Response to. type 2 vaccine-derived polioviruses. prior to global topv withdrawal. Interim Guidelines

Transcription

1 Respnse t type 2 vaccine-derived pliviruses prir t glbal topv withdrawal Interim Guidelines August 2015

2 GPEI peratinal guidance nte August 2015 Summary Prepare fr prmpt actin fr any area r ppulatin at risk f VDPV2 emergence. Frm August 2015 until the topv-bopv switch date, initiate rapid respnse mp-up immunizatin within 14 days f diagnsis fr every reprt f VDPV2 frm clinical r envirnmental surces, withut waiting fr, and regardless f, final classificatin. Plan and cnduct at least 3 topv runds in areas at risk. If cvdpv2 is fund, adapt and expand the respnse further t stp circulatin, in line with the standard perating prcedures fr utbreak respnse, including ne rund with IPV if nt already used fr SIAs in that area. Purpse The purpse f this dcument is t ffer new strategic guidance n the peratinal respnse t islatin f vaccine-derived pliviruses type 2 (VDPV2) frm any surce in the perid leading up t the glbal withdrawal f trivalent ral pli vaccine (topv), anticipated t ccur in April The Glbal Pli Eradicatin Initiative released new Standard Operating Prcedures fr respnding t a plivirus utbreak, including cvdpvs, an apprach endrsed by the Wrld Health Assembly in May Released in July 2015, new Guidelines fr reprting and classifying VDPVs prvide details n the field investigatin required when a new r already circulating VDPV is detected ( This cmpanin paper ffers guidance as t next steps fr an immediate peratinal vaccinatin respnse t any newly detected VDPV2 effective immediately. Cntext With cntinued prgress twards glbal interruptin f wild plivirus transmissin, it is increasingly imprtant t manage the risk assciated with circulating vaccine-derived plivirus (cvdpv) that can cause paralysis. In the last 10 years, almst 500 children were paralyzed by cvdpv, largely type 2. T eliminate this risk f paralysis due t cntinued use f type 2 live ral pli vaccine, the glbally synchrnized withdrawal f (topv) is scheduled in April 2016, referred t as the switch date, at which time bivalent types 1 and 3 ral pli vaccine (bopv) will replace topv use in in all rutine and supplementary pli immunizatin activities. 1 Or alternate date in 2016 r 2017 t be recmmended by SAGE. Respnse t vaccine-derived type 2 plivirus 1 P age

3 GPEI peratinal guidance nte August 2015 One f the key pre-cnditins fr the topv-bopv switch is the interruptin f all persistent transmissin f cvdpv2 (any evidence suggesting circulatin f greater than 6 mnths after the date f first detectin f the cvdpv2 strain). Prir t the switch date, it is therefre critical that all ptential utbreaks f cvdpv be stpped immediately and nt allwed t take hld, i.e. t becme persistent. The timeline n lnger allws fr watching and waiting t find ut if a type 2 vaccine-derived virus strain is circulating r is being excreted by an immune-deficient individual. Furthermre, a recently emerged VDPV is easier t stp befre the virus adapts further fr widespread circulatin. It is therefre necessary t replace the watch and wait apprach with a strategy fr immediate respnse. Ging frward, even while further field investigatins are initiated t classify a VDPV, an immediate vaccinatin respnse is required fr any new appearance f VDPV2, regardless f subsequent classificatin status (ivdpv, cvdpv r avdpv). Cncretely, therefre, as sn as a new VDPV is identified, plans must be initiated fr apprpriate and targeted immunizatin activities, while investigatins leading t VDPV classificatin g n in parallel ( Applicability This guidance applies t any situatin in which VDPV2 is islated frm any child r adult with acute flaccid paralysis, r frm an envirnmental sample, frm August 2015 until withdrawal f the type 2 cmpnent f OPV. Supplementary immunizatin activities t prevent and rapidly eliminate VDPV2 Principally, the main risk factr fr emergence and circulatin f VDPV2 is lw ppulatin immunity t type 2 plivirus. Objective 1 Plan and implement campaigns t prevent emergence f cvdpv2 in high risk areas Based n risk analysis that identified areas at high risk f cvdpv2 emergence, multiple largescale topv SIAs have been planned which must be implemented in advance f topv withdrawal, in line with the glbal calendar fr supplementary immunizatin activities. Objective 2 Early rapid lcal respnse t prevent further circulatin (must nt wait fr VDPV2 classificatin) Whenever any VDPV type 2 is islated, i.e. as sn as ntificatin is received frm the reference labratry, take immediate actin Immediately plan lcal mp up activities with topv t take place within 14 days Implement supplemental immunizatin activities (SIAs) within 14 days as fllws: Plan t implement 3 mp up runds Respnse t vaccine-derived type 2 plivirus 2 P age

4 GPEI peratinal guidance nte August 2015 Ensure an interval f 14 t 28 days between runds Determine the size f target ppulatin and gegraphic scpe based n risk f spread and estimated duratin f criculatin befre detectin Adapt each campaign t imprve cverage and reach missed children, frm results and lessns learned frm the preceding runds Cmplete 3 mp-up runds f topv, even if the circulatin f the VDPV strain is nt cnfirmed. Objective 3 Expand t large-scale supplemental immunizatin activities if cvdpv cnfirmed Cver all areas at risk and any pssible surce f the cvdpv - t stp circulatin quickly in line with the GPEI Standard perating prcedures fr utbreak respnse Ensure vaccinatin f a minimum f 2 millin children Use IPV in cmbinatin with topv n later than the 3 rd rund f mp-up this will bst sercnversin and the mucsal immune respnse t topv If IPV has been used in an SIA in a gegraphic area, it is nt necessary t use it again. Cntinue t implement topv SIAs until three (3) campaigns have been implemented fllwing the mst recent virus islatin, whether frm an AFP case r an envirnmental sample The main message Frm August 2015 until the topv-bopv switch date, be prepared t respnd rapidly t any detectin f a VDPV2 islate frm clinical r envirnmental surces, withut waiting fr VDPV2 classificatin. Adapt and expand the respnse further if it is cnfirmed as a cvdpv, t rapidly stp circulatin. Respnse t vaccine-derived type 2 plivirus 3 P age

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