Tokyo ( CNN ) -- A safety panel convenes in Japan Tuesday to examine whether two vaccines widely used around the world contributed to the deaths of five children in the past month . Japan 's health ministry ordered doctors to stop immunizing infants with the vaccines while authorities investigate Pfizer 's Prevenar vaccine and Sanofi Pasteur 's ActHIB vaccine -- commonly given to infants in the United States and other developed nations . The health ministry said it suspended the vaccines because the children all died within a short period of time ; four died last week and one died in February . Three of the infants had underlying medical conditions , the health ministry said . Authorities are investigating the medical history of one of the children , and the fifth child had no apparent illness at the time of vaccination , according to the ministry . Both companies maintain that their vaccines -- which are aimed at stopping bacteria that can cause meningitis , pneumonia and other serious infections -- are safe . `` Pfizer thoroughly reviews and continually monitors all of its medicines and vaccines , as safety is our top priority , '' Pfizer said in a statement . `` No causal relationship has been established between the events reported in Japan and vaccination to date . We are conducting a thorough evaluation of these cases in cooperation with the relevant regulatory health authorities . '' Sanofi Pasteur said that the company expresses condolences to the families who had lost children , but also said that no causal relationship between the deaths and the ActHIB vaccine had been established . `` We have been and will be providing all data of ActHIB and will fully collaborate with the ministry of health and welfare , '' the company said . Prevenar prevents illnesses caused by pneumococcal bacteria and ActHIB prevents infection with the Haemophilius influenza . Pediatrician Michiko Suwa said Japan 's medical community hopes the suspension is temporary and fears the government is overreacting to the deaths . `` I 'm concerned that this will impact the future of these critical vaccines , '' she said , noting that she has been receiving concerned calls from parents since the government announced the suspension . The World Health Organization has backed the inclusion of Prevenar in national childhood immunization programs , especially in developing nations where infant mortality remains high . Pfizer estimates it has distributed more than 360 million doses of the vaccine , which is available in more than 100 countries around the world and part of the routine childhood immunization schedule in more than 50 countries . In Japan , 2 million doses have been administered . The U.S. Food and Drug administration said it was aware of the suspensions in Japan , but `` physicians assessing vaccine safety at the FDA and CDC have not detected new safety concerns '' related to the vaccines .
Pfizer 's Prevenar and Sanofi Pasteur 's ActHIB are suspended in Japan . Authorities are investigating whether the vaccines played a role in five recent deaths . Both companies maintain that their vaccines are safe . Comment: