Measles antibodies in cord blood in Portugal: Possible consequences for the recommended age of vaccination.
The optimum age to give the first dose of measles vaccine must balance the risks of disease and vaccine failure. Both are influenced by the levels of transplacentally acquired maternal antibodies. This study was conducted in the Obstetric service of Portuguese hospital, in 2012-2013. Mothers were recruited after informed consent. Measles IgG was measured in 206 cord sera, using a commercial immunoassay. Geometric mean concentrations (and 95% CI) were 1849mIU/ml (1196-2857) and 790mIU/ml (618-1008) in cord sera of newborns from unvaccinated and vaccinated mothers respectively. Maternal age and vaccination status were both associated with the concentration in cord sera, but maternal age was the major predictor. The likely explanation is the same already mentioned in other studies: as a vaccination program progresses, vaccination coverage increases as measles incidence decreases. That results newborns from younger vaccinated mothers having less measles antibodies while the older mothers are more likely to have been infected with the wild virus. As the proportion of vaccinated mothers increase, developed countries tend to anticipate the recommended age of the first dose to 12 months of age. Models using hypothetical measles antibody decay rates in infancy were explored. Anticipating the first dose of MMR1 in Portugal to the age of 12 months might have not been the best decision but results were not conclusive, and arguments supporting or not the anticipation were discussed.
Multidisciplinary Unit for Biomedical Research (UMIB), Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal. Electronic address: aggoncalves@icbas.up.pt.
Guilherme
G
Gonçalves
Public Health Research Centre, National School of Public Health, Universidade NOVA de Lisboa, Avenida Padre Cruz, 1600-560 Lisboa, Portugal. Electronic address: CNunes@ensp.unl.pt.
Carla
C
Nunes
Agrarian Superior School, Polytechnic Institute of Viseu, Quinta da Alagoa - Estrada de Nelas, Ranhados, 3500-606 Viseu, Portugal. Electronic address: jmesquita@outlook.com.
João Rodrigo
JR
Mesquita
Laboratory of Microbiology, Department of Biological Sciences, Faculty of Pharmacy of University of Porto, Rua de Jorge Viterbo Ferreira n.°228, 4050-313 Porto, Portugal. Electronic address: saojose@ff.up.pt.
Maria São José
MS
Nascimento
Multidisciplinary Unit for Biomedical Research (UMIB), Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal; Health Research Unit of School of Health Sciences, Polytechnic Institute of Leiria, Campus 2 - Morro do Lena - Alto do Vieiro, Apartado 4137, 2411-901 Leiria, Portugal. Electronic address: joao.frade@ipleiria.pt.
João
J
Frade
D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D005260:Female; D005312:Fetal Blood / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D008457:Measles / Q000453:epidemiology / Q000276:immunology*; D008458:Measles Vaccine / Q000008:administration & dosage; D008875:Middle Aged; D011174:Portugal / Q000453:epidemiology; D011247:Pregnancy; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult
D000914:Antibodies, Viral; D007074:Immunoglobulin G; D008458:Measles Vaccine
Antibodies; Cord blood; Measles; Recommended age; Vaccination