For most parents, immunisation is a no-brainer with Singapore's National Immunisation Programme outlining the schedule of vaccines that an infant must get to be protected against common childhood infections.

It gets tricky though when it comes to the optional vaccines such as rotavirus, chickenpox, haemophilus influenzae, flu and streptococcal vaccines as these do not fall under the programme.

The decision on whether to give the children all these vaccines depends on the age of the child and the resources available, said Professor Quak Seng Hock, head and senior consultant paediatrician at the division of paediatric gastroenterology and hepatology, The Children's Medical Institute, National University Hospital.

The optional vaccines can be expensive and parents often weigh risks against benefits in choosing them.

Ms Meena Shetty, a banker with two daughters aged three and six, decided to immunise her second child against chickenpox, after her older daughter caught the disease.

'I didn't realise chickenpox would be so painful to manage. I had a hard time keeping my girl from scratching herself,' she said.

Prof Quak said chickenpox vaccine is quite effective. 'If cost is not a problem, parents should consider giving this vaccine to their children as the disease is quite debilitating and the complications can be very severe,' he said.

He added that other recommended vaccines are for haemophilus influenzaie (flu) and streptococcus (pneumonia) as these affect younger children more severely.

Another disease that can be dangerous is the rotavirus infection. It causes diarrhoea and severe dehydration, and sometimes death.

Even though deaths due to rotavirus are not common in Singapore, rotavirus gastroenteritis affects a significant number of children here. Each year, about 600 children are seen at KK Women's and Children's Hospital and treated for rotavirus-induced dehydration.

There are currently two vaccines available here to prevent rotavirus infections in young children. The vaccine should be given within the first five to six months of life and is not recommended for older children, Prof Quak said.

Parents of those children who have not had this vaccine should not be unduly worried.

'There are effective treatments even if the children contract rotavirus gastroenteritis. The key to this is prevention of dehydration and hospitals here can manage dehydration in children very well,' he said.

Under special circumstances, he would recommend optional vaccines. 'One would consider flu vaccine if the child has some existing lung or heart disease. For example, a child with chronic asthma would need the extra protection against flu,' he said.

Flu vaccine should be considered if children travel to temperate countries in winter, Prof Quak added.

'It is essential to offer extra protection to children whose immune systems are compromised, such as those on cancer treatment and those who have received an organ transplant,' he said.

This article was first published in Mind Your Body, The Straits Times on Apr 23, 2008.