Infectious disease is widely regarded by public-health authorities as one of the largest sources of global disease burden, spanning bacterial, viral, and fungal pathogens, and antimicrobial resistance is commonly described as a slow-moving crisis layered on top of it. Even so, new antibiotics have been among the hardest assets in biopharma to finance, because stewardship keeps volumes low and pricing has not historically reflected societal value, a dynamic often summarized as a broken pull incentive next to a comparatively better-funded push incentive. Vaccines sit at the opposite end: mRNA and viral-vector platforms showed during the COVID-19 pandemic that development timelines can compress meaningfully under emergency funding, parallel trial designs, and rolling regulatory review, though that compression relied on conditions that do not exist for most programs. Diagnostics, especially point-of-care and sequencing-based pathogen identification, are increasingly where Sonnerie sees the most fundable pre-seed and seed opportunities, because they can support antibiotic stewardship, offer clearer reimbursement pathways, and de-risk downstream therapeutic decisions. As a pre-seed, seed, and often first institutional check into university spinouts, Sonnerie evaluates infectious disease opportunities with particular attention to reimbursement pathway and non-dilutive funding alignment before committing capital. This is a general discussion of category dynamics and is not investment advice.
What does “infectious disease” mean as an investment category?
Infectious disease as a venture category spans therapeutics and tools built against three broad classes of pathogen: bacteria, viruses, and fungi, along with parasites in a smaller but real slice of global burden. Public-health data has long shown that infectious pathogens remain among the leading causes of death and disability worldwide, with lower respiratory infections, diarrheal disease, tuberculosis, HIV, and malaria representing a persistent baseline burden that predates any single outbreak, and with viral respiratory illness, bacterial sepsis, and invasive fungal infection in immunocompromised patients adding further weight.
What makes the category distinct from most of biopharma is that the pathogen, not just the patient, is a moving target. Bacteria and fungi evolve resistance mechanisms in response to drug exposure, viruses mutate at rates that can outpace a single vaccine formulation, and diagnostic assays can lose sensitivity as a pathogen’s genome drifts. A useful working definition for founders and investors: infectious disease investing means underwriting biology that is adversarial and time-varying, not static, which has direct implications for how a company should be built and financed.
Why has the antibiotic market historically been commercially challenged?
Antimicrobial resistance, or AMR, describes the process by which bacteria, fungi, and other microbes evolve to survive drugs that once killed them. It is widely characterized by public-health authorities as a gradual, compounding problem rather than a single acute event, driven by antibiotic overuse in medicine and agriculture, incomplete treatment courses, and the basic evolutionary pressure that any antimicrobial exerts on the organisms it targets. The clinical consequence is that infections once considered routine can become difficult or impossible to treat with existing drugs.
Despite this urgency, new antibiotic development has been one of the weakest areas of biopharma commercially, and the reason is structural rather than scientific. Health economists and public-health bodies typically describe this as a mismatch between push incentives and pull incentives. Push incentives fund the cost of discovery and early development, through grants, milestone-based nonprofit funding, and public research support. Pull incentives are meant to reward a company after a drug reaches the market, through sales volume and price. In antibiotics, the pull side is broken: a genuinely novel, last-resort antibiotic is deliberately used sparingly by physicians and hospital stewardship programs specifically to delay resistance from developing against it, which means the very clinical success a new antibiotic is designed for suppresses the volume a company needs to earn a return. Antibiotics are also typically short courses of therapy rather than chronic-use drugs, and many health systems and insurers still price them closer to older generics than to the cost of developing a genuinely new class. Several antibiotic developers that won FDA approval for a novel agent in the past decade or so have subsequently filed for bankruptcy or been sold for a fraction of the capital invested in them, a pattern widely discussed across the sector as evidence that approval alone does not solve the commercial problem.
What role do nonprofit and public funders play in early antibiotic development?
