Consequently, none of the vaccines usually recommended in the first years of life can be reasonably administered during intensive chemotherapy because they will be partly or totally ineffective and, in the case of live vaccines, possibly dangerous. Protection against vaccine-preventable diseases in this period can only be assured by continuous and careful clinical evaluations and, whenever possible, the prompt treatment of any disease that may occur. However, the situation is very different in the case of cancer patients who have stopped receiving chemotherapy for 3–6 months, because they can be considered not significantly different from

healthy children in immunological terms [1], [16], [17], [25] and [26]. Consequently, after this period, the subjects who have never received any vaccine can be vaccinated according to the schedule usually used for normal children of the same age. In order find more to protect them see more as soon as possible without risks, inactivated or recombinant vaccines can

be administered 3 months after the completion of chemotherapy, whereas live attenuated vaccines (i.e., MMR and varicella vaccines) should not be given for another 3 months. Moreover, at least one dose of Hib and pneumococcal vaccines should be administered regardless of age even though they are not recommended for normal children aged more than 5 years. When epidemiological reasons suggest the need, inactivated or recombinant vaccines can even be administered during the last part of maintenance therapy. However, it is important to remember that

protection against specific infectious agents will not be complete in all such subjects because of their reduced immune function, and so they still require careful clinical monitoring. In any case, potentially the dangerous live vaccines cannot be recommended during this period unless immune recovery has been demonstrated. It is more difficult to define the best solution in the case of children who have started or completed vaccination schedules before the diagnosis of cancer. Theoretically, the best way of deciding whether or not to administer new doses of the different vaccines is to test residual immunity, and then choose whether to administer all of the scheduled doses of a certain vaccine, only a booster, or nothing at all. However, it is not always possible to determine the antibody titre for each vaccine antigen and, in any case, the correlates of protection of some are not clear. Furthermore, low antibody levels do not always indicate a lack of protection [6], [10], [11], [18], [19], [20], [21], [22], [23] and [24]. One possible solution for children who completed the vaccination schedule before the diagnosis of cancer is to administer a booster dose of all of the vaccines, including Hib and pneumococcal vaccines.