Flue cases in Massachusetts started rising around Thanksgiving and increased steadily, with an especially steep climb in the last week of 2017.

Feeling achy and feverish? Your misery has plenty of company.

By the end of December, the tally of flu-like illnesses in the state exceeded the peaks in the two previous seasons, when the biggest number of cases occurred in February and March.

And while it’s unclear whether the annual flu epidemic will be worse this year, or just arrived earlier, fears have been stoked by the severity of the flu in Australia during its most recent season and the fact that the vaccine may protect against the predominant strain of the flu only 30 percent of the time.

Despite the worries, doctors and public health officials say there is no evidence that people are getting sicker than usual.

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 Flu cases in Massachusetts started rising around Thanksgiving and increased steadily, with an especially steep climb in the last week of the year.

“This is a bad flu season but not a horrible one,” said Dr. Andrew G. Villanueva, a lung specialist and chief quality officer at the Lahey Hospital & Medical Center in Burlington.

The flu season, while clearly in full swing, doesn’t “feel different” from previous years, Villanueva said. “We’re not seeing a lot of employees calling out sick with the flu. We’re not seeing a lot of people being hospitalized because of flu,” he said.

Of course, that could change in a heartbeat.

Even this far into the epidemic, there’s no telling what will happen next, said Dr. Alfred DeMaria, medical director of the Bureau of Infectious Disease and Laboratory Sciences at the state Department of Public Health. Cases may continue their upward trajectory, or the epidemic may have already peaked.

“Every October these experts say it’s going to be a bad flu season,” DeMaria said. “They’re just talking off the top of their heads. It’s hard to predict.”

Worries about the flu’s impact this year were inflamed by reports from Australia, which had one of its worst flu seasons ever. But DeMaria said other countries’ experiences are poor predictors of what will happen in the United States.

Another source of concern is the predominant strain of flu circulating this year, H3N2, which produces more severe illness, especially in older people. Also, in Australia, the flu vaccine protected people against H3N2 only 10 percent of the time. DeMaria said that here the vaccine seems to be 30 percent effective against that strain, a little below the 40 to 60 percent effectiveness typical of most years.