“There’s an old saying,” Schaffner says, “which is, ‘If you’ve seen one flu season, you’ve seen one flu season.’ None of us really know what to expect this year, except that we will have a flu season.” Flu seasons can vary in severity from one to the next. The CDC estimates that last year’s flu season was relatively moderate compared with the year before, when the United States had 45 million influenza illnesses, leading to 21 million medical visits, 810,000 hospitalizations, and 61,000 deaths. The CDC notes that the 2019–2020 flu season was unusual in that hospitalization rates among children 0 to 4 years old and adults 18 to 49 years old were much higher than is typical — even higher than during the 2009 H1N1 pandemic. “B strains happen to disproportionately affect young children,” explains Schaffner. It’s anybody’s guess how the 2020–2021 season will proceed, but flu seasons in the northern hemisphere often resemble those that have already swept through the southern hemisphere. “The southern hemisphere serves as a bellwether for the severity of our coming flu season,” says Robert Glatter, MD, an emergency physician with Lenox Hill Hospital in New York City. “At this point in time, we don’t anticipate a severe flu season in the United States based on the fact that the southern hemisphere had a very low number of cases during their flu season, which ended in August.” The authors of a paper published in the CDC’s Morbidity and Mortality Weekly Report in September theorize that lockdowns in Australia, South Africa, and Chile aimed at curbing coronavirus spread may have reduced flu transmission as well. The CDC says that on average, the vaccine reduces the risk of flu by 40 to 60 percent  — and to be clear, the flu inoculation does not protect against COVID-19 and other viruses. The success of the flu vaccine varies every season. A CDC chart shows that the vaccine was 60 percent effective in 2010–2011 but only 19 percent effective in 2014–2015. Why? There are numerous strains of the influenza virus, and the ones that circulate vary from year to year. The CDC and the World Health Organization (WHO) work with the Food and Drug Administration (FDA) to predict which strains will dominate each season, and vaccines typically guard against those strains. When the predictions are accurate, the flu shot is more effective; when the predictions are off, the flu shot is less effective. Despite these uncertainties, there are important reasons to get a flu shot. Consider what it can do: “We’re most concerned about those vulnerable people, but everyone over the age of 6 months should get it,” stresses Schaffner. It’s also fast and easy to get a flu shot. Most are given in a single dose into the arm muscle via needle. Children who are 6 months to 8 years old getting vaccinated for the first time require two doses of vaccine spaced at least four weeks apart. A nasal spray version may be available at some places that offer flu shots, although Dr. Glatter mentions that it was not as effective as the injection in 2019. Not everyone will follow expert advice and get the vaccine this season. On average, here’s how many people across the United States are vaccinated for the flu each year. “In geographic areas with significant numbers of people wearing masks for COVID, it is believed that the intensity of the 2020–2021 flu season should be less severe,” says Glatter. While your best defense against the flu is to get your flu shot every year to help protect against the strains that are most likely to be circulating, you can also take the following steps to help stop viruses from spreading:

Avoid people who are sick — and stay home when you’re sick.Cover your mouth and nose when you sneeze, preferably with a tissue that you then throw away.Wash your hands regularly with soap and water, or use hand sanitizer.Clean areas around you — disinfect surfaces regularly to help remove germs.Keep viruses out — avoid touching your eyes, nose, or mouth with unwashed hands.Focus on overall health — eat nutritious meals, keep hydrated, stay physically active, manage stress, and get good sleep.

The flu might seem like the lesser of two evils, but don’t underestimate it. “The flu can take a normal, healthy person and put them in the emergency room in 48 hours,” says Schaffner. “That’s how powerful it can be.” The good news? The flu can be treated with antiviral medication if caught early. Unlike over-the-counter drugs that temporarily alleviate symptoms, such as congestion, fever, and body aches, prescription antivirals can shorten the duration of the flu by one to two days. These drugs also help reduce the severity of symptoms and prevent serious health complications related to the virus. “But in order to get the maximum effect of this medication,” Schaffner says, “you have to call [your healthcare provider] early.” Antiviral medication is most effective within two days after flu symptoms strike. It can still be beneficial outside that window, though, especially if you’re already at increased risk of flu complications.