Relationship between biochemical markers and measles viral load in patients with immunologically naive cases and secondary vaccine failure: LDH is one of the potential auxiliary indicators for secondary vaccine failure

Abstract

This study investigated the correlation between biochemical markers and viral load among 38 measles cases, including 15 immunologically naive patients and 23 patients with secondary vaccine failure (SVF). We examined four biochemical markers, namely, aspartate aminotransferase, alanine aminotransferase, C-reactive protein, and lactate dehydrogenase (LDH) and their relationship between virus genome copy numbers in peripheral blood mononuclear cells (PBMCs) and throat swabs as well as the concentration of measles-specific IgG. Although viral genome copies in both clinical specimens showed a significant correlation with specific IgG concentration, they had a higher correlation in PBMCs (Pearson's product-moment correlation coefficient, −0.662; p < .0001) than in throat swabs (Spearman's rank correlation coefficient, −0.443; p = .0078). The viral load in PBMCs also significantly correlated with LDH values (correlation coefficient, 0.360; p = .036). Thus, the serum LDH level might be a potential auxiliary indicator to distinguish immunologically naive patients with measles from those with SVF.Measles is a highly contagious viral disease characterized by a generalized rash and severe fever. Since 1968, when an effective live attenuated measles-containing vaccine (MCV) was developed, the incidence and mortality rate of measles has decreased globally. 1 After introducing routine two-dose schedules with the measles-rubella vaccine in 2006, 2 the number of reported measles cases was drastically reduced in Japan, 3 and in 2015, measles elimination in Japan was verified by the World Health Organization Western Pacific Regional Office. 4 After the elimination of measles, outbreaks related with patients who had previously received an MCV have become an issue. According to the National Institute of Infectious Diseases (NIID), approximately 35% of patients with measles reported in 2019 had been vaccinated. 3 These measles infections were induced by primary vaccine failure (PVF) or secondary vaccine failure (SVF). PVF is a failed response to vaccination and is observed in approximately 2%-5% of children who receive a single MCV dose. 1 Patients with PVF are more likely to present severe clinical signs similar to unvaccinated patients and an immunological reaction (i.e., low