In 2017, researchers in Guinea-Bissau compared the mortality rates of diphtheria, tetanus, and whole cell pertussis (DTP) vaccinated infants between three and five months of age with children who were not yet vaccinated with the DTP vaccine and discovered that mortality rates from all causes were significantly higher among DTP vaccinated infants when compared to infants who were not yet vaccinated. Researchers also noted that if the oral polio vaccine (OPV) was administered simultaneously with the DTP vaccine, all-cause mortality rates decreased; however, they were still significantly higher when compared to infants who had not yet been vaccinated.
