7.5.2  Serious vaccine reactions

On rare occasions, a reaction to a particular vaccine can be serious, even so serious as to be life-threatening. When serious problems follow an immunization, rumours are likely to circulate in the community that immunization is not safe, and children may then not be brought by parents for immunization. This will have a damaging effect on the spread of infectious diseases in the community.

  • Can you explain why a measles epidemic is likely to occur in a community if not enough children receive measles vaccine?

  • [You learnt about herd immunity in Study Session 1.] The reason is because the herd immunity in the population will be too low to prevent the measles viruses from spreading; it can pass from infected children to the many susceptible children who have not be immunized.

Table 7.2 summarises the possible serious adverse reactions to different vaccines that you may very rarely encounter. For example, acute flaccid paralysis following OPV occurs about once in every 1–10 million children vaccinated.

Table 7.2  Possible onset of serious vaccine reactions.
VaccineSerious adverse eventEstimated period of onset (time after immunization)
BCGAbscess (collection of pus)1–6 weeks
Swollen lymph nodes in the armpit2–6 months
Bone disease1–12 months
Pentavalent or DPTSevere acute allergic reaction 0–1 hour
Continuous screaming 0–24 hours
Brain disease, seizures (convulsions, fits)0–3 days
Abscess1–6 weeks
HepBSevere acute allergic reaction0–1 hour
Paralysis1–6 weeks
MeaslesSevere acute allergic reaction0–1 hour
Abscess1–6 weeks
OPVAcute flaccid paralysis4–30 days
TT (women)Severe acute allergic reaction0–1 hour
Nerve damage in the arm2–28 days

However, most adverse events following immunization are not due to reactions caused by the vaccine. We will look at the other causes of AEFIs next.

7.5.1  Mild reactions to vaccines

7.5.3  Other causes of AEFIs