With the omicron variant spreading rapidly, the United States is all but certain to see a sharp rise in breakthrough coronavirus infections among vaccinated people. These cases were relatively rare in the pre-omicron days, but the new variant has shown an ability to slip past the body’s first line of immune defenses. That means many Americans who have gotten the shots will at some point test positive.

Coronavirus vaccines act like a shield against disease, not an impenetrable barrier, and they offer protection against the omicron variant. Health authorities say booster shots of the Moderna or Pfizer-BioNTech vaccine are the best defense against serious illness, providing robust protection against severe disease. Your likelihood of developing a breakthrough infection is lowest if you’ve gotten the additional shot. The initial two-shot vaccine regimen still offers protection, but it’s not as effective against the omicron variant without boosters.

If you do get a breakthrough infection, here’s some advice on how to navigate it.

What to know about the omicron variant of the coronavirus

What should I do if I test positive for the coronavirus?

While some breakthrough cases are asymptomatic, experts say most tend to bring mild to moderate symptoms. A cough, a sore throat, muscle aches and a low fever are common, but keep in mind that breakthrough symptoms don’t always resemble the version of covid-19 unvaccinated people get. Some patients report headaches, nasal congestion and sneezing — signs of illness more typically associated with colds or allergies.

When you’re feeling sick, or when you think you’ve been exposed to the coronavirus, the most important thing you can do from the get-go is to get tested. Laboratory-based polymerase chain reaction tests, or PCR tests, are most accurate, but at-home tests do a good job detecting symptomatic cases, too.

“Even if you think it’s just allergies, it would be best for you to go ahead and get a covid test and make sure you don’t have it before you go to work or school or church, because those symptoms can be very mild,” said S. Wesley Long, medical director of diagnostic microbiology at Houston Methodist hospital.

A positive test, whether done at home, in a doctor’s office or at a testing center, should be taken seriously, said Rob Murphy, an infectious-disease expert at Northwestern University.

Whether you have symptoms or not, you should first contact your health-care provider to determine the next steps. If you tested positive with a rapid test at home, a doctor may order a lab-based test for confirmation. Depending on your medical history, the doctor may recommend at-home care or clinical treatment.

You should also contact family members, friends, colleagues and anyone else you’ve had close contact with and tell them you have the coronavirus.

From there, follow the isolation recommendations from health officials (more on that below).

At-home coronavirus tests: When to take them, how to get them and more

How long should I isolate or quarantine with a breakthrough infection?

If you don’t have any symptoms but have tested positive for the coronavirus, you should isolate from others for 10 full days, beginning the day after you took the test. If you develop symptoms during that time, you must start the clock over, according to guidance from the Centers for Disease Control and Prevention.

If you are symptomatic, start the 10-day period after first developing symptoms, the CDC said.

There’s no doubt it can be tough for some people to isolate, particularly when there are multiple people under one roof. Murphy recommended using a separate bedroom and bathroom if possible and sanitizing high-touch surfaces if you have to share. He also advised wearing a mask and encouraging others in the house to do the same, staying at least six feet from other people and pets and, when weather permits, opening windows for ventilation.

The CDC also recommends avoiding sharing personal items such as dishes, utensils and towels.

While isolation is for people who have been infected, quarantine is for those who have been only exposed and possibly infected. People who have come into close contact with an infected person may need to quarantine. The CDC defines close contact as being within six feet for 15 minutes or more over a 24-hour period.

Those who have not been fully vaccinated should quarantine for a full 14 days after their last exposure to the person with the coronavirus, according to the CDC. Those who are fully vaccinated do not need to quarantine unless they develop symptoms, but they should get tested five to seven days after exposure and wear a mask indoors in public places for two weeks after exposure or until receiving a negative test result, the CDC said.

How omicron is reshaping the pandemic
Omicron is the fifth coronavirus variant of concern and is spreading rapidly around the world. Here’s what we know. (Luis Velarde/The Washington Post)

If others in my household are sick, too, can we be together?

Yes, assuming everyone in the household has contracted the virus, there’s no longer a need to separate from them, experts said.

