Cantacuzino Institute of Bucharest began the production of OPV in , first using the vaccine seed virus received from the Poliomyelitis Research Institute in Moscow and later since , the vaccine seed virus was received directly from Sabin. Beginning in , the trivalent oral vaccine stabilized with magnesium chloride prepared by the Cantacuzino Institute was used for widespread immunization in Romania.
The administration of oral polio vaccine took place in annual national campaigns from Since , Romania has participated for over 15 years with 11 other states on a WHO collaborative study on the risk of VAPP cases and the risk was the highest in this country. The health authorities from Romania decided in to stop the use of existing vaccine stocks prepared with WHO seed viruses received in and to use a new WHO-B virus seed Behring.
This seed virus was to be available in summer but due to problems with preparation and especially control of seed, WHO-B viruses were distributed by the WHO only beginning at the end of Due to this problem, between July and March , vaccination was only with monovalent OPV type 1 with a single dose administered to children aged 6 wk.
During this period, no case of paralytic poliomyelitis was recorded in Romania. The vaccination was resumed with existing vaccine stocks in April-June. The effects of this 2-year disruption were epidemics which occurred during , caused by wild PV type 1 cases and type 2 15 cases.
The epidemic disappeared in the third quarter of The poliomyelitis epidemic in Romania from allowed an important conclusion: the interruption of TOPV vaccination for 2 years was sufficient to build a contingent of children highly susceptible to infection with PV, allowing re-implantation of wild PVs and their active movements, followed by the emergence of a polio epidemic.
In , vaccination campaigns were introduced in spring and fall. The vaccination schedule was designed so that each child should receive 4 doses TOPV in the first 10 years of life; first dose between 2 and 7 mo, second dose between 4 and 9 mo, third dose between mo and a booster at 9 years of life.
From to May , no cases of paralytic poliomyelitis caused by wild PV were recorded. The latest outbreak of wild type 1 PV occurred between November and April The outbreak involved children from a gypsy community who were unvaccinated or inadequately vaccinated. Because of a high rate of vaccine associated paralytic poliomyelitis reported from , beginning in November , an oral vaccine approved by the WHO was imported and replaced the Romanian produced vaccine[ 28 ].
However, a case-control study demonstrated that the cause of elevated risk of vaccine associated paralytic poliomyelitis in Romania was not the PV vaccine manufacturer but the administration of multiple intramuscular injections of antibiotics within 30 d of receipt of OPV, which increased the risk of paralysis by a factor of 2 to 10 fold[ 29 ].
A decrease of the risk of VAPP was obtained by a reduction of parenteral treatment in recipients of OPV and by the change of the administration schedule of oral polio vaccine from 2 campaigns of two rounds, to throughout the year vaccination since April From , a project of the Ministry of Health supported by the Marcel Merieux Foundation demonstrated the feasibility, safety and high immunogenicity of sequential use of enhanced-potency IPV followed by OPV in 1 of the 41 counties in Romania[ 30 ].
In , we studied the circulation and the biodiversity of enteroviruses in a group of children from a minority population with low anti-polio vaccination coverage from the same area where in a VDPV strain was isolated. Evidence of inter-human circulation of Sabin strains was found[ 34 ] but no VDPV strain was isolated.
The surveillance of at risk populations from at risk areas and maintenance of complete vaccine coverage in the population are important objectives in the framework of global polio eradication. With the development and use of vaccines, the complete eradication of poliomyelitis became an objective.
In , the WHO proposed the worldwide poliomyelitis eradication to its member states. The presence of susceptible subgroups with gaps in immunization favors the introduction of wild PV strains in a vaccinated population. The OPV strains have become the main instrument for the wild-type PV eradication program because it induces both a systemic and mucosal immune response.
The advantage of using IPV is that it poses no risk of vaccine-related disease. The disadvantages for the global introduction of IPV are its cost, the intramuscular administration, its inability to produce optimal intestinal immunity and the biocontainment required for its production. In , 23 years after the decision of the WHO to globally eradicate poliomyelitis, the wild PV type 1 and 3 is still endemic in only four countries: Afghanistan, India, Nigeria and Pakistan.
