Intestinal mucosal immunity is unimportant for polio eradication: the failure of oral polio vaccination

Abstract

Aims

To explore if intestinal immunity induced by infection with live viruses in the oral poliovirus vaccine (OPV) is essential, necessary or even helpful in interrupting transmission of wild poliovirus (WPV) for global polio eradication.

Methods

We reviewed the biology of virus-host interactions in WPV infection and its alterations by OPV-induced immunity for direct evidence of the usefulness of intestinal immunity. We also explored indirect evidence by way of the effect of the inactivated poliovirus vaccine (IPV) on the biology and on transmission dynamics of WPV.

Results

Immunity, systemic and intestinal, induced by infection with WPV or vaccine viruses, does not prevent re-infection with WPV or vaccine viruses respectively, when exposed. Such re-infected hosts shed virus in the throat and in faeces and are sources of further transmission. Immunity protects against polio paralysis-hence reinfection always remain asymptommatic and silent.

Conclusion

Vaccine virus-induced intestinal immunity is not necessary for polio eradication. The continued and intensive vaccination efforts using OPV under the assumption of its superiority over IPV have resulted in the well-known undesirable effects, namely vaccine associated paralytic polio and the emergence of de-attenuated circulating vaccine-derived polioviruses, in addition to the delay in completing global WPV eradication.

Keywords:

• Herd effect
• inactivated poliovirus vaccine
• route of transmission
• secretory IgA
• vaccine-derived poliovirus
• wild poliovirus

Author contributions

TJJ conceptualised the draft. DD and NH contributed in the literature review, drafting and reviewing of the draft and editing. All authors had access to the final manuscript and have approved the same.

Disclosure statement

No potential conflict of interest was reported by the author(s).