Key result
Previous immunisation with either live or killed poliovaccine was associated with reduced rates and shorter periods of excretion, and more rapid reversion of the excreted virus.
Why the study?
Does previous immunisation with inactivated or live vaccine affect the excretion and reversion of oral poliovaccine strains in children?
Observational
Does previous immunisation with inactivated or live vaccine affect the excretion and reversion of oral poliovaccine strains in children?
Previous immunization with polio vaccine reduces the duration and rate of viral excretion and accelerates viral reversion upon subsequent live vaccine administration.
Answers are grounded in this paper and cite their sources.
May guide OPV use in previously vaccinated children; leaves open need for RCTs to confirm transmission effects.
Excretion of live oral poliovaccine and molecular markers of increased virulence in the viruses isolated were examined in children who were either previously immunised with inactivated or live vaccine or were unimmunised. There appeared to be some effect of previous immunisation with either live or killed vaccine at the second dose of live vaccine. Where an effect was seen it took the form of reduced rates of excretion, shorter time periods of excretion and more rapid and complete reversion of the excreted virus. The data are consistent with the view that poliovirus is able to escape the immune pressure in the gut to some extent by improving its general fitness rather than direct evasion of immunity.
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Minor et al. (2004) conducted an observational in Poliovirus excretion. Previous immunisation with inactivated or live poliovaccine vs. Unimmunised was evaluated on Excretion of live oral poliovaccine and molecular markers of increased virulence. Previous immunisation with either live or killed poliovaccine was associated with reduced rates and shorter periods of excretion, and more rapid reversion of the excreted virus.
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