The Missing Link in Hand Hygiene: Why Dose Size Determines Performance

In health care settings, hand hygiene is nonnegotiable. Alcohol-based hand rubs (ABHRs) are firmly established as the primary method for preventing pathogen transmission, and their role in reducing health care-associated infections (HAIs) is foundational. Infection prevention programs worldwide have invested decades of effort into education, monitoring, and culture change around hand sanitizing with ABHRs.

Yet despite this emphasis, hand hygiene adherence rates have plateaued in most acute care facilities. For infection prevention decision-makers, the question should no longer be whether hand hygiene is performed, but whether each documented hand hygiene event is consistently capable of delivering validated protection. As such, the true definition of hand hygiene “adherence” should be expanded to cover the effectiveness of the hand sanitizing event in addition to counting when hand hygiene occurs.

A growing body of evidence suggests that the answer depends on one underappreciated variable: ABHR dose size.

Adherence Is Being Measured; Performance Often Isn’t

Global guidance explicitly states that ABHR must remain wet on the hands long enough to achieve effective antimicrobial action. The Leapfrog Group¹ recommends a minimum wet time of 15 seconds, while the World Health Organization (WHO)² and CDC³ recommend at least 20 seconds.

Wet time, however, is not guaranteed by dispenser activation alone. It is a direct function of the volume of product applied, formulation characteristics, and evaporation rate. Historically, health care has relied on qualitative instructions such as “apply enough to keep hands wet…” without strong, dose-specific evidence showing which volumes reliably meet wet-time thresholds across the wide range of adult hands.

Recent in vivo data now provide the clarity needed to understand ABHR dosing.

Dose Size and Wet-Time Achievement

A controlled evaluation of a leading ABHR foam product across a range of common dispense volumes⁴ (doses of 0.75 mL, 1.0 mL, and 1.5 mL) measured wet time under standardized application conditions. The results demonstrated a clear dose–response relationship.⁵

At 0.75 mL, only half of the participants exceeded the Leapfrog Group’s 15-second wet-time recommendation. Increasing the dose to 1.0 mL modestly improved performance, with approximately 75% exceeding 15 seconds, but this dose failed to meet the WHO and CDC 20-second minimum for most subjects. In contrast, a 1.5 mL dose produced a mean wet time exceeding 27 seconds: all participants surpassed 15 seconds, and the majority (85%) exceeded 20 seconds.⁵

Notably, hand size showed only a weak correlation with wet time. Rather than supporting dose adjustment based on individual anatomy, which would prove an impractical expectation in clinical workflows, the data indicates that a standardized minimum dose of 1.5 mL reliably achieves wet-time adherence across adult hands in a single use.

Below this threshold, effective adherence becomes variable and unpredictable.

ABHR Antimicrobial Efficacy: Dose Determines Outcome Consistency

Wet time is an important adherence metric, but antimicrobial reduction is the outcome that ultimately matters most for infection prevention. A second in vivo study evaluated bacterial reduction using ASTM E2755, a modern test method designed specifically for hand sanitizers and reflective of real-world use conditions.⁶

Using the same ABHR foam formulation as tested for wet time, researchers compared 1.0 mL and 1.5 mL doses. The higher dose achieved significantly greater antimicrobial efficacy as expected, with a mean log₁₀ reduction of 3.30 compared to 2.17 for the lower dose (P < 0.001). Just as important, the 1.5 mL dose showed less variability across subjects, indicating more consistent performance.⁶

These findings reinforce a critical point: Dose size does not simply affect average efficacy, but it also affects reliability across the wide range of people who use hand sanitizer dispensers. Lower doses increase the likelihood of suboptimal hand hygiene events, even when the technique is otherwise appropriate. Even if staff use the product at every recommended moment, under the microscope, the residual transmission risk can remain above the thresholds that hand hygiene guidelines intend to achieve.

The Practical Gap in Current Systems

The broad body of ABHR evidence assembled over the last 30+ years supports these findings. Multiple studies have shown that increasing ABHR volume improves hand coverage, wet time, and microbial reduction^7,8,9,10, while person-to-person variability makes smaller volumes insufficient and risky.¹ Importantly, sensory and acceptability studies indicate that a 1.5 mL dose represents a nice balance point, delivering effective performance without compromising user experience and the practical matter of health care personnel needing to move quickly to deliver quality patient care.¹¹

Despite this, many ABHR dispensing systems commonly used in health care settings deliver volumes below 1.5 mL per actuation^4,12. As a result, a significant proportion of hand hygiene events may be structurally incapable of meeting wet-time and efficacy benchmarks in a single use, regardless of health care worker intent or training.

This creates a disconnect in which hand hygiene is documented as “adherent,” while germ-reduction performance is assumed rather than validated. In practical terms, this means many hand hygiene failures are built into the system, not the behavior.

