Vaccines and the risk of acute disseminated encephalomyelitis.

BACKGROUND

It is important to examine the risk of Acute disseminated encephalomyelitis (ADEM) after vaccination.

METHODS

We conducted a nested case-control study between January 2011 and December 2015. Four controls per case were matched for age, gender, address. An independent expert committee validated the diagnoses of cases and controls. Data on vaccinations were obtained from computerized vaccination records. The analyses were conducted with the use of conditional logistic regression.

RESULTS

The analyses include 272 cases of ADEM and 1096 controls. No increase in the risk of ADEM was observed for vaccination against hepatitis B, influenza, polio(live), diphtheria, pertuss(acellular), tetanusis, measles, mumps, rubella, Japanese Encephalitis, meningitis, hepatitis A, varicella and rabies vaccines. Vaccine was associated with a statistically significant increase in risk in the 31-60-day exposure interval (OR, 4.04 [95% CI, 1.07-12.69]), but not the 0-30 and 61-180-day interval. There was no association between vaccine received and the recurrence of ADEM.

CONCLUSIONS

Findings from the present study do not demonstrate an association of vaccines with an increased risk of ADEM and its recurrence among either paediatric (≤18 years) or adult (>18 years) individuals within the 180 days after vaccinations. The finding in children in the 31-60 day risk interval is likely coincidental and was not confirmed in separate self-control analyses.