In this issue of the Journal, Kimmel and colleagues1 report the findings of a valuable study of Ohio family physicians’ and pediatricians’ beliefs about and reported practices of poliovirus immunization. The authors, led by Dr Kimmel, the chairman of the Group on Immunization Education of the Society of Teachers of Family Medicine, found that all physicians were aware of the 1997 poliovirus recommendations, but preferential use of oral poliovirus vaccine (OPV) was related to concerns about the cost of inactivate poliovirus vaccine (IPV) and increased number of injections, while use of the sequential schedule was a reaction to concerns about the risks of vaccine-associated paralytic poliomyelitis (VAPP) and liability.
Kimmel and coworkers found that 63% of family physicians administered OPV, while 67% of pediatricians administered the sequential schedule. Family physicians seem to be more concerned with cost than pediatricians and less concerned with litigation risk; these economic findings parallel findings by other researchers.2,3
One of the main reasons that the American Academy of Family Physicians (AAFP) encouraged parent-provider choice (instead of quickly recommending IPV) was the possibility that the number of injections in the sequential sequence could lead to outbreaks of other vaccine-preventable diseases if immunization rates dropped, especially in disadvantaged areas. The higher cost of IPV was another concern. Also, there was discussion of the importance of intestinal immunity, which is better when OPV is in the schedule. Thus in my opinion, the AAFP position was quite reasonable in 1997. However, in mid- and late 1998 when the price of IPV dropped, and when data became available that showed additional injections of IPV did not have an adverse impact on immunization rates even in disadvantaged communities, the AAFP position appropriately changed.
I believe that the poliovirus vaccine series should start with IPV, and that it makessense to move to the all IPV schedule for the year 2000. I offer several reasons. First, exposure to indigenous wild poliovirus in the United States has ceased. This is because of dramatic progress in poliomyelitis prevention; in 1994 the Americas were declared free of indigenous poliomyelitis, with the last case occurring in 1991 in Peru.4,5 There have been no cases of wild poliomyelitis contracted indigenously in the United States since 1979, and widespread circulation of indigenous wild polioviruses ceased in the 1960s.6 Second, OPV has a slight risk of VAPP, which can occur when the oral vaccine virus reverts to a more virulent form. Of the 125 cases of VAPP reported between 1980 and 1994, the affected individuals were: healthy vaccine recipients (49); healthy contacts of vaccine recipients (40); immunodeficient vaccine recipients (23); immunodeficient contacts of vaccine recipients (7); and community-acquired cases (6).7 VAPP was more common after the first dose of OPV in the all oral vaccine series; 40 of the 49 cases in healthy vaccine recipients occurred after the first dose. The overall risk of VAPP from the all oral vaccine series was 1 case per 2.4 million doses of OPV distributed (125 cases for the 303 million doses of OPV distributed in that time period).7 The risk for the first dose is 1 case per 750,000 first doses distributed. VAPP is paralytic; patients suffer, and their lives are often irreversibly altered. I believe that we can no longer justify the all OPV series in the United States, except in special limited circumstances, such as imminent overseas travel involving an infant. Third, IPV not live, cannot cause poliomyelitis, and thus is safe for immunocompromised patients. Fourth, the majority of parents (61%) prefer to have their child undergo more injections rather than face the possibility of VAPP.8 Fifth, the cost of the inactivated and oral vaccines are now equivalent in the private sector, if ord red from the manufacturer directly (although the book price and the public purchase price of IPV are higher). Sixth, data show high acceptance (91%) of an IPV-starting schedule among parents bringing their children to public health vaccine clinics, including those serving inner-city disadvantaged areas, without decreases in immunization rates.9 Seventh, media attention on antivaccine efforts has grown, and VAPP is an issue due to OPV. Eighth, it is easier to administer and store 1 vaccine (IPV) than to explain the choices and stock 2 vaccines.
Kimmel and colleagues and others1-3 have also noted that dissemination of information on immunization protocols differs between the specialties and, other than the annual recommended schedule, pediatricians often hear the details first. Detailed recommendations on poliovirus vaccine appeared in 1997 in Pediatrics10 but American Family Physician printed the information in January 199911 (although editorials and brief reports appeared before the detailed article, which was delayed because of late-breaking research and policy changes).