Four children who would once have suffered an allergic reaction from consuming a single peanut can now eat a handful each day after taking part in a pioneering medical study.
The children, aged eight to 12, were injected once or twice per month with omalizumab - an antibody used to reduce allergic reactions - for the first 18 weeks of the six-month study by the Hong Kong Sanatorium and Hospital's allergy centre.
From the 12th week of the study, peanuts were gradually introduced into the children's diets. The amount was increased every two weeks, and by the end of the study, the children were eating nine peanuts per day without ill-effects where once they would have suffered rashes, swollen tongues and vomiting from less than one nut.
In controlled tests, children could eat up to 20 nuts without any reaction.
"The result is very encouraging because patients will no longer need to worry about allergic problems from any accidental exposure," said Dr Lee Tak-hong, director of the centre.
Accidental exposure - such as when people with a nut allergy eat food that is not labelled as containing nuts - accounts for about half of the allergic reactions treated by medics. In severe cases, an allergic reaction can cause the victim to stop breathing or lead to a drop in blood pressure that can be fatal.
Unlike other allergies, a peanut allergy rarely disappears and there is no drug to cure it, said June Chan King-chi, senior dietician at the centre.
The centre estimates that about 21,000 Hongkongers suffer from a peanut allergy.
The four patients who took part in the study will continue to eat nine peanuts a day for the next three years to maintain their level of tolerance.
The study was the first of its kind in Hong Kong, and the Happy Valley hospital will now look at carrying out a larger-scale trial. A similar trial in the United States had achieved similar results, Lee said.
The treatment cost some HK$300,000 per patient, Lee said, and was paid for by the hospital.
Tiffany Tsang, 10, was one of the participants. She was found to be allergic not long after she was born, when her parents saw her lips swell after drinking soup containing peanuts.
She said she once had a sore throat and vomited after eating ice cream which contained peanuts. When her younger sister and friends were eating chocolate snacks containing peanuts, she could only watch.
"Now I can have peanut snacks with my sister," she said.