The type 2 wild PV strain has been eradicated globally since , while a type 2 circulating vaccine-derived PV cVDPV has persisted in northern Nigeria since [ 35 ]. In those regions where the virus has been difficult to control, supplementary immunization with monovalent strains of OPV type 1[ 37 ] or type 3[ 38 ], or with new bivalent oral polio vaccine bOPV containing type 1 and type 3 PV has been introduced[ 39 ].
The objectives for are: interrupting wild PV transmission in Asia and Africa; enhancing PV surveillance and outbreak response; and strengthening immunization systems. This episode demonstrated that if a region is polio free, the risk of wild PV importation from endemic regions remains present until polio is globally eradicated. Because most VDPV strains implicated in poliomyelitis outbreaks worldwide are recombinants between OPV strains and non polio enterovirus strains of Human enterovirus species C[ 41 ], increasing the surveillance of co-circulation and evolution of polio and non-polio enteroviruses must be achieved.
Some research programs are initiated by WHO for obtaining an affordable IPV by reduction of the necessary antigen dose by intradermal administration[ 42 , 43 ], by using adjuvants[ 44 ] and by introduction of Sabin strains as seed[ 45 , 46 ]. In the first 5 to 10 years after global cessation of OPV administration, the maintenance of immunity to polio by IPV use must be assured[ 47 ].
National Center for Biotechnology Information , U. Journal List World J Virol v. World J Virol. Published online Aug Anda Baicus. Author information Article notes Copyright and License information Disclaimer. Author contributions: Baicus A solely contributed to this paper. All rights reserved. This article has been cited by other articles in PMC.
Abstract Poliomyelitis is an acute paralytic disease caused by three poliovirus PV serotypes. Keywords: Poliomyelitis, Formalin-inactivated polio vaccine, Oral polio vaccine. IPV The first inactivated polio vaccine IPV was produced by Salk using virus grown on monkey kidney cells and inactivated with formalin.
OPV The development of the attenuated PV vaccine starts with passages of PV strains in rats and mice followed by passages in the cell culture. References 1. Underwood M. Debility of the lower extremities. In: Treatise on the diseases of children. London: J Mathews; Badham J. Paralysis in childhood: four remarkable cases of suddenly induced paralysis in the extremities without any apparent cerebral or cerebrospinal lesion.
London Med Gaz. Heine J. Beobachtungen uber lahmungustande der untern extremitaten und deren behandlung. Stuttgart: FH Kohler; Charcot JM, Joffroy A.
CR Soc Biol Paris ; 1 — Is acute poliomyelitis unusually prevalent this season. Boston Med Surg J. Caverly CS. Yale Med J. Flexner S, Lewis PA. Experimental poliomyelitis in monkeys: active immunization and passive serum protection. Melnick JL. Current status of poliovirus infections. Clin Microbiol Rev. Paul JR. A history of poliomyelitis. It is not known how long people who received IPV will be immune to poliovirus, but they are most likely protected for many years after a complete series of IPV.
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When a living polio virus invades the body, depending upon the amount of the virus and the immunity of the individual, it may or may not cause polio. But it usually does stimulate the production of protective substances or antibodies. Living viruses can be changed into vaccines, which should stimulate the production of' antibodies and never cause illness.
Changing a living virulent virus into a "killed" vaccine requires the addition of a substance which will destroy the sickness-producing effect without blocking the production of protective substances in the vaccinated child. This principle was applied in the development of the Salk vaccine, which is made by the addition of formalin formaldehyde to living polio virus.
Since the Salk vaccine was first proposed, many claims have been made for it, and it has at times been the subject of public controversy. Now, after almost three years of experience, it is possible to look at the record and come to some firm conclusions about it.
