Dear Doctor: Everyone talks about girls getting the HPV vaccine. But what about boys? Isn’t it just as important for boys to be vaccinated as well?

Dear Reader: You’re referring to the vaccination for human papillomavirus, or HPV. And you’re correct that the vaccination is important for both girls and boys. HPV is the most common sexually transmitted infection in the United States, and it can lead to several types of cancer later in life. About 80 million people in the U.S. are currently infected with some type of the virus. About 14 million more, mostly teens and young adults, become infected every year.

HPV refers to a group of more than 200 related viruses. Of these, more than 40 are spread through direct sexual contact. The majority of HPV infections clear up on their own, often in about two years. The rest, however, can linger. They can lead to health problems that range from mild to life-threatening. Some cause genital warts and are considered to be low-risk. Others can cause cancers in different parts of the body. In women, certain types of HPV can cause cancer of the cervix, vulva and vagina. In fact, most cases of cervical cancer are associated with HPV. In men, the viruses can cause penile cancer. They can also lead to anal cancer, and to cancers of the mouth and throat, each of which can occur in either gender. Men can also be carriers of the types of HPV that put women at risk.

The first HPV vaccine won approval from the Food and Drug Administration in 2006. Today, an updated vaccine protects against nine strains of HPV. It has been extensively tested and found to be safe. Side effects can include swelling, pain or bruising at the injection site. Some people report temporary headache, dizziness, fever or nausea. There is no evidence that the vaccine causes any long-term side effects. When administered before an individual becomes sexually active, the vaccine has been found to be highly effective in preventing the infections it targets.

The HPV vaccine is recommended for all children and adults from ages 9 through 26. The CDC recommends a two-dose schedule of the vaccine for children younger than 15. The second dose is given six to 12 months after the first. For teens and young adults who haven’t been vaccinated before the age of 15, three doses administered over six months is recommended. Although use of the HPV vaccine has been approved for people older than 26, it’s important to talk to your health care provider to see whether it will be beneficial.

For anyone on the fence, consider this: HPV infections cause an estimated 35,000 cases of cancer in men and women each year. But since the advent of the vaccine, infections in teen girls that lead to genital warts and most HPV cancers have dropped 86%. Young adult women have seen a decline of 71%. And among vaccinated women, HPV-related precancers linked to cervical cancer have dropped 40%. As the data show, the HPV vaccine saves lives.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I tripped while I was out running a few months ago and got pretty banged up, including a knock to the head. My wife worried about a concussion and wanted me to see a doctor. How do you know if you have a concussion?

Dear Reader: A concussion is a type of brain injury that can occur when a force is powerful enough to cause the head, along with the brain inside of it, to shake quickly back and forth. This can result from the type of direct impact you experienced when you fell during your run. It may also be caused by an indirect force that’s powerful enough to make the head whip back and forth, as can happen during a tackle or when you’re rear-ended in your car at high speed.

Your brain is basically a passenger within your skull. When something causes your head to stop short or suddenly change direction, your brain continues moving. It bounces and twists and bumps into the interior surfaces of the skull. A concussion results in a chemical change within the brain, along with bruises, tears or injury to the soft and fragile tissues. Because it’s not life-threatening, concussion is typically referred to as a mild traumatic brain injury, or TBI. However, the effects can be serious.

When you have a concussion, symptoms may show up right away, or they can develop over a period of hours or days. Immediately after a concussion, a person may appear dazed or bewildered. They may not immediately be aware of what happened, and it’s possible they won’t recall the moments leading up to the injury. Some people become clumsy, and they may have trouble understanding and following directions. Physical symptoms can include headache, feeling nauseated, vomiting, a feeling of pressure within the skull, blurred or double vision, ringing in the ears and problems with balance and coordination. Some people may develop a sensitivity to external stimuli, including light and sound. The person may report feeling slow or groggy or just generally not OK. A brief loss of consciousness immediately after impact is possible.

Someone with a suspected concussion should seek medical care. You’ll be asked for details about the accident, as well as any symptoms. It’s important to also share information about any medications and supplements, as some can increase risk of bleeding. Diagnosis includes a neurological exam that checks vision, hearing, strength, balance and coordination. Cognitive tests are used to evaluate memory, recall and concentration. It’s possible that someone would be asked to stay overnight in a hospital for observation. In some cases, brain imaging tests may be considered.

In 2018, the U.S. Food and Drug Administration approved a blood test to evaluate concussion. It measures levels of two protein biomarkers that the brain releases into the blood within 12 hours of a head injury. It’s not a diagnostic test for concussion, but it does help predict which patients will have injuries that will be visible in a brain scan.

With 3.8 million reported concussions per year, this is a common injury. It’s also a potentially serious one. It’s important, so we’ll say it again: If you suspect a concussion, seek medical care.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Hello again, dear readers, and welcome to part two of our monthly letters column. 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 that 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.

Thank you again for all of your mail. We look forward to seeing you here soon for our regular letters column.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)