Very rarely, fever above 40.5 °C, fits, collapse and shock, severe irritability with persistent crying and screaming attacks or drowsiness, confusion and brain damage (encephalopathy) may follow pertussis immunisation. The risk of fever and fits is one in a thousand infants immunised with pertussis vaccine while the risk of encephalopathy is one in a million. If a serious rection occurs, pertussis vaccine must not be given again.
A new, safer, cell-free pertussis vaccine, with fewer local and systemic side effects, is now available. However, parents have to pay for this as it is expensive.
Fever above 40.5 °C within 2 days, fits within 3 days or encephalopathy within 7 days of DPT immunisation must be reported to the local health authorities.