Why do people still get polio in some countries and not in others?
On a busy street in Karachi, Pakistan, a health care worker kneels down so she's eye to eye with a toddler. She squeezes two drops of liquid onto the child's tongue. Then she takes out a purple marker and colors the child's pinkie fingernail so everyone can see that this toddler is now vaccinated ag
<p>On a busy street in Karachi, Pakistan, a health care worker kneels down so she's eye to eye with a toddler. She squeezes two drops of liquid onto the child's tongue. Then she takes out a purple marker and colors the child's pinkie fingernail so everyone can see that this toddler is now vaccinated ag</p>