Understanding Covid Vaccine Efficacy over Time — Bridging a Gap Between Public Health and Health Care

Understanding Covid Vaccine Efficacy over Time — Bridging a Gap Between Public Health and Health Care

Imagine if for every patient seen in a healthcare facility we could find out what Covid-19 vaccine they received when and what their clinical evaluation revealed. We could then gain near real-time insight into vaccine efficacy, how that efficacy changes over time, how new viral strains alter it, and what viral and host characteristics (including underlying medical conditions) lead to breakthrough infections in immunized humans. Such tracking requires robust linkage between clinical outcomes (including details of clinical interventions and laboratory studies), data on the specific vaccine administered and the date of administration, and information on the status of the pandemic in the relevant geographic area.

This effort is not an act of futuristic vision. Tightly integrated, population-based health care organizations in countries like Israel have directly informed public health policies, such as recommendations for a third, boosting vaccination, on the scale of several million people.1 Unfortunately, these successes accentuate relative shortcomings in the link between public health and healthcare elsewhere. In most high-income countries, vaccinations for public health purposes are recorded in electronic databases – registries. But even when patients’ clinical courses are documented in electronic medical records (EHRs), information about the relationship between a particular vaccine history and an associated clinical course cannot be easily obtained from the health care system.

We are particularly aware of this challenge in our own work in a growing international volunteer consortium (now comprising nine countries and 335 hospitals) that has been steadily analyzing Covid clinical pathways since March 2020 ( We used a variety of analytical and “boots on the ground” data verification and validation techniques to understand the clinical course of Covid in hospitals during the different waves of the pandemic.2 Yet we are all too aware of the existing information gaps between public health and clinical care. Even in countries with universal health identifiers (which the United States does not have), such as France, Singapore, Italy and Germany, the process of integrating vaccination data into health records is fraught and often delayed, despite multiple national e-health initiatives and the European Strategy of the 2018 Commission on the Digital Transformation of Healthcare.

At the same time, several hospital systems, including some in the United States (e.g. Keck Medicine in California)3), have closed this gap by implementing homegrown (or EHR vendor-designed) systems for matching individual clinical records with state or country vaccination registries. The United Kingdom and the Netherlands have been successful nationally.4 While these systems are exceptions, they demonstrate the feasibility of closing this critical gap between public health and clinical care. They also illustrate specific challenges for the United States, where unless patients revisit a hospital for care, records of their immunizations since the last visit, stored in a state registry, are not automatically updated in the EHR.

Wishes for closing the gap between clinical and population health data on covid vaccination.

What can we learn from the hospital systems that have closed the gap between vaccination registries and their patients’ EHRs? As summarized in the tableSeveral factors would enable more health systems and governments to close this gap between public health and clinical care in the near term. None of these desires require innovation in technologies or governance, but they do require the involvement of local clinical leadership in a dialogue with local public health authorities and a commitment to implementing software processes that are much simpler than those used by EHR suppliers or buyers in the field. recent past.

In particular, hospital systems could contact their existing patients to ask them to forward new immunization data (whether it’s images of their immunization record or codified immunization data from increasingly standardized smartphone apps, such as in Massachusetts and California). That way, each hospital would have an authoritative, complete immunization record, including vaccine mixes, tailored to the patient’s clinical history — independent of, but complementary to, the most recent patient visit. Insofar as patients do not participate, adjustments will have to be made in the data.

This proposal is far from a panacea. The bridgeable gap we describe here is only relevant for countries and health care systems where extensive EHR systems have been deployed on a large scale. We also did not discuss additional steps that could be taken to further promote public health, such as exporting clinical data from EHRs to state or national registries. We also haven’t started merging in real time the clinical course data of patients related to vaccination history, across the multiple boundaries that viruses don’t recognize, but the regulations have to. Even more important is the challenging basic logistics of the “last mile” vaccination.5 And we know some experts would argue that systematic nationwide upgrades of health information infrastructure are preferable to a step-by-step patchwork approach targeting specific diseases.

Despite these limitations, we focused on this small gap in the registry and the EHR because it can be easily filled in the short term, has immediate clinical and public health benefits, including addressing the potential second wave of omicron infections that are now emerging in Europe, and can serve as a bridgehead for broader, more ambitious efforts to connect clinical medicine and public health in the future.