729 hepatitis A specimens without recruiting a single patient

1. Background

The sponsor commissioned a Hepatitis A Total antibody remnant-specimen collection program to support immunoassay verification work on a Hepatitis A serological assay.² Verification across the analytical range required a substantial pool of antibody-positive specimens drawn from the clinical-testing population; the program was structured as remnant-specimen sourcing — residual material from clinical testing already performed for clinical care — rather than as fresh-collection from consented research subjects.

Remnant sourcing is a fundamentally different operational frame from the recruitment-based programs reported elsewhere in this engagement series. Subjects in a remnant program have already had specimens drawn and tested for clinical reasons; the operational unit of work is not the patient visit but the partner laboratory’s monthly antibody-positive testing volume. The work shifts from site-initiation visits and patient consent to specimen-handling agreements, regulatory documentation, and shipment-cadence management with the partner.

2. Constraints encountered

Three constraints shaped the execution plan:

1. Partner laboratory testing volume sets the monthly ceiling

   The number of antibody-positive remnant specimens available in any month is bounded by the partner laboratory’s clinical Hepatitis A serological testing volume in that month. RDI does not drive specimen availability; the partner’s clinical-care testing volume does. The program plan accommodated month-to-month variation in availability rather than expecting a flat monthly cadence.

2. Regulatory and de-identification documentation up-front

   Remnant-specimen programs operate under IRB-exempt determinations subject to robust de-identification at the source partner laboratory. The program required up-front documentation of the partner’s de-identification SOPs, validation of the data-stripping process, and execution of a master specimen-handling agreement before any specimen flow began. This work front-loaded the program timeline but had no ongoing per-month overhead.

3. No second specimen pool if the first under-delivers

   A single-partner remnant program has no contingency network. If the partner’s testing volume falls short of the program target, the program either runs longer or under-delivers; there is no equivalent of activating additional sites. Partner selection had to weight historical testing-volume disclosure heavily; the program target was set conservative against the partner’s monthly volume baseline rather than against best-case projections.

3. Methods

RDI executed the program through a single clinical-laboratory partner. Three operational moves are reported here in order of implementation.

3.1. Partner identification and qualification (Apr–May 2023)

The lead clinical-laboratory partner was identified through the network of RDI’s commercial-lab relationships and qualified against three independent criteria: historical Hepatitis A serological testing volume sufficient to sustain the program target across the available window; pre-existing de-identification SOPs validated against research-use standards; and operational capacity to execute monthly shipments on a fixed cadence without disrupting the partner’s clinical-care workflow.

3.2. Master specimen-handling agreement and IRB-exempt determination (May–Jun 2023)

A master specimen-handling agreement was executed between RDI and the partner laboratory in May 2023, covering specimen ownership, de-identification methodology, shipping logistics, sponsor handoff, and the program’s regulatory framing. An IRB-exempt determination letter was issued in late May 2023 against the de-identified-specimen and no-patient-contact protocol.

3.3. Recurring monthly shipment cadence (Jun 2023–Mar 2024)

Specimens flowed under a recurring monthly shipment cadence. The partner laboratory aggregated antibody-positive remnant specimens through each calendar month, executed de-identification against the agreed SOP, batched specimens for shipment, and dispatched on a fixed monthly schedule. The RDI reference lab received specimens, inventoried them into the program freezer bank, and made specimens available to the sponsor on the sponsor’s specimen-pull schedule. No site-initiation visits, no on-site monitoring visits, no per-subject consent forms, no recruitment funnel.

4. Results

Cumulative specimen count crossed 250 by end-July 2023 (the partner’s strongest two-month opening period at +118 in June and +132 in July), 418 by end-December 2023 after a slower August–September 2023 reflecting seasonal testing-volume patterns, and 729 at program close in March 2024 (Fig. 1).

Monthly cadence reflected the partner laboratory’s clinical-testing volume in each period: stronger months in June–July 2023 (+118, +132), early winter (+93, +161 in December and January) and February (+106), with quieter months in late summer / early fall (Aug–Sep 2023 at near zero, +16 in October). The +161 January 2024 peak coincided with elevated clinical Hepatitis A testing volume at the partner; the August–September 2023 quiet period reflected the partner’s seasonal testing pattern, not a program disruption.

The program closed against the protocol-defined specimen target in March 2024 with no contingency partner activation required. Cumulative specimen-availability variability was within the program plan’s tolerance band throughout.

5. Discussion

Three observations bear noting. First, remnant-specimen collection is operationally a different category from recruitment-based collection. The unit of work is not the patient visit but the partner laboratory’s monthly antibody-positive testing volume; the binding constraint is partner testing throughput, not site-network capacity or recruitment-funnel conversion. The two operational frames should not be compared per-subject-cost like-for-like — they answer different sourcing problems with different operational tools.

Second, the single-partner architecture is an operational simplification that comes with concentration risk. A program running through a single partner has no contingency network if that partner’s testing volume falls short. Partner selection has to weight historical testing-volume disclosure heavily against best-case projections, and the program target should be set conservative against the partner’s baseline rather than its best-case month. The +0/+0 August–September 2023 stretch reflects the partner’s seasonal pattern, not a program failure — the program plan accommodated this variability rather than expecting flat monthly cadence.

Third, remnant programs front-load the regulatory and operational documentation work but have minimal per-month overhead thereafter. Master specimen-handling agreement, IRB-exempt determination, de-identification SOP validation, shipment-cadence agreement — all of this work happens in the program’s first 6–8 weeks. Once the cadence is running, monthly overhead is approximately one shipment receive, one inventory pass, one sponsor-handoff communication.

6. Conclusion

Remnant-specimen sourcing through a clinical-laboratory partnership is a different operational frame than recruitment-based collection — not a smaller version of the same problem. A single high-volume clinical-laboratory partner against an antibody-positive eligibility envelope delivered 729 specimens across 9 months without site-initiation visits, on-site monitoring, patient recruitment, or per-subject consent. The same operational frame — single high-volume partner, master specimen-handling agreement, IRB-exempt determination, recurring monthly shipment cadence — transfers to other antibody-marker remnant-specimen collection programs.