Delaying vaccines makes them more effectiveNearly all vaccines are more effective when given to older babies. A large study of 7630 babies has found that the antibody response is, for the large majority of vaccines, between 10% and 70% higher for every month of delay. This is a strong argument to delay the start of vaccination, irrespective of the potential safety benefits.
The researchers also found that the presence of maternal antibodies also reduces the effectiveness of the vaccines in babies. This is because the mother passes these antibodies to the baby in the womb. Whilst these antibodies last (they fade away over the first few months) they neutralise any vaccines given to the baby so that the baby makes fewer antibodies of its own. This is a particular problem with the current advice to pregnant women to have the whooping cough vaccine in pregnancy. Many women believe that they are being given a single whooping cough vaccine; in reality they are given a 4-in-1 vaccine covering diphtheria, tetanus and polio as well as whooping cough. If these vaccines are given to the baby at 8 weeks of age the presence of relatively high concentrations of maternal antibodies in the baby render the vaccines less effective. This is important as it may leave children more susceptible to these diseases as they grow older. The authors estimate that a delay in vaccination of between 2 and 5 weeks is necessary to counter this effect of maternal antibodies.
The study concludes. "A delay in age at the first immunisation resulted in a combined beneficial effect on immunogenicity [the strength of the immune response] due to (1) a reduction in maternal antibody interference associated with antibody decay and (2) an increase in infant age.
All this supports our preference at BabyJabs to delay the start of vaccinating until at least 12 weeks.