Influenza — the flu — is more than a bad cold. Seasonal outbreaks mean not only misery but also increased hospital admissions and deaths. The last flu season, from October 2018 until May 2019, caused up to 42.9 million illnesses, up to 647,000 hospitalizations and up to 61,200 deaths, according to preliminary numbers from the Centers for Disease Control and Prevention.

What can we expect this year? Australia’s flu season, which runs ahead of ours (May to October), is often a good predictor. Its onset this year was early and there was a higher-than-average number of cases. The U.S. should prepare for a robust flu season, starting this month.

Anti-flu prescription medicines such as Tamiflu can help once you come down with the flu or as a prophylactic if family members have it. But vaccination is the primary line of defense. The CDC estimates that in six flu seasons starting in 2005-06, flu vaccination prevented almost 14 million cases.

In spite of that, many people resist getting a flu shot or the vaccine nasal spray. Most adults (60 percent) understand that vaccination offers good protection, but only 52 percent said they planned to follow through, according to a survey by the National Foundation for Infectious Diseases. That puts not only individuals but all of society at risk, because a high level of vaccination can create “herd immunity,” a kind of biological barrier to the spread of an infectious disease.

The reasons people don’t get vaccinated are varied. Some find it inconvenient, though flu vaccine can be administered almost anywhere there is a pharmacy. Some don’t like shots, but the nasal spray takes care of that problem. Some who skip the vaccine worry that it will make them sick. They’re wrong: A flu shot or the nasal spray will not and cannot give you the flu.

Although each season’s vaccine is formulated to protect against three of four strains of flu virus, in some years it still isn’t a good match for the strains that actually circulate. But it’s worthwhile to get vaccinated regardless: If you contract the flu, the illness will be less severe and of shorter duration. That could be the difference between missing a week of work and a protracted stay in the hospital.

We can and should be doing more to make flu vaccines more effective. For example, it’s well understood that older adults need more potent vaccines than younger people do because their immune systems don’t work as well. Vaccines with booster “adjuvants” or additional antigen, the substance that elicits immunity, are available for seniors. So far, however, these vaccines are only marginally better at protecting the elderly than the regular formulations. More research on dosage and adjuvants is needed.

There’s also room for improvement in the way we manufacture flu vaccine. Much of each season’s supply is grown in chicken eggs, rather than in “cultured cells” — cells derived from animals and under closely controlled conditions. Chicken-egg vaccine is 70-year-old technology; it’s a slow process and it adds ingredients from the eggs that are known to reduce the vaccine’s effectiveness against some flu strains.

Finally, we are still searching for a “universal” vaccine that will recognize all strains, including newly arising ones, and confer long-term immunity.

The Trump administration is, appropriately, making flu vaccines a high priority. On Sept. 19, the president issued an executive order establishing a task force to spur the modernization of flu vaccine production, support research on a universal vaccine and promote vaccination. A couple of weeks ago, a $130 million National Institutes of Health grant to the Center for Vaccines and Immunology at the University of Georgia garnered headlines: “ ‘Universal’ flu vaccine may be one step closer to reality.”

Flu is bad every year, but it also has the potential to spiral into a pandemic. The flu pandemic in 1918-19, the worst pandemic in history, claimed between 50 million and 100 million lives. It could happen again.

The threat of flu demands an all-out fight for an improved vaccine. Meanwhile, get your flu shot.