Reframing adherence for the Next phase of Progress

This is not an indictment of clinicians or infection prevention programs. It reflects the reality that hand hygiene science has evolved faster than some elements of system design and measurement.

Recent US-based infection prevention guidance¹³ acknowledged this shift, explicitly stating that hand sanitizer dispenser volume should be considered a dose, that the dose must be sufficient to cover all hand surfaces, and that the dispensed volume should be consistent with volumes shown to be efficacious (ie, efficacy test results using the ABHR formulation and dose delivered to health care worker hands).

The convergence of modern wet-time data, appropriate in vivo efficacy testing, and updated guidance supports a clear conclusion: a target of 1.5 mL ABHR dose represents a scientifically defensible lower risk of germ transmission threshold that aligns antimicrobial efficacy with global ABHR guidance plus adherence standards in a single use, independent of hand size and person-to-person variability.

Why This Matters for Patient Safety

Hand hygiene remains one of health care’s most powerful patient safety tools. Optimizing dose size serves only to strengthen it. When doses are standardized and evidence-based, hand hygiene performance becomes more predictable, variability and risk decrease, and each hand hygiene event is more likely to deliver its full protective benefit.

For infection prevention teams focused on the next increment of improvement in HAI reduction, dose size deserves the same level of attention historically given to formulation, technique, and monitoring.

Hand hygiene already works. Ensuring that every hand sanitizing event performs as intended represents the next critical advance.

Reference List

1. The Leapfrog Group. Handwashing. Hospital and Surgery Center Ratings. 2025. Accessed March 5, 2026. https://ratings.leapfroggroup.org/measure/hospital/2025/handwashing

2. WHO guidelines on hand hygiene in Health Care. World Health Organization. 2009. Accessed March 5, 2026. https://www.who.int/publications/i/item/9789241597906.

3. Clinical safety: Hand hygiene for healthcare workers. Centers for Disease Control and Prevention. 2024. Accessed March 5, 2026. https://www.cdc.gov/clean-hands/hcp/clinical-safety/index.html.

4. Smith NM, Bánsághi S, Chen N, et al. Importance of dosing: Analysis of touch-free hand hygiene dispensers for consistency. American Journal of Infection Control. 2025;53(6):696-700. doi:10.1016/j.ajic.2025.02.007.

‌5. Oxley-Smith G, Arbogast JW, Ormandy K. From insight to impact: New research on ABHR dose supports continued journey to hand hygiene excellence. Poster presented at: International Conference on Prevention & Infection Control (ICPIC) 2025; 2025; Geneva, Switzerland. Abstract P-1241.

6. Arbogast JW, Oxley-Smith G, Brill FHH, Ormandy K. In vivo assessment of ABHR dose size on antimicrobial efficacy – 1.5 mL is optimal. Poster presented at: Australian College for Infection Prevention and Control (ACPIC) 2025 Conference; 2025; Hobart, Tasmania, Australia.

7. Macinga DR, Beausoleil CM, Campbell E, et al. Quest for a realistic in vivo test method for antimicrobial hand-rub agents: Introduction of a low-volume hand contamination procedure. Applied and Environmental Microbiology. 2011;77(24):8588-8594. doi:10.1128/aem.06134-11.

8. Macinga DR, Shumaker DJ, Werner H-P, et al. The relative influences of product volume, delivery format and alcohol concentration on dry-time and efficacy of alcohol-based hand rubs. BMC Infectious Diseases. 2014;14(1). doi:10.1186/1471-2334-14-511 .

9. Zingg W, Haidegger T, Pittet D. Hand coverage by alcohol-based handrub varies: Volume and hand size matter. American Journal of Infection Control. 2016;44(12):1689-1691. doi:10.1016/j.ajic.2016.07.006.

10. Wilkinson MAC, Ormandy K, Bradley CR, Fraise AP, Hines J. Dose considerations for alcohol-based hand rubs. Journal of Hospital Infection. 2017;95(2):175-182. doi:10.1016/j.jhin.2016.12.023.

11. Greenaway RE, Ormandy K, Fellows C, Hollowood T. Impact of hand sanitizer format (gel/foam/liquid) and dose amount on its sensory properties and acceptability for improving hand hygiene compliance. Journal of Hospital Infection. 2018;100(2):195-201. doi:10.1016/j.jhin.2018.07.011.

12. Macinga DR, Edmonds SL, Campbell E, Shumaker DJ, Arbogast JW. Efficacy of novel alcohol-based hand rub products at typical in-use volumes. Infection Control &amp; Hospital Epidemiology. 2013;34(3):299-301. doi:10.1086/669514.

13. Glowicz JB, Landon E, Sickbert-Bennett EE, et al. Shea/IDSA/APIC Practice Recommendation: Strategies to prevent healthcare-associated infections through hand hygiene: 2022 update. Infection Control &amp; Hospital Epidemiology. 2023;44(3):355-376. doi:10.1017/ice.2022.304