The flu continued to surge this week, with a total of 8,298 laboratory-confirmed cases reported so far this year statewide and 384 in Central Massachusetts, according to the state Department of Public Health. In the region, weekly laboratory-confirmed cases nearly doubled to 90, from 56 reported last week.

Researchers at the University of Massachusetts Medical School are working to find ways to better treat the potentially deadly disease, which is one of the top contributing causes of death worldwide.

DPH estimates between 250 and 1,100 Massachusetts residents die annually from complications of influenza, according to spokesman Omar Cabrera. The exact number is difficult to pinpoint because deaths related to influenza are almost always caused by complications.

“Flu has hit hard this season. We’re definitely seeing the impact here in Worcester,” said Dr. Jennifer Wang, associate professor in the Division of Infectious Diseases and Immunology.

Her team’s research involves looking at how the flu virus changes, addressing why it is difficult to target a direct-hit vaccine or find a treatment that remains fully effective.

“Part of what makes it a continuous challenge is it mutates quickly,” Dr. Wang said.

Most human flu viruses can be categorized into two types, A and B.

Influenza A, which includes this year’s predominant strains of H3N2 and H1N1, also known as swine flu, includes eight strands of genetic material that can recombine with flu strains from other species, such as bird flu, to make a brand new strain.

Dr. Wang said, “That’s what leads to pandemics,” such as the swine flu outbreak in 2009. That was the first global pandemic in 40 years, and it is estimated to have killed up to 575,000 worldwide, according to the U.S. Centers for Disease Control and Prevention.

Influenza B does not break down into subtypes or combine with other species, but it is a factor in seasonal flu outbreaks.

“This year, everything’s out there,” Dr. Wang said.

Vaccines are formulated each year based on researchers’ best estimate of what viruses will be most prevalent. They typically include two influenza A and one or two influenza B viruses.

Combining drugs, instead of relying on one drug such as Tamiflu to treat or prevent flu symptoms, could reduce the viruses’ ability to become drug-resistant.

It’s not just a theoretical concern, according to Dr. Wang, who said there have been pockets of resistance to Tamiflu cropping up in the data.

The UMass team is researching potential drug therapies that could more effectively treat the flu, reduce symptoms, boost the immune system and get around the problem of drug resistance.

Another line of exploratory research is into how the flu can trigger autoimmune diseases, such as type 1, or insulin-dependent diabetes, and lupus. Dr. Wang explained that the flu virus may lead the body to respond by creating an excess of interferon, a protein that has been linked to autoimmune disease.

A clinical trial underway at UMass Memorial Medical Center involves injecting plasma with boosted immunity into patients who are hospitalized with severe influenza and comparing results against standard therapy, such as Tamiflu, or injections of plasma that doesn't have boosted immunity.

But preventing the spread of influenza is still the first line of defense.

While the efficacy of the flu vaccine varies year to year, according to Dr. Wang, “That protection on the whole makes an impact.”

People should still get the flu vaccine this year, if they haven’t already, she said. "They can still help in blunting the severity.”

“We’re actively spreading the word that it’s not late to get the vaccine, that people should get the vaccine,” said Dr. Matilde Castiel, Worcester’s commissioner of health and human services.

Worcester Division of Public Health has been sending out flu vaccination messages through schools, social media and other outlets, according to Dr. Castiel.

Vaccinations are provided from 2 to 4 p.m. Tuesdays at the Worcester DPH office, 25 Meade St.

Pharmacies, health care organizations and local senior centers or community groups around the county may also offer flu shots. Locations can be found at https://vaccinefinder.org/.

According to Dr. Castiel, the city reported 414 cases of flu between July 1, 2017, and Feb. 8, nearly four times the 106 cases seen in the same period the previous year.