Over 40 people have died so far this year in NSW influenza-related deaths, more than three times the number from 2015.

A more than three-fold increase in influenza-related deaths in NSW has sparked a plea from health authorities for those with the flu to stay away from vulnerable people like the elderly.

So far this year 45 people have died while suffering from flu, which is a big jump from the 13 deaths reported at the same time in 2015.

The jump reflects a huge increase in outbreaks in nursing homes, with 79 reported to date for the year - up from 38 at the same time 12 months ago.

The outbreaks have affected just under 1000 staff and residents.

NSW Health is urging anyone with the flu to stay away from nursing homes, pregnant women and young children, all of whom are susceptible to the highly contagious virus.

Nursing homes are particularly important to avoid, as flu shots are less effective in the elderly.

NSW Health's director of communicable diseases, Vicky Sheppeard, says it's still important for older people to make sure they've had their shots.

"As older people are particularly susceptible to contracting the flu it's important they have the vaccination every year to reduce the risk of hospitalisation and death," Dr Sheppeard said.

She also urges pregnant women to have the flu shot.

"Pregnant women who get influenza are at greater risk of developing serious complications, such as pneumonia, which may result in their hospitalisation," she said.

"Children born to vaccinated mothers also have a reduced risk of contracting influenza in the first six months of life."