Research Evidence / Overview of Studies for Ekam
Evidence for Use in Smallpox Prevention (Primary Indication)
Because the smallpox virus has been eradicated globally, research demonstrating the prevention provided by Ekam against the actual disease could not be conducted in humans. Instead, the evidence relies on Randomized Controlled Trials (RCTs) that compared Ekam to the previous smallpox vaccine, which served as a reference vaccine.
These studies were evaluated in healthy adults, including those who had never been vaccinated against smallpox (primary vaccination) and those who had been vaccinated previously (revaccination). Researchers used a surrogate endpoint to assess the vaccine's function. The main measure was the Major Cutaneous Reaction, which is the appearance of a specific localized skin lesion at the vaccination site that served as the primary surrogate endpoint in the trials. They also monitored Neutralizing Antibody Titers, which measure the level of antibodies in the blood that can neutralize the virus.
Trials reported the measurement of the Major Cutaneous Reaction in people who received Ekam; these measurements were compared to the reported outcomes for the reference vaccine. Studies monitored the antibody responses (immunogenicity) in Ekam recipients and reported these measurements against the reference range of the predecessor vaccine. This evidence contributes to the broader evidence landscape regarding the measured immune patterns. However, because effectiveness is inferred from this surrogate endpoint and comparative immunogenicity, rather than direct human evidence against the Variola virus, the evidence remains limited to this specific mechanism of action.
Evidence for Use in Mpox Prevention (Cross-Protection)
Ekam has been evaluated in research exploring the prevention of mpox (monkeypox) disease. This research is based on the biological fact that both smallpox and mpox are caused by similar viruses (Orthopoxviruses), suggesting that the immunity developed against one may provide cross-protection against the other.
Dedicated randomized controlled trials (RCTs) against naturally occurring mpox have not been conducted. Research has primarily involved Retrospective Observational Studies, which examined data from high-risk populations during mpox outbreaks, and Systematic Reviews of the existing data. Animal challenge studies were also used in research exploring protection against the mpox virus.
Research examined outcomes related to the incidence of mpox disease in observational settings, comparing individuals with and without prior vaccination. Studies also monitored cross-reactive antibody measurements, and data suggest patterns related to immune responses that may overlap between the viruses. However, because this evidence relies heavily on observational data and inference, certainty remains low, and the evidence quality varies across studies.
Durability of Protection: Long-Term Studies and Follow-up
Research has also explored the persistence of the immune response generated by Ekam. The initial evaluations focused on short-term outcomes, such as the Major Cutaneous Reaction and antibody titers measured within the first month after vaccination.
Studies monitored recipients over defined time intervals to track changes in the neutralizing antibody levels. Research has explored intermediate to long-term follow-up regarding the durability of the immune response. However, long-term effects are not fully established, and there is limited information for long-term outcomes, making continued surveillance necessary.
Evidence in Specific Populations
The primary clinical evaluations for Ekam were conducted in healthy adults, covering a wide range of ages. These studies included populations who were receiving a smallpox-type vaccine for the first time, as well as those who had received a previous generation vaccine many years before (revaccination).
Research mainly describes patterns observed in these studied groups. Data for certain groups, such as children, pregnant individuals, and people with various underlying comorbid conditions, remain insufficient in the main regulatory studies, and results apply only to the healthy adult populations studied.
Understanding Research Gaps and Uncertainties
Research provides insight into short-term changes and immune responses, but evidence highlights what is known and what is still uncertain. The principal limitation is the inferential nature of the effectiveness against both smallpox and mpox. For smallpox, effectiveness relies on a surrogate endpoint and comparative immunogenicity, not direct proof against the eradicated virus. For mpox, effectiveness is largely inferred from cross-protection, with observational evidence being subject to the limitations of real-world data collection.
Furthermore, studies contribute to the broader evidence landscape, but follow-up durations were limited in the key trials, and data for long-term outcomes are not well characterized.