In the United States in the-first forty-nine weeks of , 15, cases of polio were reported to the Public Health Service. In over the corresponding period there were almost twice as many cases—28, This sharp decrease took place during the mass polio vaccination program which was begun in April, First young school children and pregnant women, and later older children and young adults, were given one to three injections of polio vaccine.
At the beginning of the polio season in the early summer of , it was estimated by the National Foundation for Infantile Paralysis that thirty million people, mostly children, had received one or more injections of polio vaccine. That estimate had to be based on the enormous number of bottles of vaccine distributed by vaccine manufacturers and not on the number of persons actually vaccinated. At the beginning of the program carefully planned records were kept by Health Departments of all those vaccinated under their auspices.
But when the program was changed to include over-the-counter sales of vaccine to private physicians, such records no longer included all of those vaccinated.
The marked drop in reported polio cases from to might provide final proof of the value of the vaccine if the number of polio cases in each of the previous years had been relatively constant.
As seen in the first diagram, this is not the case. There have been wide swings in the number of polio cases from year to year. Beginning in the s, when reports of polio became fairly reliable, there were a number of years—particularly in the late thirties when there were many fewer cases than in Following this period, there was a rise in the early s, particularly in when 19, cases were reported.
In , for no apparent reason, there was a sharp drop to about 10, cases. After that, there were a number of "high polio years" reaching a peak in with 57, cases, which was followed by a drop-off to about half that number in These fluctuations in the number of cases per year have no known explanation and occur not only in the United States but in many parts of the world.
It is of interest that a sharp drop also occurred in England and Wales in these same two years, and , even though in those countries only , children had received but one or two injections in a program which began in the late spring of It is, therefore, impossible to tell whether the decrease from to in the United States is a result of the polio vaccine program or whether it is just another sharp swing in the usual pattern of the disease. The total number of cases of polio reported each year includes both paralytic and nonparalytic forms of the disease.
When polio occurs without paralysis, it may be difficult to diagnose, particularly in the absence of an epidemic. Nonparalytic polio has to be differentiated from infections due to other viruses, a distinction which medical advances have made possible only during the past few years. When such other virus infections are recognized in epidemic form, as occurred in Iowa in , these cases are properly not included in the total annual figure for polio.
Improvement in diagnosis has tended to decrease the number of reported cases of nonparalytic polio in recent years. This in turn makes comparisons of total cases in recent years with previous years less reliable.
Paralytic cases, however, are easily recognized, and paralysis only rarely occurs in other infectious diseases. Thus the total number of paralyzed cases is more reliable for year-to-year comparison.
When the paralytic cases to December for and are compared, the decrease is much smaller than that of the total cases. There was a drop from 10, paralytic cases in to in , a decrease of about one third, although there is a possible 5 to 10 per cent error here because of incomplete reports. Reliable records on numbers of paralytic cases for the United States are available for only the last two or three years, and they are, therefore, not precisely helpful at this time in interpreting the sharp decrease of this year.
However, the seriousness of the paralytic disease and the reliability of reports on such cases will make this the best index for measuring the effect of polio vaccine in the future.
We are encouraged that in there was only one epidemic in a major American city, Chicago. This Chicago epidemic was accompanied by an increase in polio in surrounding Cook County and northern Illinois, but this, as well as the other state epidemic in , in Louisiana, was definitely smaller than the most serious epidemics of previous years. It is quite possible that polio vaccination completed before the beginning of the polio season had something to do with the smaller size.
In future years, if the most serious epidemics continue to decrease in size, this will also be an important index of the value of the vaccine. On the other hand, the intense polio vaccination campaign begun after the start of the epidemic in Chicago had no effect on the course of that epidemic. As can be seen in the second diagram, the upswings and downswings on the epidemic curve are of the same shape, and balance each other as is usual in this disease.
If the vaccine given after the start of the epidemic had had a real effect on it, there ought to have been a sharp drop in the number of cases, and the downswing of the curve in the diagram would have been a straight line.
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