Efficacy of live attenuated vaccines after two doses of intravenous immunoglobulin therapy for Kawasaki disease

Background: It is unclear when live attenuated vaccines (LAV) should be administered to children with Kawasaki disease (KD) who have received a second dose of intravenous immunoglobulin (IVIG) after failing to respond to the initial treatment. The present study aimed to assess the efficacy of LAV after two IVIG treatments and to explore the appropriate timing of vaccination. Methods: The present, single-arm, prospective, interventional study included KD patients who had no medical history of measles, rubella, varicella, mumps or vaccinations against these diseases and received two IVIG treatments at age 6 months or older. The subjects received vaccinations against these diseases for the first time at six or nine months after their IVIG treatment. IgG specific to each virus was measured by EIA at three months after the initial vaccination. If the results were negative, the subjects received a booster vaccination at 12 months after IVIG treatment. The primary outcome was the prevalence of positivity for antibodies after the initial and booster vaccinations. Results: The present study enrolled 11 children, three of whom were vaccinated at six months and eight at nine months after IVIG treatment. One and two subjects who were vaccinated at six months remained negative for measles and rubella antibodies, respectively, but all those vaccinated at nine months were positive. Booster vaccination for measles and rubella led to seroconversion in all patients. At the time of their initial vaccination, all the subjects were negative for mumps antibodies, and about 30% were positive for varicella. Booster vaccinations for mumps and varicella resulted in seroconversion in 82% of the subjects. Conclusion: These findings suggested that six months may be too short an interval after two IVIG treatment before administering measles and rubella vaccines whereas nine months may be adequate. The mumps and varicella vaccines were ineffective at either time point, but a sero-response was obtainable by administering a booster vaccination. Clinical Trial Registration: UMIN-CTR, UMIN000007174, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000008452