![]() Maternal pertussis vaccination programme – interference with primary IPV responseĪs part of the maternal pertussis vaccination programme, introduced in 2012, a dose of polio containing vaccine ( dTaP/IPV) is also given in pregnancy. There is significant overlap between the local authorities with the lowest vaccine coverage and where VDPV2 has been detected ( 1,2). Under-vaccinated children can become infected and pass the infection on to others. The high-density population in the areas affected and the number of individuals under-vaccinated in those boroughs suggests that there is significant potential for the VDPV2 to continue to spread. This falls below the WHO target of 95% coverage. Vaccination coverage for the 3-dose primary schedule in one-year olds in London is well below that achieved for the UK on average and uptake of the pre-school booster in 5 year olds is even lower. Further doses of polio containing vaccines are given at the age of 3 years and 4 months as part of the pre-school booster ( dTaP/IPV) and at around 14 years old ( Td/IPV) as part of the teenage booster. Individuals born after 2004 in the UK will have received IPV which provides excellent protection from severe polio but individuals can still become infected and spread polio virus without exhibiting any symptoms.Ĭurrently, hexavalent DTaP/IPV/Hib/HepB vaccine is offered routinely to babies at 8, 12 and 16 weeks of age. ![]() This vaccine provides good protection against polio and also provides high levels of gut immunity. ![]() Individuals born in the UK before 2004 will have been eligible for vaccination with OPV. This has been formally notified to WHO in accordance with international health regulations. UKHSA has been in close contact with WHO and the Global Polio Eradication Initiative ( GPEI) and it has now been formally confirmed that the UK has a ‘circulating’ VDPV2 based on the detection of the same isolate for more than 60 days, and evidence that the virus detected in London is genetically linked to the poliovirus detected in Israel and the US. The pattern is not consistent with virus shedding by one or a few individuals. The level of PV2 found and the high genetic diversity among the PV2 isolates suggests that there is virus transmission in separate networks of individuals in these boroughs and possibly in some of the other surrounding areas. The sampling has also detected virus in lower concentrations and frequency in areas adjacent to the Beckton catchment area to the South (immediately below the Thames) and to the East. Based on this sampling, virus is considered to be present in sub areas of the Beckton plant covering all or parts of the following London boroughs: Barnet, Brent, Camden, Enfield, Hackney, Haringey, Islington and Waltham Forest. The UK Health Security Agency ( UKHSA) is investigating the extent of transmission of the virus across north-east and north-central London. The UK switched from using OPV to inactivated polio vaccine ( IPV) in 2004, the year after poliovirus was declared eradicated in the WHO European region. Recently vaccinated individuals shed the OPV virus in their stool for a few weeks after and this can be detected through the sewage surveillance. It is considered most likely that an individual entered the UK in February 2022 from a country where oral polio vaccine ( OPV) has been used for supplementary immunisation campaigns and outbreak response. VDPVs behave more like wild type virus, can sustain outbreaks and on rare occasions lead to paralytic presentations in unvaccinated individuals. As expected, since February, the virus has evolved and towards the end of May met the criteria of a vaccine-derived poliovirus ( VDPV2) which means that it has re-acquired the mutations that cause paralysis. ![]() The Beckton sewage treatment plant covers a large catchment area with a population close to 4 million across north-east and north-central London. This is unusual activity and analysis has shown that all PV2 isolates identified since then are genetically related to each other. Vaccine-like type-2 poliovirus ( PV2) isolates were found in sewage samples collected from the London Beckton sewage treatment works in February 2022 and have persisted since. The National Institute for Biological Standards and Control ( NIBSC) of the Medicines and Healthcare products Regulatory Agency ( MHRA) conduct routine environmental surveillance for wild type and vaccine-like polio viruses as part of the UK’s commitment to the World Health Organization ( WHO) global polio eradication programme. Background Summary of incident to date – findings and interpretation
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