Jason Watkins has said he hopes his family being “so open” about their grief following the death of their young daughter will encourage others to talk about bereavement while raising awareness about sepsis.

The Crown actor, 60, and his wife, Clara Francis, have opened up about the emotional experience of their daughter Maudie dying suddenly at age two and a half from the condition in a new ITV documentary which airs on Thursday at 9pm.

Jason & Clara: In Memory of Maudie also sees the couple speaking to medical professionals about how to detect sepsis and supporting other families who have lost a loved one.

At a screening for the documentary in London, Watkins told the PA news agency: “It’s celebrating and remembering her. There is the sort of campaigning side of it, the awareness of sepsis and more funding for sepsis awareness and clinical care.

“And then there is the real emotional side of losing a child within society generally, but then we’re sharing our families’ grief and our memories so there are lots of things going on.

“I hope us being so open as a family and a couple will encourage people to talk about bereavement within families, in all generations as well.

“So that perhaps older generations who are less inclined to talk about it, they can be able to extend their love. Because there’s a big thing of sweeping it under the carpet and just getting on with it. I think those days are gone.”

It’s been 11 years since Maudie died, after she developed a chest infection around New Year 2011. She was told she had a bad cold and croup and was dischanged – but later died that night at home. They later discovered it was sepsis.

Sepsis is a life-threatening reaction to an infection which occurs when your immune system overreacts to the ailment and starts to damage your body’s own tissues and organs, according to the NHS.

Although in the early stages, sepsis, flu and chest infections can have similar symptoms, Colin Graham, chief operating officer at Sepsis Research FEAT, said there are five key symptoms to watch out for.

1. High/low temperature

Sepsis can cause a patient to develop a high fever as part of the body’s immune response, although in some cases they’ll develop a low body temperature (hypothermia) instead. “Hypothermia during sepsis is considered very dangerous,” stressed Graham. “There’s more risk of fatality than when a patient develops a fever.”

2. Uncontrolled shivering

Sepsis can cause a drop in body temperature and severe shivering, which is one response to fighting infection, and is the body’s way of trying to increase its temperature.

3. Confusion

Sepsis can cause acute inflammation and swelling, making it difficult to breathe, and leading to a drop in oxygen levels. “Low levels of oxygen in the blood can cause mental confusion and delirium,” said Graham.

4. Passing little urine

As sepsis progresses, blood pressure may become very low, which means not enough blood and oxygen can reach the body’s organs, says Graham. This can cause organ failure, he said, and when kidneys start to fail, it can lead to a drop in urine output.

5. Blotchy or cold arms and legs

During sepsis, the clotting mechanism works overtime. Nutrients can’t get to the tissues in the fingers, hands, arms, toes, feet, and legs and the body’s tissues begin to die, said Graham. At first, the skin may look mottled or blotchy and may appear blueish. In severe cases of sepsis, the areas of dead skin can turn black, and limbs may need to be amputated.

Someone with sepsis might not show all these symptoms at once and may have other symptoms like difficulty breathing and a rapid heartbeat, which may occur because sepsis can make arteries dilate or widen, causing a drop in blood pressure, which means the heart has to work harder to push the blood through at a normal pressure.

On their own, these symptoms can be an indication of other health problems, said Graham, but a combination of two or more of them, becoming progressively worse, means you need to seek urgent medical attention, so call 999 or go to A&E. He stresses that for every hour treatment is delayed, the chance of survival reduces by over 7%.

Jason and Clara: In memory of Maudie air on Thursday March 30 at 9pm on ITV1.