Use Of Oral Polio Vaccine Research Articles

Polio eradication: the OPV paradox.

Routine and mass administration of oral polio vaccine (OPV) since 1961 has prevented many millions of cases of paralytic poliomyelitis. The public health value of this inexpensive and easily administered product has been extraordinary. Progress of the Global Polio Eradication Initiative has further defined the value of OPV as well as its risk through vaccine-associated paralytic poliomyelitis (VAPP) and vaccine-derived polioviruses (VDPV). Although both are rare, once wild poliovirus transmission has been interrupted by OPV, the only poliomyelitis due to poliovirus will be caused by OPV. Poliovirus will be eradicated only when OPV use is discontinued. This paradox provides a major incentive for eventually stopping polio immunization or replacing OPV, but it also introduces complexity into the process of identifying safe and scientifically sound strategies for doing so. The core post eradication immunization issues include the risk/benefits of continued OPV use, the extent of OPV replacement with IPV, possible strategies for discontinuing OPV, and the potential for development and licensure of a safe and effective replacement for OPV. Formulation of an informed post eradication immunization policy requires careful evaluation of polio epidemiology, surveillance capability, vaccine availability, laboratory containment, and the risks posed by the very tool responsible for successful interruption of wild poliovirus transmission.

Vaccine associated paralytic poliomyelitis.

Vaccine Associated Paralytic Poliomyelitis (VAPP), although a known hazard with Oral Polio Vaccine (OPV), has not received adequate attention in India despite increasing use of OPV in repeated rounds of national immunization days. An analysis by National Polio Surveillance Project in 1999 suggested that incidence of VAPP is lower in India compared to that in the developed countries. However a re-analysis of the NPSP data suggests that the incidence in India is likely to be 1 in 1.5-2.0 million doses, which is higher than that reported elsewhere. Since 1999, the number of AFP cases in which the vaccine virus has been isolated, has progressively gone down, despite increasing number of OPV doses being administered in the national program. This contradictory phenomenon is difficult to explain unless either the doses being actually given are much less than those recorded or the vaccine being given is not potent. It is essential that the problem of VAPP is looked at in depth, and if it reveals that it is a significant problem then it would be imperative to gradually replace OPV by IPV in the national program. This article suggests a plan for gradual introduction of IPV in the national program, which will not only eliminate the problem of VAPP but also address other post polio eradication concerns.

Paralytic poliomyelitis caused by a vaccine-derived polio virus in an antibody-deficient Argentinean child

We describe a case of poliomyelitis in a 3-year-old Argentinean boy with X-linked hypogammaglobulinemia. The child had no history of polio vaccination, but a poliovirus isolated from a stool sample had 97.2% genetic similarity to the Sabin 1 vaccine strain. According to the WHO definition, this is the first case reported of a vaccine-derived poliovirus infection recorded in continental Latin America.

Vaccine-associated paralytic poliomyelitis in India during 1999: decreased risk despite massive use of oral polio vaccine.

Vaccine-associated paralytic poliomyelitis (VAPP) is a rare but serious consequence of the administration of oral polio vaccine (OPV). Intensified OPV administration has reduced wild poliovirus transmission in India but VAPP is becoming a matter of concern. We analysed acute flaccid paralysis (AFP) surveillance data in order to estimate the VAPP risk in this country. VAPP was defined as occurring in AFP cases with onset of paralysis in 1999, residual weakness 60 days after onset, and isolation of vaccine-related poliovirus. Recipient VAPP cases were a subset with onset of paralysis between 4 and 40 days after receipt of OPV. A total of 181 AFP cases met the case definition. The following estimates of VAPP risk were made: overall risk, 1 case per 4.1 to 4.6 million OPV doses administered; recipient risk,1 case per 12.2 million; first-dose recipient risk, 1 case per 2.8 million; and subsequent-dose recipient risk, 1 case per 13.9 million. On the basis of data from a highly sensitive surveillance system the estimated VAPP risk in India is evidently lower than that in other countries, notwithstanding the administration of multiple OPV doses to children in mass immunization campaigns.

Epidemiology and the emergence of human immunodeficiency virus and acquired immune deficiency syndrome.

Although acquired immune deficiency syndrome (AIDS) was first described in the USA in 1981, there is evidence that individual cases occurred considerably earlier in Central Africa, and serological and virological data show human immunodeficiency virus (HIV) was present in the Democratic Republic of Congo (DRC) as far back as 1959. It is likely that HIV-1 infection in humans was established from cross-species transmission of simian immunodeficiency virus of chimpanzees, but the circumstances surrounding this zoonotic transfer are uncertain. This presentation will review how causality is established in epidemiology, and review the evidence (a putative ecological association) surrounding the hypothesis that early HIV-1 infections were associated with trials of oral polio vaccine (OPV) in the DRC. From an epidemiological standpoint, the OPV hypothesis is not supported by data and the ecological association proposed between OPV use and early HIV/AIDS cases is unconvincing. It is likely that Africa will continue to dominate global HIV and AIDS epidemiology in the near to medium-term future, and that the epidemic will evolve over many decades unless a preventive vaccine becomes widely available.

Developed countries should not use inactivated polio vaccine for the prevention of poliomyelitis.

Taking into account the global status of polio, it seems evident that the continuing use of oral poliovaccine in all countries is the most obvious and prudent public health policy for the foreseeable future. Possible exceptions might include those countries which are not troubled by the added cost of the inactivated vaccine; whose health services are able to guarantee high levels of vaccine coverage; and which can expect to experience comparatively few importations of wild poliovirus. An important question is whether it is warranted at this time to recommend a combined schedule of inactivated vaccine followed by live vaccine. This implies the addition of at least two inoculations of inactivated vaccine to an already complex vaccination schedule. In most countries, this now includes the administration of three inoculations each of DTP and Haemophilus influenzae as well as one of measles-mumps-rubella vaccine by approximately 12 months of age. Some countries also routinely vaccinate young children against hepatitis B (three additional inoculations). Because most physicians and clinics, as a policy, do not give more than two inoculations at one visit, it implies the need for scheduling additional well-child visits. In the United States, this is a principal factor in the greatly increased estimated costs of such a programme. Experience also shows that as the number of routine visits which are required for vaccination increases, overall vaccination coverage diminishes. The schedule recommended in the United States possesses yet a further problem. Children there would not receive the second dose of oral vaccine until five years of age, thus permitting the accumulation of a large number of preschool children with limited intestinal immunity-a potentially explosive problem were wild virus to be introduced. The inactivated polio vaccine is useful and certainly indicated for the small numbers of persons for whom the live, oral vaccine is contraindicated. However, to use it routinely implies accepting the potential of substantial penalties while reducing but not eliminating, an already extremely small risk of vaccine-associated paralytic illness. From the public health perspective, I therefore argue against the proposition. Copyright 1997 John Wiley & Sons, Ltd.

Non-polio virus interference with oral polio vaccine immunization: possible influence of physical climate and socio-economic status.

In spite of the widespread use of oral polio vaccine (O.P.V.), vaccination programs in many tropical and subtropical countries have apparently failed to provide the expected results in the control of paralytic poliomyelitis (1). Among several factors considered responsible for these unsatisfactory results, an important role has been attributed to the interferences of naturally occurring enteroviral infections on the “take rate” in the intestine, following O.P.V. administration (2,3).KeywordsOral Polio VaccineSubtropical CountryEnteroviral InfectionParalytic PoliomyelitisLive Virus VaccineThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.