection prevention and control for UCHealth and one of the top infectious disease experts in Colorado. She encourages people who are feeling sick to consider whether any of their symptoms are typical for them. For instance, do you typically get headaches or seasonal allergies? If not, consider COVID-19 as a possible culprit for your symptoms.

And, if you have any doubts about whether you might have breakthrough symptoms of COVID-19, get tested.

Recently, a friend of Barron’s, who has already had COVID-19 and is fully vaccinated, complained of a severe headache.

Barron grilled her friend, who was reluctant to bother getting a COVID-19 test.

“She was going through the list of symptoms and said, ‘It’s only a headache. I don’t have a runny nose. I don’t have a sore throat. I still have taste and smell. I can eat fine.’” Barron recalled. “She had no respiratory symptoms, nothing else.”

Even so, Barron noticed that her friend’s key symptom was unusual for her.

“You don’t normally get headaches,” Barron said. “Stop talking to me and go get your test.”

Barron’s friend has an underlying health condition that makes her more vulnerable to severe illness from COVID-19, and she’s a health care provider, so she’s especially cognizant of not wanting to expose patients to COVID-19.

So, the friend got her COVID-19 test. And Barron’s hunch was right. The test confirmed a breakthrough COVID-19 case. She’s now quarantining at home and recovering.

So, if you feel sick, Barron urges you to consider whether you might have breakthrough symptoms of COVID-19.

“If you normally don’t have allergy symptoms and suddenly you do, you might have COVID-19, especially if you’ve been vaccinated. You could have a breakthrough infection,” Barron said.

If you have any doubts, isolate yourself from other people and strongly consider getting a COVID-19 test.

“We have plenty of tests now. The threshold for getting tested should be low. Even if you’re fully vaccinated, consider getting tested if you’re having any symptoms,” said Barron, who is also a professor of medicine and infectious diseases at the University of Colorado School of Medicine on the Anschutz Medical Campus.

“Get tested. You could have a cold and be just fine, but it also could be COVID-19 and there are implications for that,” Barron said.

Barron, herself, has gotten tested for COVID-19 recently. She has seasonal allergies and that’s typical for her. But, the sniffling and sneezing has been horrible lately. So, just to be on the safe side — and to protect her vulnerable patients — she got tested and thankfully, does not have COVID-19.

“I wanted to be sure. I don’t want to just say I have allergies and take the risk of exposing my patients,” Barron said.

Barron also wants people to know that COVID-19 vaccines are extremely safe, provide excellent protection and are working well. While breakthrough COVID-19 cases are increasing, they are still minimal compared to rates of infections in unvaccinated individuals. The vaccines are doing their jobs and are preventing severe illness, hospitalization and death for almost everyone.

Here’s what health experts know about breakthrough symptoms of COVID-19, breakthrough cases and when you should seek medical attention if you think you might have COVID-19.

What are the common symptoms of COVID-19?

According to health experts at the U.S. Centers for Disease Control and Prevention (CDC), the following symptoms are most common:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea

What symptoms require emergency medical attention?

  • Trouble breathing
  • Persistent pain or pressure in the chest
  • New confusion
  • Inability to wake or stay awake
  • Pale, gray, or blue-colored skin, lips, or nail beds, depending on skin tone

What are the differences between COVID-19 symptoms and those of the flu?

According to CDC experts, influenza or flu and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. COVID-19 is caused by a new coronavirus called SARS-CoV-2 while the flu is caused by infection with influenza viruses.

COVID-19 spreads more easily than flu and causes more serious illnesses in some people, according to CDC health experts. It also takes longer before people show symptoms of COVID-19 and people can be contagious for longer.

If you are uncertain whether you have a cold, the flu or COVID-19, get tested.

What do experts know so far about breakthrough symptoms of COVID-19?

Breakthrough cases of COVID-19 still are quite rare and relatively new. So, researchers are beginning to learn more about them. In one documented outbreak of breakthrough infections in Provincetown, Mass., researchers found that 79% of the people who tested positive for COVID-19 had symptoms.

The most common breakthrough symptoms included:

  • Cough
  • Headache
  • Sore throat
  • Muscle aches and pains
  • Fever

Some politicians have spoken publicly about getting breakthrough cases of COVID-19 and many have said that they either were asymptomatic or had mild symptoms. U.S. Sen. John Hickenlooper, for instance, recently said he had mild symptoms when he announced that he had a breakthrough case. Here’s what Hickenlooper tweeted:

“I feel good but will isolate per docs instructions. I’m grateful for the vaccine (& the scientists behind it!) for limiting my symptoms. If you haven’t gotten your shot-get it today! And a booster when it’s available too!”

What should you do if you think you have a COVID-19 breakthrough case?

First, get tested. If you test positive for COVID-19 and your symptoms are mild, you should heal at home. Isolate yourself for 10 days so you do not pass along the infection to others.

If you are having any severe symptoms, seek help. You can get care through a virtual visit or you can call your doctor’s office.

For vaccinated people, the good news is that most people are not getting critically ill.

“About 90% of hospitalized people are unvaccinated,” Barron said. “When you look at fully vaccinated individuals who are hospitalized, they tend to be older. The average age of vaccinated people in the hospital tends to be 65 of older or they have an underlying immunological condition, like cancer.”

If you haven’t gotten your COVID-19 vaccine yet, by all means get it.

To stay healthy overall right now, Barron’s advice is consistent:

“Get the COVID-19 vaccine! Get the flu shot as soon as it is available. Wash your hands. Wear a mask.”

About the author

Katie Kerwin McCrimmon is a proud Coloradan. She attended Colorado College thanks to a merit scholarship from the Boettcher Foundation and worked as a park ranger in Rocky Mountain National Park during summers in college.

Katie is a dedicated storyteller who loves getting to know UCHealth patients and providers and sharing their inspiring stories.

Katie spent years working as an award-winning journalist at the Rocky Mountain News and at an online health policy news site before joining UCHealth in 2017.

Katie and her husband, Cyrus — a Pulitzer Prize-winning photographer — have three adult children and love spending time in the Colorado mountains and traveling around the world.