1. From the Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
2. World Health Organization Papua New Guinea, Port Moresby, Papua New Guinea
3. Health and Global Policy Institute, Tokyo, Japan
4. Immunization Center, Akita Red Cross Hospital, Akita, Japan
5. Division of Infectious Diseases, Department of Pediatrics, Tokyo Metropolitan Children’s Medical Center, Tokyo, Japan.