Davidson et al. (1991)

Cohort

study #2 (subset of study #1) 104 cases for whom all medical records were available (U.S-.Alaska natives)

Exposure to DTwP^† vaccination determined from public health immunization records and computerized Indian Health Service medical records

Occurrence of all illness during the 30-day period before and after DTwP administration. Categories include: any illness; any infectious disease; otitis media; other respiratory infections; temperature > 38°C; and hospitalization

For all illness, 53% of all children had illnesses during 30 days before DTwP immunization and 43% had illnesses during 30 days after DTwP immunization (p = .004); Other illness categories were non-significant; any infectious disease (p = .084); otitis media (p = .501); other respiratory infections (p = 0.285); temp>38°C (p = .724); hospitalization (p = .424)

potential for over matching

Weak evidence relevant to causality; favors no effect of DTwP vaccine