In a recent study published in Nature Microbiology, researchers investigated the dynamics of measles immunity at birth and following vaccination. Researchers found that a single dose of the measles jab is up to 2.6 times more likely to be completely ineffective in children born by C-section.
Study: Dynamics of measles immunity from birth and following vaccination. Image Credit: PhotobyTawat/Shutterstock.com
Background
Measles remains a danger to human health despite immunization efforts. Mother antibodies can diminish vaccine-induced immunity, although the effect of pre-existing immunity levels and maternal and infant characteristics on vaccination responses is uncertain.
The measles-containing vaccine (MCV) protects against measles virus infection, although breakthrough infections in vaccinated individuals impede eradication. Debates concerning individual vaccine responses and the significance of catch-up vaccinations complicate the relationship between maternally derived and vaccine-induced antibodies.
Large-scale investigations are required to determine the influence of catch-up dosages on individual-level immunological responses.
About the study
In the present study, researchers quantitatively examined measles antibody fluctuation in the initial few years of life and after vaccination.
Researchers in China examined two longitudinal community-based serological cohorts of children from 2013 to 2018, focusing on measles antibody dynamics in the first years of life. Between September 2013 and August 2018, they included 1,505 patients with full measles vaccination records and antibody titers in the study.
There were no spontaneous measles infections. The team used serological data from these cohorts and empirical models to recreate antibody trajectories from birth, allowing them to objectively examine the population-level effects of various vaccination regimens and evaluate vaccine policy at the national level.
The cohort research investigated pediatric enterovirus A71 infections: a mother-neonate cohort and a population-based cohort of children aged one to nine years.
The infant cohort included local pregnant mothers and their newborns at birth and followed up at two months, four months, six months, 12 months, 24 months, and 36 months. The infant cohort enrolled individuals aged one to nine years and followed up six times between 2013 and 2016, almost every six months.
The researchers performed mathematical modeling to predict measles antibody levels throughout time and investigated maternal-level antibody trends and infant immunological responses to the measles-containing vaccine.
They examined the causes of newborn MCV-induced immunological titers, the implications of different MCV vaccination regimens on population-level immunity, and the role played by catch-up dosages in developing individual immunological profiles.
The team collected socio-demographic and obstetric information via questionnaires and retrieved vaccination and infection data from official records. They screened all samples for anti-measles virus immunoglobulin G (IgG) antibodies using enzyme-linked immunosorbent assays (ELISA).
Results
The study found that measles antibody evolution is significantly predictive from birth at the individual level, including after immunization. Cesarean section deliveries were associated with a 2.6-fold increase in the likelihood of primary vaccination failure, emphasizing the long-term immunological effects of the delivery mode.
Maternal measles antibody titers tested in umbilical cord blood samples at delivery showed a 6.4 mean log concentration, with a strong association of umbilical cord blood with concentrations in the mothers and a 1.1 mean ratio of antibody transfer.
The researchers found significant disparities in titers based on the infant gender, with male cord blood titers being 1.0 times higher on average than female newborns. The relative differences in titers increased to 1.1 by the age of seven months and before administering the initial MCV dosage (MCV1).
After the initial MCV dosage, female newborns had 1.0 times higher concentrations than male newborns (190 in number), reversing the trend. The team discovered that exponential decay might accurately recreate the reported maternal concentration levels, outperforming power-law decay.
The mean log maternal antibody half-life was 181 days, with population mean log concentrations decreasing to 4.4 by four months and 2.8 by eight months of age.
The team noted a robust link between maternal antibody concentrations just before MCV1 and peak MCV1 responses, with each maternal log-concentration increase resulting in a 1.4 reduction in MCV1-induced peak log-concentrations.
Controlling for maternal antibody titers, female newborns showed 0.2 higher peak log-concentration increases than male infants. MCV1-induced peak log-concentration increases were unaffected by infant age or vaccine type.
The team observed continuous long-term log concentration reductions, falling from the mean of 7.3 at two years of age to 6.8 at five years and 6.5 at eight years. Children unresponsive to MCV2 had higher immunological responses to MCV2 than MCV1 responders.
Post-MCV2, there were no discernible differences in peak log concentrations between MCV1 responders and non-responders, emphasizing the critical function of MCV2 in protecting children who did not generate immune responses to MCV1.
Conclusion
The study found that measles-containing vaccine delivery at 12 months could enhance antibody concentrations and immune protection while increasing the number of susceptible babies, highlighting the delicate balance between early-life vulnerability and post-vaccination immunity.
The ideal vaccination timing depends on an age-structured population immunity profile and the danger of a measles epidemic. Population-wide seroprevalence research could improve the understanding of age-specific immune profiles and advise targeted vaccination programs.
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