Cancer and its treatments rob the immune system of power, so it’s imperative that patients get the flu vaccine to stave off illness.
Melissa Fouts knows just how serious a bout with influenza — commonly known as the flu — can be for someone with cancer. Early in spring 2019, the 53-year-old was in treatment at The University of Texas MD Anderson Cancer Center in Houston after a recurrence of triple-negative breast cancer.
She was receiving the chemotherapy drug Halaven (eribulin), and her oncologist warned her about a common side effect called neutropenia, a lowered white blood cell count that hinders the ability to fight infections.
That meant trouble for Fouts. The Houston resident’s weakened immune system was no match for the influenza virus. When she developed body aches and a fever, she followed her oncology team’s fever protocol, heading to an urgent care center when her temperature rose above 100.2 degrees Fahrenheit. The results of a flu test came back positive, and she was sent to the emergency department at MD Anderson.
“When you’re being treated for cancer, an infection is concerning,” Fouts says. “Your cancer may be stable, but an infection could ultimately kill you.”
In the emergency department, she was given Tamiflu (oseltamivir phosphate), an antiviral drug that helps treat and prevent influenza, and was sent home for some serious bed rest.
“I ran a high fever for multiple days and slept the majority of the time,” she says. “I was scared that I wouldn’t be able to bounce back.”
THE VALUE OF VACCINATION
Anyone can get the flu, which is a contagious respiratory virus. According to the Centers for Disease Control and Prevention (CDC), it has caused from 9 million to 45 million illnesses, 140,000 to 810,000 hospitalizations and 12,000 to 61,000 deaths in the U.S. each year since 2010. Flu season typically occurs between the beginning of fall and the end of spring.
Among those most at risk of developing the flu are very young children and elderly individuals, as well as patients with cancer, whose immune systems can be compromised by the disease and by chemotherapy, radiotherapy and surgery, according to Dr. Roy Chemaly, professor of medicine in the department of infectious diseases, infection control and employee health at MD Anderson. Targeted drugs, steroids and immunosuppressive therapies such as the mTOR inhibitors used in kidney cancer are also associated with reduced immunity, as are particular cancer types, primarily blood cancers such as leukemia and lymphoma.
A compromised immune system puts people at a particular disadvantage when it comes to fighting off the flu, because they are unlikely to have built up any immunity to the virus.
Although people tend to develop immunity to a strain of flu they’ve had, they are likely to come in contact with other strains, possibly several, in any given year. “We’re vulnerable to flu because we don’t mount enough immunity, because there are different influenza strains every year,” Chemaly says. “Natural immunity isn’t there.”
That’s why getting a flu shot offers one of the best ways to prevent the illness. According to the CDC, when avail- able flu vaccines are well matched to the strains of flu circulating in the community, the flu shot can be 40%-60% effective in the overall population.
Particularly at risk of developing the flu are people with hematologic cancers like leukemia and lymphoma or those who have had stem cell transplant, according to Chemaly. “That’s because of both the treatment and the cancer itself,” he says. “People with leukemia or multiple myeloma often don’t have a good immune response because of their cancer.” As a result, they are less likely to be protected by the flu vaccine.
In research published in the October 2019 issue of Journal of Clinical Oncology, Dr. Jeffrey Kwong, a scientist with the Toronto-based research institute ICES, and colleagues looked at adults who previously received cancer diagnoses and were tested for flu during the virus’ 2010- 2011 and 2015-2016 seasons in Ontario.
The researchers found that, overall, vaccination was associated with a 21% reduction in laboratory-confirmed flu infections and a 20% reduction in influenza hospitalizations. They found that among patients with solid-tumor cancers, receiving chemotherapy at the time of vaccination had no significant impact on the vaccine’s effectiveness.
However, the researchers determined that the effectiveness of the flu shot was decreased for patients with blood cancers (it was 25% for those with solid tumors versus 8% for those with blood cancers).
Nevertheless, the authors recommended that all patients with cancer get flu vaccinations. “As a society, we have this expectation that vaccines should be 100% effective,” Kwong says, “and flu vaccines sometimes get a bad reputation.
But think about it in the context of medications: Some medications are 20%-30% effective, and we consider them beneficial. With flu vaccines, some benefit and some protection are better than no protection.”
Fouts remains a firm believer in the vaccine, even though she developed the flu in 2019 after getting inoculated against it about six months earlier.
“I’ve gotten a flu shot every year, and prior to last year, it had been 27 years since I’d had the flu,” she points out.
When the shot is successful at preventing the flu, it has the extra benefit of avoiding the complications that can come with the virus, which tend to be worse in those who have cancer than in healthy people.
“People with cancer may get pneumonia or a lower respiratory tract infection,” Chemaly says, adding that they may become oxygen deprived and end up on mechanical ventilation. “If you have any respiratory symptoms, you need to be checked right away.”
