Decoding Rx Attribution with Crossix and IQVIA

The challenge

Vaccine and seasonal brands live and die by their launch window. For a Sanofi respiratory vaccine program, that window was measured in weeks, not months, the relevant prescribing season opened fast, competitive noise was loud from day one, and every dollar had to find the right physician before the moment passed.

Three problems compounded the time pressure. First, the brand needed to prove that media exposure drove actual scripts, not just awareness. Brand leadership had grown skeptical of impression volume as a success metric, and rightly so: a campaign that reaches a million HCPs who never prescribe tells you nothing about whether the media worked. The business question was stark, did programmatic cause physicians to write?

Second, HCP precision was non-negotiable. The target audience was a defined specialty cohort, pediatricians and family medicine physicians with the specific prescribing profile and patient panel most likely to adopt the brand. Spray-and-pray reach against a broad NPI universe would waste budget and contaminate the measurement signal.

Third, compliance and medical-legal-regulatory (MLR) constraints shaped every creative and targeting decision. Audience segments could not be built on inferred patient health status. Creative had to carry the full fair balance payload. Any data partner in the workflow needed documented HIPAA-aligned data practices. On a short timeline, those constraints are a forcing function: you have to design correctly the first time, because there is no room to rebuild mid-flight.

The approach

Measurement came first, not last. Before a single impression was purchased, the Crossix attribution framework was scoped, approved, and wired into the media plan. That sequencing matters more than most teams realize. Attribution set up after a campaign launches cannot control for pre-existing prescribing trends; it can only observe what happened, not prove causation. By establishing test and control HCP cohorts before launch, matched on specialty, geography, and historical prescribing volume, the measurement design could isolate the incremental effect of the media itself.

IQVIA provided the foundational NPI target list, drawing on prescribing data to identify physicians most likely to be persuadable: active in the relevant specialty, with patient panels of the right size and age composition, but not yet brand loyalists. That list became the precision spine of every activation. For a deeper look at the list-building methodology, see Mastering HCP Targeting Best Practices.

The channel mix was built around two objectives: reach every target HCP with enough frequency to register, and extend that reach into environments where physicians spend time outside endemic medical content. Endemic inventory, point-of-care and clinical reference publishers, carried the dense clinical messaging. YouTube and connected TV extended frequency in lean-back moments, reaching the same NPI-matched physicians across screens. This was among the first HCP-targeted YouTube activations the brand had run, requiring close collaboration with Google to validate the targeting methodology. That partnership ultimately earned a $60K Google co-investment credit, a direct consequence of being first to market with the format.

Weekly Crossix readouts drove in-flight optimization. Rather than waiting for an end-of-campaign report, the team monitored in-target reach rate and early conversion signals on a rolling basis, shifting budget toward endemic placements when conversion velocity indicated higher receptivity among that segment, and pulling back on open-web placements where reach was duplicating without adding net-new HCPs. The full measurement and optimization approach is documented in the Pharma Programmatic Measurement Framework.

The results

When the campaign closed and the Crossix attribution report was finalized, three numbers anchored the brand review:

The 1.25% Crossix conversion rate, HCPs exposed to the media who subsequently wrote a prescription within the measurement window, ran at 2.3 times the benchmark for comparable vaccine programs. That ratio matters because it frames the efficiency story: the program did not just convert, it converted at roughly twice the rate a similar investment would typically produce.

The visit-to-Rx figure tells a different story. Of the physicians who had an eligible patient encounter after media exposure, 31.5% converted that visit into a prescription for the brand. That metric is meaningful because it isolates physician intent at the moment of clinical decision. A physician who sees the media, has the right patient in the chair, and writes the script is demonstrating that the media shaped their consideration set, not just their awareness.

Together, the two metrics built the business case for reinvestment. Brand leadership approved a $2.1M incremental budget commitment for subsequent seasonal windows, tied directly to the Crossix evidence. The YouTube first-to-market distinction, supported by the Google co-investment credit, also created a proof point for extending HCP video strategy across other brands in the portfolio.

What I’d take to the next brand

Measurement-first is not a preference, it is a methodology. The single decision that made everything else possible was scoping the Crossix framework before the buy. Teams that treat attribution as a post-mortem activity collect interesting data; teams that treat it as a planning input make better decisions in real time. The weekly optimization cadence on this program was only possible because the measurement infrastructure was already live when the first impressions served.

Visit-to-Rx beats vanity metrics at every budget conversation. Impressions tell a planner whether media ran. CTR tells a planner whether a physician tapped a banner. Visit-to-Rx tells a brand team whether the media influenced a clinical decision. Those are different conversations, and the last one is the only one that generates reinvestment. Building to that metric from the outset, choosing measurement partners, control group design, and reporting cadence to surface it, is what separates a media execution from a business result.

Channel innovation earns partnership dividends. The YouTube HCP activation was operationally complex and required legal review of the targeting methodology. It would have been easier to stay in endemic-only inventory. The co-investment credit and the portfolio-level proof point were the return on that complexity. In pharma, first-to-market on a channel often comes with structural advantages that compound over multiple campaigns. The Pharma Programmatic Advertising Guide covers the channel landscape in more detail for teams evaluating where to push next.

Precision and reach are not a tradeoff, they are a sequence. Deterministic NPI targeting ensured that every dollar was chasing a physician who could actually write the script. Endemic inventory locked in that precision at the point of care. YouTube and CTV then extended frequency among the same verified HCPs in non-clinical environments. The sequencing, precision first, reach extension second, prevented the dilution that happens when broad open-web inventory is added too early in the plan.