Hypotonic-hyporesponsive episode following acellular pertussis vaccination

The introduction of routine vaccination against whooping cough caused a drastic decline in the incidence of this disease, but remains today a public health problem even in countries with high vaccination coverage. However, with this decrease in cases, there were an emergence of neurological severe adverse events such as the "hypotonic-hyporesponsive episodes" (HHE), characterized by sudden loss of muscle tone associated with poor response to stimuli and skin pallor or cyanosis. The HHE is a rare phenomenon after administration of pertussis vaccine, but it is essential for health workers recognition of such reactions, especially in the 48 hours following vaccination. Although sometimes can become difficult to attribute a causal relationship between vaccine administration and an adverse effect, any suspicious events should be reported.