By Dave Revelli, Research Scientist, ABSL-3 Facility Director
One of the few positive outcomes of the COVID-19 pandemic was the transformative way the scientific community collaborated to accelerate and validate a vaccine. Researchers identified, developed and deployed vaccines within a year of the onset of the pandemic, an achievement that has never before been accomplished in such a short timeframe.
Yet the early months of the pandemic revealed a persistent vulnerability in infectious disease response systems: the interval between emergence of a novel pathogen and availability of targeted countermeasures. During that period, clinicians often work with limited information, uncertain treatment pathways, and escalating disease burden.
This preparedness gap has renewed attention on host-directed and threat-agnostic therapies, approaches designed to support or modulate the patient’s physiological response to infection rather than target a specific virus or bacterium. These therapies are gaining interest as part of a broader infectious disease strategy focused on resilience, rapid response capability, and preparedness for pathogens that have not yet emerged.
Expanding the Therapeutic Focus from Pathogen to Host
Host-directed therapies are not new concepts. Clinical medicine routinely uses supportive interventions like intravenous fluids, fever reduction strategies and corticosteroids to stabilize physiological responses during illness. The distinction lies in expanding this concept into more sophisticated therapies that intentionally regulate inflammation, immune signaling pathways, or coagulation cascades associated with severe infectious diseases.
The clinical use of dexamethasone in hospitalized COVID-19 patients illustrates the potential impact of this approach. Investigators found that corticosteroid treatment improved outcomes in critically ill patients experiencing severe inflammatory responses. The benefit emerged from moderating host-mediated tissue damage, particularly pulmonary inflammation, instead of directly inhibiting viral replication. Timing proved essential. Therapeutic benefit depended on disease stage and severity, highlighting the complexity of immune modulation in infectious disease treatment.
These observations underscore an important principle for future preparedness efforts. Host-directed therapies function most effectively as complementary tools within a layered response strategy that includes diagnostics, antivirals, antibiotics, vaccines, and supportive care. Their value may be greatest during the early phases of an outbreak when pathogen-specific interventions remain under development.
Why Emerging Infectious Threats Require Broader Preparedness Strategies
Emerging infectious diseases consistently challenge assumptions about origin, transmission, and severity. Viral spillover from animals, antimicrobial resistant bacterial infections, and geographically localized outbreaks all contribute to an increasingly unpredictable landscape. Researchers continue to evaluate which pathogens may pose future pandemic risks, while acknowledging that preparedness requires flexibility for scenarios that simply can’t be predicted.
A threat-agnostic therapeutic approach addresses this uncertainty by focusing on biological processes shared across multiple diseases. Inflammation, dysregulated immune activation, endothelial injury, and abnormal coagulation pathways recur in diverse infectious syndromes. Targeting these common mechanisms could provide earlier intervention opportunities while pathogen identification and targeted countermeasure development proceeds.
Scientific Challenges: Biomarkers, Timing, and Patient Variability
Developing such therapies presents significant research and scientific challenges. Biomarker discovery remains a central priority because clinicians need precision in determining which patients will benefit from immune modulation and at what point during disease progression intervention should occur. Infectious diseases often trigger dynamic physiological responses that evolve rapidly over time. An intervention that improves outcomes in one stage may have limited efficacy or unintended consequences in another.
Patient heterogeneity adds further complexity. Genetic background, age, comorbidities, and baseline immune function all influence treatment response. Future host-directed therapies will likely depend on increasingly refined patient stratification methods and predictive biomarkers capable of guiding personalized intervention strategies.
Artificial intelligence may accelerate progress in this area by integrating findings across large, fragmented datasets. Cross-pathogen analyses could reveal recurring biological signatures associated with severe disease and identify candidate pathways for broad therapeutic targeting. AI-enabled approaches may also improve biomarker discovery and enhance understanding of temporal immune responses across populations.
Sustaining Preparedness Requires Investment Beyond Crisis Periods
Advancement will require more than scientific insight. Sustained infrastructure and funding remain equally important. Pandemic preparedness research frequently experiences cycles of urgency followed by decline once immediate threats subside. This pattern limits continuity, slows translational progress, and weakens readiness for subsequent outbreaks.
Long-term investment in clinical trial networks, preclinical modeling capabilities, and collaborative research ecosystems supports preparedness independent of current headlines. Large multinational studies conducted during COVID-19 demonstrated the value of maintaining trial infrastructure capable of rapid activation. Continued investment could shorten response timelines during future public health emergencies.
Regulatory frameworks also need to evolve to accommodate therapies with broad biological effects and multiple potential applications. Existing approval models often emphasize pathogen-specific indications, whereas host-directed interventions could span diverse infectious conditions. Adaptive regulatory pathways may become increasingly important as broad-spectrum immune modulators enter development pipelines.
Government agencies and international preparedness organizations will continue to influence this landscape through funding priorities and strategic partnerships. Programs supporting pandemic readiness increasingly recognize that preparedness depends on maintaining capabilities before emergencies arise. Agencies focused on biodefense and emerging infectious diseases play a central role in advancing host-directed therapeutic research and sustaining translational momentum.
Looking Forward – A Layered Model of Pandemic Response
Future infectious disease preparedness depends on integrated defense systems rather than singular technological solutions. Vaccines, pathogen-specific therapeutics, diagnostics, surveillance platforms, and host-directed interventions each address different stages of response. Strength emerges from combining these capabilities into coordinated strategies designed for uncertainty.
The next major infectious threat may emerge from a familiar pathogen, an antimicrobial resistant organism, or an entirely novel source. Building preparedness for that future requires investment in approaches capable of functioning before precise answers exist. Host-directed therapies offer a compelling framework for expanding resilience by focusing not only on defeating pathogens, but also on strengthening the biological systems that determine patient outcomes.