Flu can cause immediate complications, including pneumonia, meningitis, and sepsis. Studies over the past decade show that even after the worst of the coughing, fever and aches have passed, people are at increased risk for heart attacks and strokes in the two to four weeks after recovering from flu, said William Schaffner, MD, the medical director of the National Foundation for Infectious Diseases (NFID) and a professor of preventive medicine and infectious diseases at the Vanderbilt University School of Medicine in Nashville, Tennessee. “The virus is even more nasty than you thought,” Dr. Schaffner said. “Flu initiates a whole-body inflammatory reaction. The damage from flu continues even after one recovers from the acute flu illness. … It’s why many people feel wiped out for two weeks or more after they’ve stopped coughing. This lingering inflammation can involve blood vessels, particularly the blood vessels to the heart and the brain.” Moreover, he said, flu in elderly people may precipitate a permanent decline in pre-flu function, increasing the risk of disability. The warning comes on the heels of a particularly bad 2017–18 flu season, which saw a record number of flu deaths among children and produced the highest rate of flu-related hospitalizations among older adults, according to data released from the Centers for Disease Control and Prevention (CDC). An estimated 80,000 Americans died from the flu and flu-related complications last season, including 180 children.

This Year’s Vaccine Expected to Be a Better Match

It’s still too early to know how severe the upcoming flu season may become, experts said. This year’s vaccine is expected to provide improved protection against the predominant flu strains in circulation. The vaccine has been updated to better match the B/Victoria strain, and the A(H3N2) component was updated. The CDC’s Advisory Committee on Immunization Practices also recommended reinstating use of the FluMist vaccine this year. Experts advised against using FluMist during the past two flu seasons because the vaccine’s component targeting the influenza A (H1N1) strain was conferring inadequate protection. But vaccination rates continue to be suboptimal in the United States, Schaffner said. Flu vaccination rates actually declined last season compared with previous years. About 58 percent of children age 6 months to 17 years were vaccinated last season, according to the CDC, well short of the national public health goal of 80 percent. There was a 2.2 percent decline in vaccination rates among children age 6 months through 4 years. However, the vaccination rate in this age group is still the highest of any group (67.8 percent). The rate is lowest among children ages 13 to 17 years (47.4 percent). The slippage in vaccination rates may be due to knowledge that the 2017–18 vaccine was not as protective as in previous years. But, Schaffner said, “There is a great deal of partial protection that the vaccine gives. Even if people get the flu, not getting pneumonia, not having to go to the emergency room, not dying, is really a benefit.” Vaccination varies widely among states and specific groups. According to the CDC, 78.4 percent of healthcare personnel were vaccinated last season, a 15 percent increase compared with the 2010–11 flu season. Healthcare workers in long-term care settings, such as nursing homes, had vaccination rates of only 67.4 percent.

High Risk, Low Vaccination Rates in Pregnant Women

Vaccination among pregnant women remains low, with only about half of women receiving the vaccine, said Laura E. Riley, MD, the Given Foundation professor and chair in the department of obstetrics and gynecology at Weill Cornell Medicine in New York City. Pregnant women are vulnerable because their immune systems are not as robust during pregnancy and because of decreased lung volume. Flu infection in late pregnancy is even more dangerous. Women are more likely to give birth prematurely, be hospitalized, or even die. “Pregnant women who get the flu do very poorly,” Dr. Riley said. “This is a particularly vulnerable population, even though they are totally healthy otherwise.” Women who are vaccinated have a 40 percent lower likelihood of being hospitalized during pregnancy, Riley says. Pregnant women who are vaccinated also pass on some protection against flu to their newborn babies, said Wendy Sue L. Swanson, MD, the chief of digital innovation at Seattle Children’s Hospital.  Children born to immunized mothers have a 72 percent reduction in their rate of flu infection in the first few months of life.

Tips for Avoiding the Flu

Federal health authorities say vaccination remains the best way to reduce the risk of contracting the illness and safeguarding vulnerable populations, such as newborn babies and elderly people. Vaccines are recommended for almost everyone age 6 months and older. It’s particularly important for people with underlying health conditions to receive the vaccination, Schaffner said. Last season, more than 90 percent of adults hospitalized for flu had at least one underlying condition, such as heart disease, lung disease, diabetes, or a metabolic disorders. People with asthma and chronic congestive heart failure are also particularly at risk for complications from flu infection. Among children hospitalized for flu last season, more than half had underlying health conditions, such as asthma, neurological disorders, or obesity. Healthy people who get vaccinated are performing a public service to protect the most vulnerable, said U.S. Surgeon General Jerome M. Adams, MD. “It’s not just about getting the individual vaccinated. It’s about getting everyone around that individual vaccinated” Dr. Adams said. “Getting the flu shot is about community and everyone else around you.” Public health officials recommended several actions to soften this year’s flu season:

Everyone 6 months and older should get an annual flu vaccination.To curb flu spread, get vaccinated by the end of October.Take everyday actions to limit spread of flu by remembering the three C’s: Cover, Contain, and Clean. Cough or sneeze into a tissue or your sleeve. If you’re sick, stay home. Clean surfaces frequently exposed to germs.Take antiviral drugs if your doctor prescribes them. Antivirals need to be provided early after the onset of symptoms.