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Immunity to poliomyelitis in Victorians
Katharine Hogg1, Geoff Hogg, Rosemary Lester
1Murdoch Children's Research Institute, Royal Children's Hospital, Department of Microbiology & Immunology, The University of Melbourne, Victoria.
Australian and New Zealand Journal of Public Health
|November 5, 2002
Summary
Poliomyelitis immunity in Victoria is high, exceeding reported vaccination rates. This suggests the Australian Standard Vaccination Schedule, possibly aided by vaccine strain spread, maintains sufficient herd immunity for eradication efforts.
Area of Science:
- Immunology
- Public Health
- Virology
Background:
- The World Health Organization (WHO) aims for poliomyelitis eradication by 2005.
- Introduction of inactivated poliovirus vaccine (IPV) into the Australian Standard Vaccination Schedule was considered.
- Assessing current poliomyelitis immunity in the Victorian community was crucial.
Purpose of the Study:
- To evaluate the seroprevalence of poliomyelitis antibodies in the Victorian population.
- To determine if existing immunity levels support herd immunity goals.
- To inform decisions regarding Australia's poliomyelitis immunization program.
Main Methods:
- Sera from 1,775 individuals across three Victorian population samples (1990-1995) were analyzed.
- Neutralizing antibody titers against each poliovirus type were measured.
- WHO-recommended procedures were followed for serological testing.
Main Results:
- High seropositivity rates (76-100%) for all poliovirus types were observed in infants and adults under 40.
- Specific seropositivity: Type I (90-100%), Type II (94-100%), Type III (80-97%).
- Reported immunization rates were significantly lower than demonstrated seropositive immunity levels.
Conclusions:
- Poliomyelitis antibody seroprevalence indicates sufficient immunity for herd immunity in Victoria.
- Higher immunity than reported vaccinations suggests a role for vaccine strain poliovirus spread.
- The current vaccination schedule has maintained protective immunity in the absence of wild poliovirus.