Asymptomatic carriers can still spread COVID-19

We received so many letters last month that we needed a bit of additional real estate to get to the most popular topics.

• Regarding the novel coronavirus, we have had several questions about asymptomatic carriers. These are people who, although infected with the virus, have no symptoms of COVID-19, the illness it causes. "Can you be infected with the virus and not be sick?" a reader asked. "If you don't have symptoms, can you still get other people sick?" The answer to both questions is yes. Some people can become infected with the novel coronavirus and not experience any symptoms. However, because the virus is replicating within their bodies, they are able to unknowingly transmit it. That's why, as we've discussed here before, it's so important for us all to wear a facial covering while in public. The virus is broadcast via the tiny droplets of moisture we emit whenever we cough, sneeze, laugh and speak. By wearing a mask, a portion of those droplets are blocked, which protects the people around us.

• Speaking of masks, a reader asked about whether a mask protects him as well as those around him. "If you've got your face covered, won't that keep the virus away from you, even a little bit?" he asked. "I'm not a scientist, but it just seems like common sense." The virus, along with the aerosols that carry it, are both so minute that it takes a specially formulated respirator mask to completely block them. These types of masks are in very short supply and are reserved solely for medical settings. Interestingly, a new study from the University of California, San Francisco, suggests that tightly woven cloth face masks may - and the key word here is "may" - offer a small measure of protection to the wearer as well. Until there is more evidence, though, assume that your mask protects others but not yourself. Remain vigilant about social distancing and hand-washing.

• A reader who walks her dog every day wonders if her pet puts her at risk. "I'm careful about what I touch, but my dog is 'barefoot' on the sidewalk and sniffs everything," she wrote. "Can you get the coronavirus from your dog?" The Centers for Disease Control and Prevention has good news for you. And we quote: "Currently, there is no evidence that SARS-CoV-2 can spread to people from the skin or fur of companion animals."

• We offer a thank-you to a reader from California who wrote in regarding a recent column about lumbar spinal stenosis. It's a narrowing of the spinal column in the lower back that results in compression of the nerves. We talked about a minimally invasive surgery that uses a small implanted device to act as a lift, and thus create additional space within the spinal column. Our reader pointed out that this type of surgery is known as "minimally invasive indirect decompression" rather than "minimally invasive lumbar decompression." We appreciate the correction.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.