What are the advantages of the oral poliovirus vaccine (OPV)?

• A. OPV is injected, expensive, and induces only systemic immunity
• B. OPV is given as a nasal spray and induces mucosal immunity only
• C. OPV requires refrigeration but provides no immunity
• D. OPV is orally administered, inexpensive, and induces both systemic and intestinal immunity

Answer: (D)

The key advantage of the oral poliovirus vaccine is its combination of easy administration, low cost, and the ability to generate immunity both systemically and in the gut. Because OPV is given by mouth, it can be distributed quickly in mass campaigns without needles, making it inexpensive and logistically simple. The attenuated virus replicates in the gastrointestinal tract, inducing mucosal (intestinal) immunity, including secretory IgA, as well as systemic immunity through circulating antibodies. This dual protection not only guards against paralytic disease but also reduces intestinal viral shedding, helping to interrupt transmission in communities. That combination—oral delivery, low cost, and dual (systemic and intestinal) immunity—best explains why OPV has been such a powerful tool in poliovirus eradication efforts. The other descriptions misstate the route, the type or scope of immunity, or cost, so they don’t fit OPV’s true advantages.