Wednesday, February 29, 2012

Early diphtheria-tetanus-pertussis vaccination associated with higher female mortality and no difference in male mortality/ Arch Disease Childhood

Peter Aaby's group from Statens Serum Institute, Denmark, has been studying the effects of many vaccines in African children for many years.  The group has found some similar results in the past.  The fact that they continue to see the same effect (huge increases in death rates in young vaccinated female infants, increases not seen in unvaccinated females) is extremely troubling, and calls into question the rationale for early female DPT vaccinations in countries with already high mortality rates.

From the original article:  Early diphtheria-tetanus-pertussis vaccination associated with higher female mortality and no difference in male mortality in a cohort of low birthweight children: an observational study within a randomised trial:

What is already known on this topic

  • Live vaccines such as measles vaccine and Bacille Calmette-Guerin have non-specific beneficial effects in areas with high mortality.
  • Previous studies from several low-income African countries have suggested that inactivated vaccines, including diphtheria-tetanus-pertussis (DTP), may have non-specific negative effects for survival of girls.
  • WHO sponsored studies which have found a beneficial effect of DTP have major methodological problems.

What this study adds

  • Adjusted for nutritional status, DTP vaccinated children, particularly girls, had threefold higher mortality between 2 and 6 months of age.
  • Nutritional status was a strong predictor of mortality among boys but not girls.
  • There is a continuing contradiction between studies of DTP from low-income countries and current policy.

    "Adjusting for mid upper arm circumference (a surrogate measure of nutritional status), the overall effect for DTP vaccinated children was 2.62 (95% CI 1.34 to 5.09); the death rate ratio was 5.68 (95% CI 1.83 to 17.7) for girls and 1.29 (95% CI 0.56 to 2.97) for boys (p=0.023, homogeneity test). While anthropometric indices were a strong predictor of mortality among boys, there was little or no association for girls."

    [If these adjustments are accurate, it seems both girls and boys died at higher than expected rates.--Nass]

1 comment:

Meryl Nass, M.D. said...

Studied in a different way, Aaby's group found up to a 20-fold increase in female twin mortality after MMR compared to its male twin.

Int J Epidemiol. 2004 Apr;33(2):367-73.
Divergent female-male mortality ratios associated with different routine vaccinations among female-male twin pairs.
Aaby P1, Jensen H, Rodrigues A, Garly ML, Benn CS, Lisse IM, Simondon F.
Author information
Observational studies have suggested that vaccinations have non-specific effects that differ by sex. In the absence of randomized trials, studies of female-male twin pairs would allow us to investigate whether an intervention had sex-specific effects on survival. We therefore examined mortality patterns among female-male twin pairs according to vaccination status. Design We identified female-male twin pairs using the population registers from one urban district and three rural studies from Guinea-Bissau and Senegal and examined the female-male mortality ratio (MR) according to the last vaccine received among pairs in which a death occurred before 18 months of age. As background information, we examined sex- and age-specific mortality patterns in the pre-vaccination era. Subjects In all, 626 female-male twin pairs identified between 1978 and 2000.
There was no sex difference in mortality for boys and girls in the pre-vaccination era. In the combined analysis of all studies, the female-male MR was 0.25 (95% CI: 0.05, 0.93) for pairs having received Bacille Calmette-Guerin (BCG) as the last vaccine, 7.33 (95% CI: 2.20, 38.3) for pairs having received diphtheria, tetanus, pertussis (DTP) as the last vaccine, and 0.40 (95% CI: 0.04, 2.44) for pairs having received measles vaccine as the last vaccine. The female-male MR varied significantly for BCG compared with DTP (exact test of homogeneity, P < 0.001) and for DTP compared with measles vaccine (exact test of homogeneity, P = 0.001).
Non-specific effects of routine vaccinations are likely to be important and influence sex-specific mortality patterns in areas with high mortality. The effects of vaccines need to be considered in the planning of immunization programmes for low-income countries.