Letter

Non-specific effects of vaccination

BMJ 2005; 330 doi: 10.1136/bmj.330.7495.844-b (Published 7 April 2005)
Cite this as: BMJ 2005;330:844.3

Access to the full text of this article requires a subscription or payment. Please log in or subscribe below.

Survival bias may explain findings

  1. Peter Aaby, professor (psb@mail.gtelecom.gw),
  2. Henrik Jensen, senior statistician,
  3. Christine Stabell Benn, senior researcher,
  4. Ida Maria Lisse, registrar
  1. Bandim Health Project, Danish Epidemiology Science Centre, Statens Serum Institute, Apartado 861, Bissau, Guinea-Bissau

    EDITOR—Vaugelade et al found the BCG and diphtheria-tetanus and pertussis vaccines (DTP) to be associated with reductions in mortality greater than expected from disease prevention.1 However, as they admit, dead vaccinated children may have been misclassified because their vaccination cards were destroyed.

    In a survival analysis using vaccination dates as time dependent covariates, surviving children change status at date of vaccination even though vaccinations …

    Access to the full text of this article requires a subscription or payment

    Subscribe

    Article access

    Article access for 1 day

    Purchase this article for £20 $30 €32*

    The PDF version can be downloaded as your personal record

    * Prices do not include VAT

    Rapid responses

    THIS WEEK'S POLL

    Read related article

    See previous polls

    BMJ most popular