People with long-term health conditions have been warned to protect themselves from flu this year.
In 2017, about half of those eligible for a free NHS flu vaccination in Wales missed out, and Public Health Wales has warned some health conditions put people at more risk.
They include diabetes, heart, liver and kidney disease.
Flu is spread via droplets, which are sprayed into the air when an infected person coughs or sneezes.
Direct contact with contaminated hands or surfaces can also spread infection.
Stand-up comedian Aled Richards, 47, had a heart attack three years ago and said he wouldn't risk missing out on the vaccination which could save his life.
"I was diagnosed with a heart attack and within a few days I was on the operating table being fitted with a stent.
"It was quite a shock with no real warning signs but I am so grateful for the excellent treatment I received.
"I made the decision to do everything I could to look after my health from then on."
Mr Richards said more than half of the people living in Wales with a long-term health condition did not get their flu jab last year.
"Considering it's free, takes minutes to do and can help protect me from a very harmful disease, I wouldn't risk missing out," he added.
Student Gracie Macauley, 18, who has type 1 diabetes, has had a flu vaccine every year since she was diagnosed aged 12.
"If you have a condition like diabetes, you have enough health problems. Why would you risk making yourself more ill by catching the flu?" she said.
Chief nursing officer for Wales Jean White said: "There is protection available, and an annual flu vaccine is the best way to prevent yourself from catching flu, which can make your condition worse or can lead to other dangerous complications."