Live oral poliovirus vaccine (OPV) strains can mutate and recombine during replication in the host. Trivalent OPV has long been used to restrain wild-type poliovirus in developing countries. However, recently WHO advocates using monovalent OPV (mOPV) to finally eradicate poliovirus world-wide. We analysed polioviruses recovered from the faeces of 101 elderly patients (divided into three groups by immune status) challenged with mOPV-1 or mOPV-3. A high number of nucleotide mutations was found in the viral capsid-protein-encoding regions. Some of these mutations caused amino acid changes in or near regions with neutralizing epitopes, especially in mOPV-1-derived strains. The quantities of mutations in recovered poliovirus strains correlated with prevaccination immune status (seronegatives have more mutations) and excretion duration. Duration of excretion appears to be the dominant factor for the accumulation of mutations in mOPV-derived strains in vaccinated elderly people.
[Show abstract][Hide abstract] ABSTRACT: In this study, the immunity level of the southern Greek population in the 1-10-year, 11-20-year, 21-30-year and 31-40-year age groups with regard to Sabin vaccine strains and a collection of 11 recombinant and three non-recombinant poliovirus vaccine strains was determined. The results showed the lowest neutralization titre in the 21-30-year-age group against poliovirus type 3. Moreover, the capsid coding region of OPV (oral poliovirus vaccine) derivatives was sequenced in order to identify mutations that might lead to antigenic changes. In Sabin-1 derivatives a tendency of accumulation of mutations was observed in or near antigenic sites while in Sabin-2 and Sabin-3 derivatives in sites known to be involved in restoring neurovirulence or eliminating their temperature-sensitive phenotype. It was concluded that the combination of mutations in the capsid coding region and not the number of specific mutations in antigenic sites determines the antigenic properties of OPV derivatives and their reactivity with human sera.
[Show abstract][Hide abstract] ABSTRACT: Despite launching the polio eradication initiative in 1995, India is among the world's largest reservoir of wild poliovirus with 559 cases of poliomyelitis reported in 2008. This continued failure has been criticised for its negative impact on routine healthcare delivery. We assessed the impact of the pulse polio immunization programme at the primary health level in terms of services, time and cost.
All activities during a single round of intensified pulse polio immunization were modelled on actual requirements at the primary health centre at Dayalpur in Haryana. Total person-hours and cost per child vaccinated at the primary health centre were computed.
Almost all routine healthcare services at the primary health centre were suspended during the round. Total person-hours consumed were 4446 and the total direct cost was Rs 24.2 per child vaccinated during a single round of the intensified pulse polio immunization programme.
A single round of intensified pulse polio immunization consumes a substantial number of person-hours and leads to a temporary suspension of routine services provided at the primary health centre. This should be factored in while planning any future strategy of polio eradication or control and suggests the need to re-think the 'intensified pulse polio strategy'.
The National medical journal of India 01/2009; 22(1):13-7. · 0.78 Impact Factor
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