|Year : 2002 | Volume
| Issue : 1 | Page : 56-
How do the vaccine polio viruses replace the wild polio viruses?
Consultant Pediatrician, A-D-7, Devi Marg, Bani Park, Jaipur - 302 016, India
Consultant Pediatrician, A-D-7, Devi Marg, Bani Park, Jaipur - 302 016
|How to cite this article:|
Paul Y. How do the vaccine polio viruses replace the wild polio viruses?.Indian J Med Microbiol 2002;20:56-56
|How to cite this URL:|
Paul Y. How do the vaccine polio viruses replace the wild polio viruses?. Indian J Med Microbiol [serial online] 2002 [cited 2020 Jul 10 ];20:56-56
Available from: http://www.ijmm.org/text.asp?2002/20/1/56/8344
While scanning literature regarding poliovirus vaccine I found some surprising and alarming facts, for example, (1) There is no 'herd immunity' of any clinical significance produced with oral polio vaccine (OPV), (2) New born babies should not be administered OPV soon after birth because of high contents of IgA in colostrum and the lowered pH in the stomach. Despite these published facts, our National Polio Eradication program is based on the premise that 'herd immunity' is produced and also OPV is administered soon after birth on the recommendations of Government of India and Indian Academy of Pediatrics. In addition, sick children are administered OPV during Pulse Polio Immunization campaigns which has resulted in raised number of cases of vaccine associated paralytic poliomyelitis caused by OPV. I am raising the following issues regarding OPV and seek expert opinion from virologists of our country.
Like some of the natural flora of the intestines, the polio viruses do not colonize the intestines. The phenomenon of chronic carrier does not occur with polio viruses. The wild polio viruses may replicate for 4-8 weeks, may cause the disease and then depart from the human gut. In case of immunocompromised individuals the replication and virus shedding may continue for a prolonged period. Same occurs with the vaccine polio viruses. In immunized individuals OPV stimulates pharyngeal as well as intestinal secretory IgA production preventing virus replication at these sites and thus preventing the occurrence of the disease. After 'take' of the virus in OPV, replication of that serotype virus should also be prevented. If after multiple doses, seroconversion for all the three serotypes has occurred, then next OPV doses would be superfluous. When a vaccine is administered during the incubation period, it may not be able to prevent the occurrence of the disease. Pulse polio immunization and mass immunization with OPV are conducted so that wild polio viruses are replaced by vaccine polio viruses to eradicate polio disease.
In the gut, both wild polio viruses as well as vaccine polio viruses replicate, wild polio viruses may cause the disease, while the vaccine polio viruses may induce the immunity. I seek clarification regarding the following:
1. What will be the inter-action between wild polio viruses and vaccine polio viruses, if a child is already infected with polio virus (incubation period) and vaccine polio viruses in the form of OPV are administered?
2. A child has developed paralytic poliomyelitis because of wild polio virus and OPV is administered within 1-7days of the disease?
3. How do vaccine polio viruses replace wild polio viruses in un-immunized individuals?