Dear Doctors: I had COVID-19, and now I’ve got long COVID. I have neuropathy and brain fog, and when I try to exercise, I get exhausted right away. My doctor said it just takes a while to get back on your feet, like after you’ve had the flu, but this feels different. What is the latest news on long COVID?

Dear Reader: As we enter the fourth year of living with COVID-19, it’s clear the initial illness isn’t the only health risk for those who contract the disease. They also face the chance of developing long COVID, the constellation of symptoms that can continue long after the initial illness has ended.

Symptoms include the physical and neurological effects that you have described. The condition can also adversely affect the heart, respiratory and circulatory systems, stamina, endurance, cognition and mental and emotional health. Long COVID does not appear to be linked to the severity of a case of COVID-19. And to make things even more complex, the symptoms can take a few weeks, or even months, to appear.

The newest data shows that 1 in 5 people who recovered from COVID-19 later develop long COVID. With more than 100 million cases of COVID-19 in the U.S. to date, that puts the number of long COVID patients well into the millions. Because the condition is so new, doctors are still struggling to understand what is happening to their patients. And, as with all new diseases, the learning curve is steep. This puts a burden on both patients seeking help and the medical workers trying to treat them. Here at UCLA, as is occurring in medical centers and hospitals throughout the U.S., long COVID treatment is rapidly emerging as a subspecialty of its own.

When it comes to physical activity, a new study backs up your experience -- that is, long COVID can severely reduce the ability to exercise, no matter the person’s prior level of fitness. It also offers clues into the mechanics of what is happening. Researchers at the University of California, San Francisco analyzed data from studies that compared the exercise performance of about 800 adults who have had COVID-19. Roughly half recovered completely, while the others developed long COVID. While running or cycling, the long COVID group had a diminished ability to use oxygen in the blood to fuel muscles. Additionally, their cardiac function, including heart rate, wasn’t able to meet the needs of the exercise. Why this happens is not yet clear, but each new bit of information suggests new paths forward.

At this time, the guidance for long COVID patients is to take a modulated return to exercise. This can mean adding as little as a few extra steps to a walk or run or a few extra strokes of a swim every few days or weeks. Research shows that pushing yourself can delay progress. Physical therapy is also emerging as an important tool for recovery. Long COVID continues to be the subject of many of the letters we receive. We’re keeping an eye on new developments and will continue to share them in future columns.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I am 75 years old, and two years ago, I was diagnosed with bullous pemphigoid. I understand this is an autoimmune problem. I also understand that this is more common in older people. I would like to know more about it. I have been prescribed minocycline, which has been helping.

Dear Reader: You are correct that bullous pemphigoid is an autoimmune disorder. That’s a condition in which certain cells in the immune system mistakenly identify the body’s own tissues as a threat. This causes them to go on the attack, which damages and destroys the tissues that they target. In the case of bullous pemphigoid, the immune system attacks the proteins that act as the glue between the two main layers of the skin. These are the epidermis, which is the outer layer of skin, and the dermis, the lower layer of skin that houses blood vessels, sweat and oil glands, nerves, hair follicles, connective tissue and other structures.

The initial symptom of bullous pemphigoid is often an itchy rash, which typically appears on the torso or the limbs. The inflammation that arises due to the immune cells’ rogue activity causes the skin to turn red. The areas of rash also become raised and swollen, as happens when someone has hives. In some cases, as bullous pemphigoid progresses, watery blisters begin to form on the surface of the skin. These can be numerous and can grow quite large. In some cases, they may contain blood. It’s possible for the condition to affect the mucous membranes, including those in the eyes, mouth, esophagus and genitals, but this is rare.

The causes of bullous pemphigoid, which typically develops at age 70 and older, are not fully understood. There is evidence that in some people, it may be triggered by medications. These include certain diuretics, antibiotics, blood pressure drugs and nonsteroidal anti-inflammatories. Again, the reasons for this response by the immune system are not yet known, but a genetic predisposition is suspected to play a role. The condition is somewhat rare, but cases have recently begun to increase. This may be due to the growing population of older adults who, with a wide range of health conditions, are exposed to numerous drugs. It may also be that growing awareness of the condition has led to an increase in diagnoses.

The goal of treatment is to limit the development of new lesions, promote skin healing, manage symptoms and prevent complications. Treatment plans are tailored to each patient’s specific case of bullous pemphigoid. They take into account the individual’s general health, as well as any preexisting conditions. Medications include systemic or topical steroids to manage inflammation and itching, antibiotics for infection and immunosuppressive drugs to calm the immune response.

Minocycline, which you are finding helpful, is an antibiotic used for bacterial infections. Episodes of bullous pemphigoid are often cyclic. They develop, peak, gradually recede and then return. The data shows that with treatment, the disease can go into remission. For about half of patients, this occurs after about two years. To remain in remission, continued treatment may be necessary.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I’ve been reading that it’s a pretty bad flu season this year, and I’m starting to get worried about getting sick. I haven’t gotten a flu shot yet, but I think it might be too late. Is it still worthwhile to get the vaccine? Is this year’s vaccine effective?

Dear Reader: Thank you for bringing up an important topic. This has indeed been a very active flu season so far. It began in October, which is an earlier start than usual, and it is logging high infection and hospitalization rates.

According to the latest numbers from the Centers for Disease Control and Prevention, the United States has seen at least 13 million cases of influenza thus far this season, with at least 120,000 hospitalizations and more than 7,300 deaths. These are estimates, and epidemiologists expect the final tallies to be even higher.

This brings us to your question about whether it’s too late to get the flu vaccine. The answer is a resounding no, it is not too late. To avoid any possible confusion, we’ll flip the sentence into positive territory: Yes, you should absolutely get the flu vaccine, and as soon as possible.

Being vaccinated significantly lowers the chances of becoming infected with the influenza virus. Recent studies show that flu vaccination reduces the risk of infection by between 40% and 60%. The vaccine also helps to lessen the severity of illness if you should get sick. This includes a lower risk of developing the range of potentially dangerous complications that can come with the flu, such as ear infections, bronchitis and pneumonia.

Because different strains of influenza circulate at different rates each year, the makeup of the annual flu shot changes. This is based on epidemiological data, including which flu viruses are making people sick in the run-up to the upcoming flu season, and the rate at which they are spreading.

But viruses are complex, and their behavior is not always predictable. That’s why the efficacy of the flu vaccine can vary from season to season. This year, we’re happy to report that the flu vaccine is a very good match for the strains that are circulating in the U.S. That translates into robust protection from infection and from severe illness.

It’s important to note that, while we talk about “the” flu vaccine, it is actually available in several variations. Different vaccines are specially formulated for infants and children, adults, older adults, pregnant women and people with certain chronic health conditions. Everyone should get the flu vaccine that is appropriate for their age and their specific health status. Let the health care provider who is giving you the vaccine know if you fall into a special category, or if you suspect that you may.

Flu season in the U.S. typically lasts until late spring, which is more than four months away. Going that long without the added protection that a flu shot offers is taking a medical risk. Please, get the shot.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)