Babies born to mothers who have had measles have longer immunityA new study published in today's BMJ confirms that babies born to mothers who have had natural measles have longer lasting immunity to measles than babies born to mothers who have been vaccinated against measles. Three months after birth, well over half (60%) of babies born to mothers with natural immunity were still protected against measles compared to only a little over one quarter (29%) of babies born to mothers who had been vaccinated.
At six months of age a quarter (24%) of babies born to mothers with natural immunity were still protected against measles whilst virtually no babies (3%) born to mother who had been vaccinated were protected. By nine months of age all the babies had lost their protection.
This study confirmed what we already knew: that natural maternal immunity results in better and longer-lasting immunity in babies. However, whilst it was previously thought that babies were protected throughout most of their first year of life, this new study shows that immunity wears off more quickly, with nearly all babies born to vaccinated mothers losing all protection by 6 months and all babies born to naturally immune mothers losing protection by 9 months.
This will lead to calls for earlier vaccination with the MMR or single measles vaccine - perhaps as early as 9 months especially where there is an outbreak of measles. The problem with this is that immunisation before one year of age usually requires a second dose of vaccine before the end of the second year because the immune system is not mature enough to respond as efficiently to immunisation at this early age.
19 May 2010