Mozambique-Poliomyelitis-Circulating Vaccine-Derived Poliovirus type 2

De Faakto Outbreak Intelligence

26 January 2019

World Health Organization is reporting,

Circulating vaccine-derived poliovirus type 2 – Mozambique

  • 17 January 2019, two genetically-linked circulating vaccine-derived poliovirus type 2 (cVDPV2) isolates were reported from Molumbo district, Zambezia province, Mozambique
  • The first one, was from an acute flaccid paralysis (AFP) case with onset of paralysis on 21 October 2018, a six-year old girl with no history of vaccination
  • The second isolate was from a community contact of the first case, a child aged one-year old


WHO risk Assessment

  • WHO assessed the overall public health risk at the national level to be high due to a decline in population immunity to type 2 poliovirus and the risk of international spread to be medium due to ongoing population movements
  • The detection of cVDPV2 underscores the importance of maintaining high routine vaccination coverage everywhere to minimize the risk and consequences of any poliovirus circulation and underscores the risk posed by any medium to low-level transmission of the virus


WHO Travel Advice

  • WHO’s International Travel and Health recommends that before travelling to areas with active poliovirus transmission, travellers from polio-free countries should ensure that they have completed the age-appropriate polio vaccination series, according to their respective national immunization schedule

(This is the minimium vaccination recommendation-travelers staying longer term in in areas of active polio-virus transmission should review in detail long term vaccination recommendations)



About Polio

  • There is no cure for polio, it can only be prevented. Polio vaccine, given multiple times, can protect a child for life
  • Polio is a highly infectious disease caused by a virus. It invades the nervous system, and can cause total paralysis in a matter of hours. The virus is transmitted by person-to-person spread mainly through the faecal-oral route or, less frequently, by a common vehicle (for example, contaminated water or food) and multiplies in the intestine. Initial symptoms are fever, fatigue, headache, vomiting, stiffness of the neck and pain in the limbs. 1 in 200 infections leads to irreversible paralysis (usually in the legs). Among those paralysed, 5% to 10% die when their breathing muscles become immobilized. (WHO)


    A: Oral polio vaccine (OPV) contains an attenuated (weakened) vaccine-virus, activating an immune response in the body. When a child is immunized with OPV, the weakened vaccine-virus replicates in the intestine for a limited period, thereby developing immunity by building up antibodies. During this time, the vaccine-virus is also excreted. In areas of inadequate sanitation, this excreted vaccine-virus can spread in the immediate community (and this can offer protection to other children through ‘passive’ immunization), before eventually dying out
  • On rare occasions, if a population is seriously under-immunized, an excreted vaccine-virus can continue to circulate
  • WHO’s International Travel and Health recommends that all travelers to polio-affected areas be fully vaccinated against polio



  • There are six different vaccines to stop polio transmission:
  • Inactivated polio vaccine (IPV) – protects against poliovirus types 1, 2, and 3
  • Trivalent oral polio vaccine (tOPV) – protects against poliovirus types 1, 2, and 3 – following the “OPV Switch” in
  • April 2016, tOPV is no longer in use
  • Bivalent oral polio vaccine (bOPV) – protects against poliovirus types 1, and 3
  • Monovalent oral polio vaccines (mOPV1, mOPV2 and mOPV3) – protect against each individual type of poliovirus, respectively