In recent years, the approval and use of new background therapies for multiple sclerosis has led to a remarkable improvement in the modification of the evolution of the disease and in the accumulation of disability. These types of drugs decrease the function of the immune system. Consequently, they reduce flare-ups and new lesions against the brain and spinal cord, but at the same time, they increase the risk of infections.

"As a prevention strategy, it is recommended to vaccinate patients before administering immunosuppressive drugs", explains Dr. René Carvajal, neurologist at Cemcat and Vall d'Hebron and researcher in the Clinical Neuroimmunology group of the Vall d’Hebron Research Institute (VHIR). "Especially in the case of some vaccines, such as chickenpox or measles, which contain attenuated viruses, since in people whose immune system has been weakened by treatment, they can cause infection by the vaccine virus". The usual protocol consists of administering two doses of the vaccine, respecting the four-week interval between doses. In addition, after receiving the second dose, patients must wait another four weeks to start treatment, which means a delay of two months.

Single-dose immunization could reduce the waiting time, but it was not known whether this strategy would offer sufficient protection. To answer this question, Carvajal, along with other researchers, under the leadership of Dr. Mar Tintoré, neurologist and head of care at Cemcat, clinical head of the Neurology Service at the Vall d'Hebron University Hospital and principal researcher of the Clinical Neuroimmunology group at the VHIR, and Dr. Susana Otero-Romero, researcher at Cemcat, assistant physician at the Preventive Medicine Service at the Vall d’Hebron University Hospital and head of the Epidemiology and Public Health group at the VHIR, have carried out a study involving 96 patients with multiple sclerosis. The research, published in the Multiple Sclerosis Journal, compares the effectiveness of administering one dose versus the standard two-dose regimen.

According to the results, 66.6% of patients who received a single dose of measles or chickenpox had sufficient antibody levels to fight the infection. "In other words, the administration of a single dose of the vaccines protects two out of three patients", Otero-Romero remarked. As for the patients included in the standard group, almost all of them, 97.2%, acquired good levels of immunization.

In the words of Tintoré, "the study supports the strategy of vaccinating patients with a single dose, especially in those cases where it is necessary to start immunosuppressive treatment immediately. In addition, we also advocate implementing in clinical practice the analysis of antibody levels to confirm that the level of protection is adequate".

The work has counted with the collaboration of the Services of Preventive Medicine and Microbiology of the Vall d’Hebron University Hospital. It has also been possible thanks to the clinical grant awarded by the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) and the research grant awarded by VHIR to René Carvajal and the funding received from the Instituto de Salud Carlos III.