UPDATE ON VACCINE-DERIVED POLIOVIRUSES WORLDWIDE, JANUARY 2014–MARCH 2015
Excerpt below; full text, with tables, is at http://www.who.int/wer/2011/wer9025.pdf?ua=1
One of the main tools used in polio eradication efforts has been the live, attenuated oral poliovirus vaccine (OPV),2 an inexpensive vaccine easily administered by trained volunteers. Although OPV may require several doses to induce immunity, it provides long-term protection against paralytic poliomyelitis. Through effective use of OPV, the Global Polio Eradication Initiative (GPEI) has brought wild polioviruses to the threshold of eradication. However, rare cases of vaccine-associated paralytic poliomyelitis (VAPP) can occur both among immunologically normal OPV recipients and their contacts and among persons who have primary B-cell immunodeficiencies (PIDs; defects in antibody production).
In addition, circulating vaccine-derived polioviruses (cVDPVs)3 can emerge in areas with low OPV coverage and cause outbreaks of poliomyelitis. Also, immunodeficiency-associated VDPVs (iVDPVs) can replicate for years in some persons with PIDs. This report updates previous surveillance summaries4 and describes VDPVs detected worldwide during January 2014–March 2015.