Child Paralyzed by Vaccine-Derived Polio

By Kim Smiley

There has been amazing progress in the effort to eradicate polio, but recent cases of the disease are a harsh reminder that the work isn’t complete and now isn’t the time to be complacent.  Public health officials are planning three mass vaccination rounds in less than 120 days after a child was recently paralyzed by polio in Mali.  In addition to this case, the World Health Organization (WHO) announced that two children in western Ukraine were also paralyzed by polio.

The last case of polio was detected in Mali in 2011.  A Cause Map, a visual root cause analysis, can be used to analyze how the child contracted polio as well as help in understanding the overall impacts of this case.  The first step in a Cause Map is to fill in an outline with the basic background information, including listing how the issue impacts the different overall goals.  This issue, like most, impacts more than a single goal.  For example, the child being paralyzed is an impact to the patient safety goal, but the potential for an outbreak of polio is an impact to the public safety goal.

Once the impacts to the goals are defined, the Cause Map itself is built by asking “why” questions and including the answers in cause boxes.  The Cause Map visually lays out all the cause-and-effect relationships that contributed to an issue.  So why was the child paralyzed?  The child was infected with vaccine-derived polio because he was exposed to the disease and wasn’t immune to it, likely because he didn’t receive all four of the required doses of vaccine.  Vaccine rates in Guinea, where the child was from, dropped during the Ebola outbreak.

In this region of the world, oral polio vaccine is used and it contains weakened, but live, strains of polio virus.  After being administered oral polio vaccine, a child will excrete live virus for a period of time.  The live virus can replicate in the environment and there is the potential for it to mutate into a more dangerous form of polio, which is what causes vaccine-derived polio.

Cases of vaccine-derived polio are very rare, but are a known risk of using oral polio vaccine.  The injectable vaccine uses dead polio virus that cannot mutate, but there are other important factors that come into play.  The oral polio vaccine is cheaper and is simpler to administer than the injectable vaccine because medical professionals are needed to give injections.

The use of oral vaccines also eliminates the risk of spreading blood borne illnesses.  Because there are no needles involved, there is no risk of needles being shared between patients.  The oral vaccine also provides greater protection for the community as a whole, especially in regions with poor sanitation.  When a child is fully immunized with the oral polio vaccine this ensures immunity in the gut so that the polio virus is not excreted after exposure.  This is not true with the injectable polio vaccine; an immunized child exposed to “wild” polio would not be infected, but may still excrete polio virus after exposure and potentially spread it to others.  One negative of using the oral polio vaccine is that in rare cases (estimated to be about one in about 2.7 million) the weakened polio virus can cause paralysis in a child receiving their first dose of the vaccine.  Concern over paralysis is one of the reasons that developed nations generally use the injectable polio vaccine.

Polio is highly contagious and public health officials are planning an aggressive vaccine campaign to reduce the risk of an outbreak now that a case of polio has been verified in Mali. The plan is to have three mass vaccination rounds in less than 120 days, a level of effort aided by the many World Health Organization and United Nations staff that are still in the area as part of the response to the Ebola outbreak.  Thankfully, Guinea has not reported any cases of Ebola for several months so officials can devote significant resources to the mass polio vaccine effort.