In January, the government announced that vaccines against Covid-19 would be available to children in Hong Kong as young as five years old. Understandably, parents have mixed views on whether to vaccinate children of such a tender age. The take-up of the vaccine in Hong Kong is already generally lower than in other comparable places due to concerns among the population about inoculation. This situation could be further complicated by separating or divorced parents who do not share the same view on vaccination. Where parents are separated or divorced, there will normally be an order for custody, care and control of their children which regulates who has custody of the children and their day-to-day care. “Custody” means the ability to make the major decisions in a child’s life, such as which school the child attends, and health and religious issues. The more common order made by the court is joint custody, which recognises that children benefit from the involvement of both parents and that they should make important decisions on behalf of their children together wherever possible. This means parents with joint custody will have to reach a consensus on vaccination before either of them can take their child to be vaccinated. However, while theoretically, a parent with sole custody is able to make decisions on his or her own, it is a misconception that the parent with sole custody can go ahead and make all important decisions for the child without any reference to the other parent. Although the parent with sole custody may have the ability to execute those decisions, she or he must always consult the other parent, where possible. Should a parent who has been granted sole custody act unilaterally, the parent without custody can make an application to the court to be heard. In practice, if there is a conflict on an issue such as whether to have the child vaccinated, the court has a duty to consider what would be in the best interests of the child. The parents would be well advised to seek medical advice on this before commencing a court action. If the parents cannot agree, it is likely that the family court judge will appoint a single joint expert, which will be an approved doctor, to provide an opinion for the court to consider. The parents can agree on the single joint expert, failing which the court has the power to appoint one. Parents should acknowledge that they both have a right to be heard on medical decisions, but that conflict should be kept to a minimum. In the absence of agreement, generally, decisions regarding medical treatment are left to the doctors. Jocelyn Tsao, partner, and Philippa Hewitt, professional support lawyer, Withersworldwide