Ask the Doctors: New booster guidelines for adults over 50

Hello again, dear readers, and welcome back to the monthly letters column. Virus-related mail, which once required a column of its own, has slowed down. That means we can once again fold those questions in with the general letters. Speaking of which ... — Recommendations regarding COVID-19 booster shots have caused some confusion, including for a reader from North Carolina. "Do you know if a second booster will be available soon for elderly persons with no severe autoimmune problems?" she asked. "I had the first booster more than five months ago." You are indeed eligible for a second booster. As of March 29, the CDC recommends a second booster for adults over the age of 50 whose previous booster was four or more months ago.

In addition, all adults who had the Johnson & Johnson vaccine and first booster are eligible for a second booster using an mRNA COVID-19 vaccine. Again, the timing is four or more months after the most recent shot.

— On the topic of supplements to deliver omega-3 fatty acids, a reader wondered about dosage. "I've been a vegetarian for 40 years and use flaxseed oil to supplement my intake of omega-3 fatty acids," they wrote. "The FDA recommends a maximum of 3 grams per day, but my flaxseed oil has 8 grams per serving. Is that too much?"

For adults 51 and older, the recommended daily intake of omega-3 fatty acids is 1.1 grams for women and 1.6 grams for men. The reason for the cap of 3 grams per day is that when taken in high doses, omega-3 supplements can cause blood thinning, lead to excessive bleeding and interact with prescription drugs that affect blood clotting. Unless your doctor has recommended the dosage you are now taking, it's a good idea to find a product that meets the recommended guidelines.

— We heard from a reader whose prescription medications frequently change shape and color, which led to a dangerous mix-up. "I recently had a scary episode after mistakenly taking two doses of one blood pressure drug instead of one each of two different drugs, and it made me quite ill," they wrote. "In the 15 years I have taken these drugs, they have come in five different colors and four different shapes. Does the FDA pay attention to the risks of color and shape changes?"

While the FDA oversees the contents of medications, the shapes and colors are chosen by each manufacturer. And due to patent laws, manufacturers of generic versions of brand-name drugs are not allowed to copy appearance of the originals. Because pharmacies sometimes change suppliers, the same generic medication from a new manufacturer can suddenly come in a different color or shape. This can be confusing and, as happened to you, even dangerous. While it's not a perfect answer, some patients find using pill organizers can make things less complicated.

As always, thank you to everyone who took the time to write. Our mailboxes are overflowing, so we'll be adding a bonus letters column in the next few weeks.

Dear Doctors: I was surprised when I had to have a TB test for a new job and was shocked that it came back positive. I have no symptoms, and I feel fine. How do you get it? Could I have infected my family? I never realized that TB is common enough in the United States to automatically have to test for it.

Dear Reader: Tuberculosis, or TB, is a disease caused by a bacterium known as Mycobacterium tuberculosis. When someone with an active infection coughs, sneezes or shouts, they release minute bits of moisture known as "droplet nuclei," which contain the bacterium. These droplets are tiny enough that they can drift on an air current, move throughout a room and remain suspended for several hours. This makes the disease highly infectious. If someone inhales these droplets, the TB bacteria they contain can reach the lungs, a friendly environment in which they can begin to grow. They can also settle in the lymph nodes and cause tuberculosis of the throat.

Symptoms of TB include fever, weight loss, night sweats and a wet cough that may produce bloody phlegm. If an active TB infection goes untreated, the bacterium can travel via the bloodstream and infect other tissues, including the kidneys, spine or brain.

When someone tests positive for TB but has no symptoms, as in your case, this is known as latent TB. It means that while the bacterium is in your body, it is a small amount and not yet making you ill.

Someone with latent TB is not infectious. They cannot pass along the disease. However, in some people, latent

TB will transition to an active infection, which is known as TB disease. This can take up to two or more years. For that reason, anyone with latent TB should undergo treatment with antibiotics to eliminate the bacterium from the body.

Tuberculosis is a serious international health threat. Worldwide, up to 10 million people develop an active TB infection each year, and 1.5 million die.

In the U.S., thanks to vigilant testing and treatment, the disease isn't as prevalent. But this wasn't always the case. At the start of the 20th century, TB was a leading cause of death in the United States. Historical reports from that time place the number at more than 150,000 deaths a year from TB.

Thanks to intensive efforts at detection, treatment and prevention, along with development of the antibiotic streptomycin in 1943, the U.S has been able to turn the tide. According to the Centers for Disease Control and Prevention, the U.S. saw 7,800 active TB infections last year, and about 500 deaths. Keeping these numbers low is the reason that many employers require a TB test.

Unfortunately, despite this remarkable turnaround, significant challenges remain. This includes the rise of drug-resistant strains of the bacterium, which are not affected by isoniazid and rifampin, the primary antibiotics used to fight the disease. All of this makes it important for you to seek immediate medical care for your latent TB infection, and to complete the course of medications exactly as prescribed.

Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.