A newly state-funded vaccine that becomes available for babies today is expected to avoid up to 1200 children's hospital admissions each year and prevent tens of thousands more cases of illness.
The RotaTeq vaccine, given as three doses of oral drops, protects against the intestinal illness rotavirus.
Almost all young children catch the virus. Symptoms range from none at all to serious vomiting and diarrhoea leading to hospital admission to treat dehydration.
The bug is the most common cause of diarrhoea and dehydration in infants and young children and the symptoms can last three to eight days. By the age of 3 years, 90 per cent of New Zealand children will have contracted rotavirus.
The virus spreads easily from person to person, especially on contaminated surfaces.
"During outbreaks in early childhood settings, rotavirus has been isolated from telephone receivers, drinking fountains, water-play tables and toilet handles," the Ministry of Health's Immunisation Handbook says.
The Government from today pays for young children to have three doses of the oral vaccine, at 6 weeks of age, 3 months and 5 months.
RotaTeq contains live virus that has been weakened through vaccine processing.
Dr Nikki Turner, director of the Immunisation Advisory Centre at Auckland University, said it was more than 90 per cent effective in preventing severe rotavirus cases and 70 to 80 per cent effective against less-severe cases.
She said the vaccine had to be given on time. If given too late, the vaccine had an association - although only very rarely - with a twisting of the bowel, a serious condition known as "intussusception".
The Ministry of Health has told vaccination clinics that in catch-up programmes for slightly older babies, the first dose must be given before 15 weeks of age, with minimum dosage intervals of four weeks, and the last dose before 8 months.
Infection with rotavirus does not confer lifelong immunity. People can be infected several times in their life and outbreaks can occur in rest homes.
The Government's medicines buying agency, Pharmac, estimated that RotaTeq would cost $6.3 million a year.
With the addition of RotaTeq to the immunisation schedule, the Government now offers all children vaccines against 10 diseases at no charge.
The Government's target is that 90 per cent of 8-month-olds will have their primary course of immunisation on time by this month and 95 per cent by December.
For the first three months of this year, the target was achieved for 91 per cent of 8-month-olds nationally. In 14 of the 20 health districts, the result was better than 90 per cent.
Sick baby opened couple's eyes to need for preventive course
Rachael Santos and Chris Mulligan went through "16 days of hell" when their firstborn went down with rotavirus.
Dylan, now 4, was about 6 months old at the time and had just started daycare. Many children at the centre were sick with the intestinal infection about the same time.
"He had an awful time of it," said Ms Santos, a health administration worker, of Glen Eden. "He had rotavirus for about 16 days. In that time he lost a whole heap of weight. I had him in the emergency department [at Waitakere Hospital] twice. He wasn't tolerating fluids and he couldn't eat anything.
"It was 16 days of hell."
Dylan vomited for the first few days, and the diarrhoea persisted for two weeks, causing dehydration.
"That was what really made him unwell. We would top him up with fluids and it would be coming straight out the other end."
It was such an awful experience that after their second child, Zachary (now 19 months), was born, the couple had no hesitation in paying for him to have the three doses of rotavirus vaccine. Ms Santos said it was "definitely worth the $240 we spent on it", although it was a lot of money to find "for something that's not necessary, it's just an extra".
Zachary had not fallen ill with rotavirus when other children around him at daycare had had it.
• Can cause diarrhoea, vomiting and fever.
• Symptoms last 3-8 days.
• Affects almost all young children.
• Oral drops in three doses.
• Given at ages 6 weeks, 3 months and 5 months.