How can I treat breakthrough covid-19 at home? What supplies should I have on hand?

Many people with breakthrough infections may not need any special care. There’s a good chance your symptoms will clear in a few days. But if you are uncomfortable, some at-home and over-the-counter remedies might help take the edge off.

Sterling N. Ransone, a family physician in Deltaville, Va., and president of the American Academy of Family Physicians, recommends getting a thermometer and a pulse oximeter, the fingertip device that measures oxygen in your blood. These can help you send valuable information to your doctor if your symptoms worsen. “If they can get me those kinds of numbers, I can give them much better advice on what we can do,” Ransone said.

Acetaminophen can help relieve aches and pains, and cold medications with expectorant can loosen up chest congestion. But it’s important to note that these will alleviate symptoms only temporarily — they will not get rid of the virus faster. Consult your doctor before taking them, follow the dosage recommendations on the label, and make sure they don’t interfere with any other medications you might be taking.

Electrolyte fluids such as Gatorade and Pedialyte can ease symptoms and prevent you from becoming dehydrated. It is good to have a few of these in your fridge.

It is also worth keeping extra masks handy. N95s, KN95s and surgical masks are now easy to order online.

Putting together a kit with these items can save you a trip to the store if you do end up getting sick. “We have everything ready, so if we were to start feeling ill we could go home and we’ve already preplanned,” Ransone said. “We don’t risk exposing our friends and neighbors.”

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How long will I be contagious?

You are considered contagious during the entire 10-day isolation period. Although it’s unlikely, if symptoms such as a cough or fever persist past that point you may still be contagious, said Murphy, executive director of Northwestern’s Robert J. Havey MD Institute for Global Health.

“With these breakthroughs, the whole clinical course is so mild that many of them pretty much recover in a day or two and they’re just waiting to get out of isolation,” he said.

Murphy said it may take a while for a loss of taste and smell to return, but that does not mean you can still spread the virus.

Do I need to test negative before rejoining the community?

No. Once you hit the 10-day mark, you should be fine to commingle again, as long as your symptoms are improving and you’ve gone 24 hours without a fever without using fever-reducing medication. You may still test positive after this point, but health officials say you are not contagious.

Should I ask my doctor about coronavirus therapies?

Yes. If you are vaccinated, you’re probably going to bounce back from a case of covid-19 without medical intervention. But it can’t hurt to ask, especially if you have any conditions that put you at higher risk for severe illness.

That said, our armory of tools for combating covid-19 is changing. The omicron variant has hobbled the use of monoclonal antibodies, laboratory-made molecules that excelled against the other variants. Only one monoclonal antibody treatment, sotrovimab, is expected to work against the omicron variant, and it’s not easy to get.

Other new treatments will become available soon. Federal regulators Wednesday authorized an antiviral drug from Pfizer that appears to reduce the risk of severe illness in high-risk patients when it is administered in the first few days of symptoms. Merck has developed a similar drug that has not yet been authorized.

Overall, experts emphasize that vaccines and booster shots are still the best defense. “If you’re counting on monoclonals instead of getting vaccinated,” said Long, of Houston Methodist, “it’s time to get vaccinated so your body can go and make its own, more effective antibodies.”

What should I do if my symptoms become more serious?

If your symptoms get noticeably worse after a few days, call your doctor. You may need clinical treatment.

Trouble breathing is an immediate cause for concern, said Ransone, the family physician. “If they cough so much they can’t catch their breath, or they’re so short-winded they can’t get a whole sentence out, that’s something that needs to be evaluated in person,” he said.

Other signs of an infection becoming more severe include a temperature moving above 102 degrees, confusion and blue coloration in the face.

If you feel seriously ill and you can’t reach your doctor quickly, head to the nearest emergency room, experts said. Ask a friend or family member to drive you if possible, but note that everyone in the vehicle should be wearing a mask. If nobody is available, don’t take public transportation, which could expose more people — just call 911.

“If you need medical care, you shouldn’t delay,” said Amesh Adalja of the Johns Hopkins Center for Health Security. “Call an ambulance.”