The Sabin vaccine is an oral, live-attenuated vaccine, whereas the Salk polio vaccine is an intramuscular (injected) inactivated vaccine. Vaccination with a live attenuated vaccine elicits a greater mucosal (duodenal and oropharyngeal) IgA antibody response in comparison to vaccination with inactivated (killed) vaccines.
Synthesis and secretion of localized antibodies is best when mucosal surfaces are directly stimulated by an antigen (in this case, the oral vaccination allows for contact of the antigen with both the oropharynx as well as the duodenum). In addition to the route of administration having a significant effect on immunity after vaccination, it has been shown that when both live-attenuated and inactivated vaccines are applied to a mucosal surface, the live-attenuated vaccine is more effective at inciting a mucosal IgA response. In the case of polio, the oral polio vaccine (OPV) offers improved mucosal IgA and immune protection at the normal site of viral entry, the gastrointestinal tract.
Zimmerman et al. discuss the advantages and disadvantages of vaccination with the OPV versus the inactivated polio vaccine (IPV). OPV carries a small risk of vaccine-associated paralytic poliomyelitis (VAPP) of 1:750,000 with first doses, whereas IPV does not have this risk. Vaccination schedule options include sequential, all IPV, or all OPV schedules. The sequential schedule entails two doses of IPV at 2 and 4 months of age followed by OPV doses at ages 6-18 months and 4-6 years. In contrast, the all IPV or OPV schedules call for only IPV or OPV respectively to be given at these same ages. The all IPV schedule has become the most common and recommended vaccination schedule in the US. The OPV only schedule is not recommended except in special circumstances where injections are not possible or desired by the patient's parents.
Patel et al. discuss global changes to polio vaccination. The World Health Organization has made it a goal to phase out the use of oral polio vaccine completely in the future. They plan to both introduce the IPV vaccine to countries still using OPV-only schedules by the end of 2015 and then subsequently mandate a switch from the trivalent OPV vaccine (containing component types 1, 2, and 3 of poliovirus) to a bivalent vaccine containing only types 1 and 3. The hope is that the initial IPV vaccination will reduce the risk of reintroduction of type 2 poliovirus after it is excluded from the OPV.
Illustration A summarizes the antibody responses to killed versus live-attenuated polio vaccination; note that the live-attenuated vaccine is associated with higher levels of nasal and duodenal IgA. Illustration B classifies the most common vaccinations as either live or killed.
Answer 2: Intramuscular administration of a killed vaccine would lead to lower levels of mucosal IgA in comparison to patients who receive oral live-attenuated vaccines.
Answers 3,4,5: Serum IgA, IgM, and IgG levels would be expected to be affected roughly equally when comparing killed versus live-attenuated vaccines.
Zimmerman RK, Spann SJ. Poliovirus vaccine options. Am Fam Physician. 1999 Jan 1;59(1):113-8, 125-6.
PMID:9917578 (Link to Abstract)
Patel M, Zipursky S, Orenstein W, Garon J, Zaffran M. Polio endgame: the global introduction of inactivated polio vaccine. Expert Rev Vaccines. 2015 Jan 19:1-14.
PMID:25597843 (Link to Abstract)