More than 171 million people are fully vaccinated against COVID-19 in the United States, but the highly infectious Delta variant has left some with "breakthrough" cases nonetheless.
These cases were anticipated, because the COVID vaccines weren't designed to eliminate all virus infections, but rather to lower a person's risk of severe illness and hospitalization.
Even now, "being vaccinated gives you a 93% chance of not landing in the hospital with COVID. Those are pretty good odds," said Dr. Luis Ostrosky, chief of infectious diseases at McGovern Medical School at the University of Texas Health Science Center at Houston.
Nevertheless, if you're a vaccinated person who suspects you have a breakthrough infection, you probably have many questions about how to protect those around you and manage your illness.
How sick am I likely to get?
"Most of the people with breakthrough infections seem to have a particularly mild disease, complaining mostly of upper respiratory symptoms like drippy nose, a slight cough," Ostrosky said. "We see a lot of headaches. That's about as much as most people are going to be feeling."
He added that some will also have low-grade fevers or fatigue. All these symptoms can usually be treated with over-the-counter remedies.
A much smaller percentage of people with breakthrough infections will get very sick, said Dr. Aaron Glatt, chief of infectious diseases at Mount Sinai South Nassau in Oceanside, N.Y. The risk of severe illness is higher in people with compromised immune systems or chronic health problems.
"What I tell people is if you have been identified as having had a breakthrough episode you should see your physician, and he or she should help you decide which category you fall into," Glatt said.
What if I've been exposed to someone who tested positive for COVID?
The U.S. Centers for Disease Control and Prevention says vaccinated people exposed to COVID don't have to quarantine unless they develop symptoms. They should wear a mask indoors for 14 days following exposure.
But experts firmly suggest that even vaccinated people get a COVID test, since they could be potentially contagious even if they don't develop any symptoms.
"I think it's reasonable that everybody be evaluated," Glatt said. "If they are vaccinated, they should get tested."
When should I get tested for COVID?
Fully vaccinated people should get tested three to five days after coming into close contact with a COVID-infected person, even if they don't have symptoms, according to the CDC.
Experts also recommend you get tested for COVID if you develop any symptoms related to the infection, even if you're vaccinated.
"Most people are presenting with mild headaches or stuffy nose, so they say, 'It's my allergies.' What I like to tell people is that in COVID times there's no such thing as just allergies -- if you have symptoms, you need to be tested," Ostrosky said.
Glatt agreed, noting that something as minor as sniffles, sore throat or congestion could be a symptom of a breakthrough infection.
"It doesn't have to be a full-blown shortness of breath and cough," he said. "Only a small, small percentage get significant illness."
What should I do if I have a breakthrough infection?
Vaccinated folks infected with COVID should follow the standard isolation procedures set forth by the CDC, staying out of public and away from others for 10 days after symptoms first appear or a test comes up positive.
"They absolutely should not go to work. They're highly contagious," Glatt said. "The fact that you're vaccinated and you have COVID doesn't mean that you're not contagious."
You should also isolate from other people in your household, staying in your room to protect everyone else from your infection.
"The old isolation rules apply exactly the same," Ostrosky said. "Whether you're symptomatic or not, you need to isolate for at least 10 days. After those 10 days, you can go out."
Ostrosky added that immune-compromised people might need to spend up to 20 days in isolation.
If I test positive, should everyone else in my house get tested?
"If you or somebody in your household or in your immediate social sphere tests positive, that should trigger an exposure investigation," Ostrosky said. "All those people should first get quarantined and then tested on day three to five after the exposure."
Anyone who's been in close contact with you should also get tested. The CDC defines "close contact" as having been within 6 feet of a COVID-infected person for a total 15 minutes or more over a 24-hour period.
Who should I tell about my breakthrough infection?
Experts suggest you follow whatever rules are in place at your workplace about reporting your breakthrough infection to your employers.
"We recommend you disclose to your employer so they can take the appropriate workplace actions," Ostrosky said.
You also should think seriously about any places where you might have had close contact with others, and reach out to people you might have infected, Ostrosky and Glatt said.
"If you've exposed people, in my humble opinion you have an ethical responsibility to tell them, 'I exposed you,'" Glatt said.
Do I need to get tested again after my isolation?
You're free and clear after 10 days in isolation, so long as your symptoms are improving and you haven't had a fever for at least 24 hours. You don't have to get retested.
"We no longer recommend routine testing after you test positive. We know that after 10 days the virus, even if you test positive, is not infectious anymore," Ostrosky said.
Could a booster shot help protect me from a breakthrough infection?
The White House has announced that the fully vaccinated can receive a booster shot of the Pfizer and Moderna vaccines eight months after they got their second dose. The program will start the week of Sept. 20, if the CDC and the U.S. Food and Drug Administration give it the green light.
Ostrosky and Glatt both think these boosters could help improve people's ability to fight off a breakthrough infection.
"We're starting to get data primarily from Israel and other countries that have been collecting the data systematically showing that antibodies do decrease gradually over time. We're also starting to find out there's a correlation between antibody levels and protection," Ostrosky said. "The logical conclusion is that as your antibodies wane, it's a good idea to get a booster to boost those antibody levels and protect you."
However, Glatt said there's still much to learn about just what kind of added protection boosters will provide.
"There definitely is a role for boosters, but we're not sure what that role will be for any individual patients at this point other than the highly immunocompromised patients," he said. "I do think that boosters will help us get this under control, to a certain extent."
The U.S. Centers for Disease Control and Prevention has more about COVID-19 quarantine and isolation procedures.
SOURCES: Luis Ostrosky, MD, chief, infectious diseases, McGovern Medical School, University of Texas Health Science Center at Houston; Aaron Glatt, MD, chief, infectious diseases, Mount Sinai South Nassau, Oceanside, N.Y.