Having Covid can be a wildly confusing experience. But you can still make a plan to get through the course of illness.The highly contagious subvariant of Omicron, known as BA.2, has prompted concern among health officials as it becomes the dominant version of the coronavirus around the world. So far, signs suggest that BA.2 is 30 to 80 percent more transmissible than the original version of Omicron, and cases are already going up in several states across the United States.While we have tools to prepare for a spike in cases — vaccination, frequent testing, high-quality masks and social distancing — experts worry that the public’s capacity to keep up with precautionary measures is waning. And it can still be confusing to know what to expect with a Covid infection. When do you need to test? How long will your infection last? Like previous coronavirus variants, BA.2 can be wildly unpredictable in its timeline and range of symptoms.To make matters even trickier, you won’t know for sure if you’re dealing with BA.2 or the original Omicron subvariant. “It’s not something that’s reported clinically,” said Dr. Stuart Ray, an infectious diseases specialist at Johns Hopkins University School of Medicine in Baltimore. But regardless of which subvariant you have, you can apply the same course of action, Dr. Ray said. You should mark your calendar and test at the first sign of illness, track your oxygen levels with a pulse oximeter and be on the lookout for signs that your infection is becoming more serious, like difficulty breathing or chest pains.Early evidence indicates that BA.2 does not make people more sick than the previous version of Omicron, which itself was less severe than the Delta variant. But every patient is different, Dr. Ray said, and while most have mild illness and recover in about a week, it is possible to get really sick from BA.2. Like the original, BA.2 is adept at sneaking past immune defenses, even if you are vaccinated and boosted.Here’s what you need to know at every stage of an infection.When — and how often — to take a Covid-19 testLike the previous Omicron variant, BA.2 moves fast and people who do develop symptoms, may start feeling sick two to three days after an exposure to the coronavirus, said Aubree Gordon, an epidemiologist at the University of Michigan. Some of the early symptoms may be very similar to a cold or flu, and include a sore throat, nasal congestion, cough or fever. Some people also report a loss of taste or smell, muscle aches, headaches, gastrointestinal issues and skin rashes. “I would definitely test as soon as I had any symptoms,” Dr. Gordon said.If you use a home test and get a negative result, you should continue taking precautions and test again 24 to 48 hours later, Dr. Gordon said. It could be that the virus simply hasn’t ramped up to levels detectable on a rapid test yet. If symptoms persist and you still test negative at home a few days later, you may want to get a lab-based P.C.R. test, which is more sensitive at detecting traces of the coronavirus.Even if you’re already vaccinated and boosted, your protective antibodies can wane over time, making you vulnerable to an infection. The Food and Drug Administration has authorized second boosters for older adults and those with underlying medical conditions that put them at high risk for severe disease. And while a recent bout with Omicron may provide some immunity, it is possible to be reinfected with the new version. Testing positive on a rapid antigen test can provide important information about when you’re contagious to others. If you’re at high risk, it’s also critical to test and consult with a doctor early in the course of illness in order to be eligible for antiviral pills or monoclonal antibody therapy, which need to be taken within five days of symptom onset.How long it will take to recoverWhile early Covid-19 symptoms remain pretty similar across different variants, what has changed is the course of illness, according to Dr. Roy Gulick, chief of infectious disease at NewYork-Presbyterian/Weill Cornell Medical Center. Some patients never develop more than mild symptoms, while others see their fever or other symptoms start to improve about five to six days after they first get sick, he said. The period between days 5 and 10 is critical when you have Covid-19 because some people may experience a turn for the worse right around then.“The main reason that people are hospitalized is shortness of breath and low oxygen in the blood,” Dr. Gulick said. If you notice either of these symptoms, especially about a week after you get sick, seek medical care immediately.Fortunately, people infected with Omicron are less likely to need hospitalization than in previous coronavirus waves, Dr. Gulick said. “If someone is hospitalized, we’re seeing that they tend to be hospitalized with milder illness and stay fewer days in the hospital,” he said. “And also the risk of progression while in the hospital is lower compared to previous variants.”That being said, Dr. Gulick reiterated that high risk patients consult with their provider early on after testing positive, before they develop any difficulty breathing, because they may be able to take medications to prevent the progression of symptoms.After a week, a small subset of people might take turn for the worse despite feeling like their symptoms were clearing up. Researchers have found that this second phase of illness is somewhat unique to Covid-19, said Dr. Chaz Langelier, an expert on respiratory infections at the University of California at San Francisco. In the first phase of illness, your body is actively dueling with high levels of virus and you may get a fever — an outward symptom that your immune system is mounting a big fight. People who experience a second phase of Covid-19 no longer have virus in their body, but their immune response has created a domino effect of inflammation in their lungs and the damage may lead to outward signs of extreme fatigue, chest pain, shortness of breath or blue finger tips or lips.The second phase of illness has become less common with Omicron and the BA.2 subvariant, Dr. Langelier said. Because of the immunity from vaccines and boosters, as well as previous infections, most people are able to ramp up an immune response to the virus without wreaking later havoc on the rest of the body. This combination of previous immunity and milder subvariants means that most people should fully recover from their coronavirus infection in two weeks.When it’s safe to go out and be with other peopleIf you don’t have symptoms any more or have been fever-free for 24 hours and other signs of your illness have been consistently improving, the Centers for Disease Control and Prevention says that you can leave isolation after five days. But you should keep wearing a mask around others for an additional five days.The caveat is that this advice is based on older coronavirus variants . And some researchers worry that it may lead to people ending isolation too early. Data from the original Omicron variant suggests that as many as half of Covid-19 patients will still be potentially infectious on day five.Dr. Gordon and other experts recommend “testing out” of your illness to be on the safe side. “Try testing on day five, and if you’re still positive then wait and test at day seven again,” Dr. Gordon said. Rapid home tests correspond pretty well to when your viral load is high and when you’re actually contagious.Once you get a negative rapid test and you meet the C.D.C. criteria of decreasing symptoms, you can consider yourself in the clear, though it may still be a good idea to take it easy when returning to your normal activity levels.