Clinical Scorecard: Trends in Neutralizing Antibody Levels Against Enterovirus D68 in Adults Amid the COVID-19 Pandemic
At a Glance
Category
Detail
Condition
Neutralizing-antibody responses to enterovirus D68
Key Mechanisms
Neutralizing antibodies block viral infection and provide evidence of virus-specific immunity, although their precise protective role in human EV-D68 infection remains unclear
Target Population
194 adult retail workers aged 18 years or older in Quebec City, Canada
Care Setting
Longitudinal serologic research within a prospective SARS-CoV-2 cohort during the COVID-19 pandemic
Key Highlights
EV-D68 neutralizing-antibody seropositivity exceeded 85% at both visits.
Overall geometric mean titer declined significantly from 69 to 59 during 48 weeks of follow-up.
Ninety-three percent of participants had less than a 4-fold change in titers.
Significant declines occurred among women, participants aged 40–59 years, and participants with obesity or diabetes.
Six participants (3%) had a titer increase of at least 4-fold.
Eight participants (4%) had a titer decrease of at least 4-fold.
Guideline-Based Recommendations
This longitudinal serologic study did not establish clinical guidelines for EV-D68 diagnosis, treatment, or antibody monitoring.
Diagnosis
EV-D68 neutralizing antibodies were measured using a live microneutralization assay.
A neutralizing titer of at least 1:20 defined seropositivity in this study.
The assay used a 2014 EV-D68 clade B1 strain and was not evaluated as a diagnostic test for active infection.
Seropositivity indicated previous antibody exposure but did not establish when infection occurred.
Management
No licensed antiviral agents or vaccines for EV-D68 were available, according to the study background.
The study did not evaluate treatment, vaccination, or clinical management strategies.
Neutralizing-antibody levels should not be interpreted as an established measure of clinical protection because their precise protective role in humans remains unclear.
Monitoring & Follow-up
Paired serum samples were collected 48 weeks apart to evaluate changes in neutralizing-antibody titers.
A change of at least 4-fold defined a significant individual increase or decrease.
Studies using contemporary EV-D68 strains in similar adult cohorts are needed to characterize cross-subclade immunity.
The study did not establish a routine clinical antibody-monitoring schedule.
Risks
EV-D68 causes acute respiratory illness and can lead to acute flaccid myelitis.
Adults with underlying conditions may also be affected, although infections have been reported mainly among children.
Cross-neutralization with other nonpolio enteroviruses may have contributed to the high observed seropositivity.
Testing only a historical clade B1 strain may not have captured the full breadth of responses to more recent subclades.
Patient & Prescribing Data
The study included 194 retail workers with a median age of 41 years; 57% were women. Common comorbidities included obesity, arterial hypertension, chronic lung disease, and diabetes mellitus.
The study measured antibody responses and did not evaluate medications, prescribing practices, vaccines, or treatment outcomes.
Clinical Best Practices
Interpret neutralizing-antibody results as research measures of virus-specific immunity rather than diagnostic evidence of active EV-D68 infection.
Recognize that high seropositivity is consistent with substantial previous exposure but may partly reflect cross-neutralization.
Interpret marked titer increases cautiously because they may indicate EV-D68 exposure or cross-reactivity with another enterovirus.
Account for EV-D68 subclade differences when evaluating neutralization results.
Support serologic surveillance in adults using contemporary viral strains.
Related Resources & Content
Dynamics of Neutralizing Antibodies Against Enterovirus D68 in Adults During the COVID-19 Pandemic — Rahajamanana VL, Rabezanahary H, Arroyave A, et al. International Journal of Infectious Diseases. 2026;171:109008. doi:10.1016/j.ijid.2026.109008.
