A baby aged one month and 10 days died at a Madrid hospital on Thursday from pertussis, more commonly known as whooping cough, regional health authorities reported.
The infant had been in the pediatric intensive care unit of La Paz Hospital for two days.
Medical sources noted that the pertussis vaccine cannot be administered before two months of age.
Three other babies have died of whooping cough in Spain in a little over two months – one in Cuenca, one in Seville and one in Málaga.
On Thursday, the Madrid regional health department began inoculating women in late pregnancy stages with the pertussis vaccine, to ensure that their babies are born with the immunization.
Until now, this option was not included in the public health plan and women had to purchase the shots themselves.
The Málaga case is under investigation following claims that the mother tried to get immunized for whooping cough while she was pregnant but was unable to find the vaccine at local pharmacies.
English version by Susana Urra.