Plus, cancer treatment might be put on hold during recovery from the flu. “People with cancer who develop influenza may need to delay chemotherapy, radiation or surgery,” Chemaly says. “Those who are having stem cell transplant may need to delay treatment by a couple of weeks.”
Fouts had to suspend chemotherapy while she had the flu, and then she needed to stop treatment again a few weeks later when she got the human metapneumovirus, which causes upper and lower respiratory disease and led to pneumonia. At that point, she says, her oncologist lowered her Halaven dose in an attempt to strengthen her immune system.
People with weakened immune systems are also vulnerable to developing pneumococcal pneumonia, which can arise with the flu or independently. A pneumococcal shot, which helps protect against illnesses caused by Streptococcus pneumoniae bacteria and can be given at the same time as the flu vaccine, may be recommended for some people with cancer who are immunocompromised.
The CDC keeps tabs on where the flu is occurring, and which viruses are circulating during each year. This surveillance helps guide treatment of the illness and the design of the season’s vaccine.
For the current flu season, there are several formulations of the vaccine. Many use four strains of inactivated flu to inoculate against the virus. Also available: a recombinant vaccine, which uses synthetic versions of four strains of flu, and a nasal spray that employs live but weakened versions of four strains.
The CDC generally recommends all the vaccine types equally, but it’s important for patients with cancer, especially those who have blood cancers or are taking steroids or mTOR inhibitors, to know that they should never take the live version.
This type isn’t recommended for immunosuppressed people or those in active cancer treatment because, for them, it may cause the flu or be less effective than an inactivated vaccine. Indicated for adults age 65 and older are two vaccines that each inoculate against three strains of the flu. One is a high- dose inactivated flu vaccine, which contains four times more antigen (a component that helps build immunity) than a regular flu shot. The other alternative is an inactivated flu shot with adjuvant, an added ingredient that helps boost immune response.
Currently, the high-dose flu vaccine and flu shot with adjuvant are licensed only for people age 65 and older, including those who have cancer. Whether either vaccine better protects immunocompromised people under age 65 is being studied, but there is not yet sufficient data to support routinely using a high-dose flu vaccine in younger patients who are receiving chemotherapy.
Because of the way flu vaccines are manufactured, patients with egg allergies should ask their doctors which vaccine is right for them.
Common side effects from the flu shot are minor and temporary and include soreness or swelling at the injection site, headache, nausea, fever, muscle aches and fainting. Those who take the nasal spray version can experience flu-like symptoms. Research findings are mixed regarding whether taking acetaminophen or ibuprofen a day or two after inoculation reduces the vaccine’s effectiveness.
Severe side effects are rare but include a high fever, behavior changes or a severe allergic reaction, signaled by difficulty breathing, hoarseness or wheezing, hives, swelling around the eyes or lips, paleness, weakness and a fast heartbeat or dizziness. Patients who experience these symptoms should call 911, go to the nearest hospital or contact their doctor.
To protect yourself or someone you love who has cancer, take some precautions. A main one is to encourage all family members and caregivers to get a flu vaccine. “It’s the best way to protect patients,” Chemaly says. “When family members and caregivers are immunized, it decreases the patient’s time at risk and helps break the chain
Fouts has asked her adult children to get flu shots. “I’ve told them that a flu shot not only protects them from the flu, it also protects me,” she says. She also tries to keep her hands clean and limits her exposure to people. “I have hand sanitizer with me at all times, and I try not to touch anything with my hands. In a large crowd, I wear a mask, and I try to avoid people who are ill,” she says.
That can be trickier than it sounds, Kwong says, as illness isn’t always obvious. “It’s a myth that we all know when we have a flu infection,” he says. “We may have a mild case with no symptoms and still be shedding virus.” What’s mild in a healthy person can be dangerous to one with cancer, he adds.
If you have cancer and develop respiratory symptoms, see a doctor ASAP to find out if it’s the flu or another virus. For flu diagnosed within 48 hours of onset of symptoms, early treatment with Tamiflu can help reduce the severity and duration of the illness.
“Even if it’s not flu, it could be RSV (respiratory syncytial virus), which can also cause complications,” Chemaly says. “If you’re having symptoms, call your doctor and get tested for other respiratory viruses.”
Let your doctor know if someone in your family or with whom you’re in contact has a confirmed case of flu. If you’re receiving chemotherapy, your doctor may recommend a seven-day course of Tamiflu as a precaution: “That’s only if flu is confirmed, and that’s on a case-by-case basis,” Chemaly says.
Other precautions include frequent hand-washing with soap and water or using an alcohol-based sanitizer. Be cautious in public gatherings and consider wearing a mask or opting out of the event.
You really have to protect yourself, Fouts adds. “I know I can’t control everything,” she says, “but I try to control the things I can. To a sick person, I don’t know if there is such a thing as a mild case of flu.”