BOSTON -- Two years ago, emergency rooms were overwhelmed with influenza patients as hospitals battled one of the longest and most deadly flu seasons in a decade.
But this flu season was virtually nonexistent, public health officials say, with hospitalizations and deaths dropping to their lowest levels in decades.
The state Department of Public Health, which publishes weekly updates on its website, has listed the flu risk as either "minimal" or "low" in Massachusetts every week since September. The agency says infection rates and the severity of influenza are the lowest in the past five years.
Medical experts say measures put in place to prevent spread of the coronavirus -- face coverings, social distancing and restrictions on travel and gatherings -- were major factors behind the drop in flu infections and other respiratory illnesses.
"We know that influenza is transmitted from person to person through close contact, coughing and sneezing of respiratory droplets," said Dr. David Hamer, an infectious disease expert and professor at Boston University's School of Public Health and School of Medicine. "So wearing masks, in particular, but also personal hygiene, surface cleaning, reducing density at work, school, public transit -- all reduce the risk of transmission."
The milder flu season also helped ease the burden on the state's health care system as it battled the COVID-19 pandemic, which has sickened about 587,000 people in Massachusetts and killed nearly 17,000 since the outbreak began last year.
Health officials say increased flu vaccinations could also be a factor in the low numbers of infections and hospitalizations.
Massachusetts and other states took steps to brace for a "twin-demic" of influenza and COVID-19 this winter.
In August, Gov. Charlie Baker imposed a new rule that school-age children be vaccinated for influenza. The state dropped that mandate in January, citing the mild flu season and need to focus on battling the coronavirus.
Massachusetts, like most states, requires public school students to be vaccinated for measles, mumps, rubella and other infectious diseases.
While this flu season was nonexistent, the 2018-19 season was one of the longest and most deadly in years. More than 38 million Americans were sickened, and there were an estimated 405,000 hospitalizations and 22,000 flu-related deaths nationwide, according to the U.S. Centers for Disease Control and Prevention.
The CDC's weekly updates, which also describe the flu risk as "minimal," also report the lowest number of flu-related infections and hospitalizations in decades.
Nearly 100 children died of flu-related illnesses in the 2018-19 season, but there has only been one reported child death this season, the CDC's data shows.
Influenza is a contagious respiratory illness. It can cause a relatively mild illness in many people but more severe illnesses in others. Young children and the elderly are most at risk. Symptoms generally include fever, sore throat, body aches and headache.
State health officials continue to recommend an annual flu vaccine for everyone 6 months or older — especially pregnant women, the elderly and children.
The vaccine may not prevent the flu, but the CDC says it can reduce the severity of symptoms and the length of illness.
Despite education campaigns, many people don’t get the flu shot. Nationwide, only about 45% of adults get the shot every year.
Christian M. Wade covers the Massachusetts Statehouse for North of Boston Media Group’s newspapers and websites. Email him at firstname.lastname@example.org