Because private capital has been reluctant to fund antibiotic discovery through to approval, a distinct funding ecosystem of public and philanthropic entities has grown up specifically to fill the push-incentive gap. Public agencies focused on biodefense and pandemic preparedness, nonprofit accelerators built around public-private partnership models, and global health-focused product development partnerships all provide milestone-based non-dilutive funding to antibacterial and antifungal programs, often starting at the discovery or preclinical stage. This funding is typically structured as grants or contracts rather than equity, which matters enormously for a pre-seed company because it can extend runway and validate a program without diluting the cap table.
For a university spinout in this space, alignment with these funders early is often a better signal of fundability than a term sheet from a generalist biotech investor. A team that has already secured, or is actively pursuing, non-dilutive support from a recognized push funder is demonstrating both scientific credibility, since these funders run their own technical diligence, and an understanding of how the category’s capital stack actually works. Sonnerie treats this as a meaningful, if not sufficient, positive signal in early diligence on antibacterial and antifungal assets.
How do traditional, mRNA, and viral-vector vaccines actually differ?
Vaccines work by presenting the immune system with a piece of a pathogen, or instructions to build one, so that the body develops memory before a real infection occurs. Traditional platforms include live-attenuated vaccines, which use a weakened but still-replicating version of the pathogen, inactivated vaccines, which use a killed pathogen or its components, and protein subunit vaccines, which use a purified piece of the pathogen, often a surface protein, sometimes paired with an adjuvant to boost the immune response. These platforms have long track records and well-understood manufacturing, but each new vaccine against each new target has historically required its own bespoke development and manufacturing process, which is part of why development has traditionally taken many years.
mRNA vaccines instead deliver a synthetic messenger RNA sequence, packaged in a lipid nanoparticle, that instructs the recipient’s own cells to transiently produce the target antigen, most often a viral surface protein, which the immune system then learns to recognize. Viral-vector vaccines use a harmless or disabled virus as a delivery shell to carry genetic instructions for the target antigen into cells. Both approaches share an important commercial and scientific advantage over older platforms: the manufacturing process is largely pathogen-agnostic, so a platform validated against one target can, in principle, be redirected to a new pathogen or a new variant faster than a traditional vaccine could be redeveloped from scratch, because the change is mainly in the genetic sequence being carried, not the entire production process.
What did the accelerated COVID-19 vaccine effort actually teach about development timelines?
The compressed timeline from pathogen identification to authorized vaccines during the COVID-19 pandemic is often cited as proof that vaccine development can move far faster than the historical norm. That is broadly true, but the more precise and more useful lesson for investors is what specifically enabled the compression, because those enabling conditions were unusual and are unlikely to repeat for most future programs. Clinical trial phases that are normally run sequentially were run with substantial overlap, using adaptive trial designs. Manufacturing capacity was built and scaled at industrial risk before trials had fully read out, funded by public and philanthropic capital willing to absorb the loss if a candidate failed. Regulators, including the FDA and its counterparts abroad, supported rolling submission of data as it accumulated rather than waiting for a single completed application package, then authorized the vaccines on an emergency basis once at least one completed phase 3 trial met its pre-specified efficacy criteria. And critically, the mRNA and viral-vector platforms involved were not started from zero, they built on years of prior academic and biodefense-funded platform research into related pathogens.
The lesson for founders and investors is not that infectious disease development timelines have permanently shortened. It is that platform technologies validated in one program can be redeployed faster against adjacent targets, and that at-risk capital deployed in parallel with clinical development, rather than sequentially after it, is what actually buys speed. Post-authorization safety monitoring for these vaccines also continued well beyond the initial authorization, a reminder that speed to authorization and the full safety evidence base are not the same milestone, and that pharmacovigilance remains an ongoing part of the product lifecycle rather than a box checked at launch.
What role do diagnostics play in the infectious disease investment thesis?
Diagnostics are frequently underweighted relative to therapeutics in how founders and generalist investors think about infectious disease, which is a mistake given both the clinical need and the more tractable commercial path. Two categories matter most. Rapid point-of-care testing brings pathogen identification, and increasingly resistance-marker detection, to the bedside or the clinic in minutes to hours rather than the day or more a send-out culture requires, using formats such as lateral-flow immunoassays or compact molecular, PCR-based, cartridges. Sequencing-based pathogen identification, including metagenomic and next-generation sequencing approaches, allows for pathogen-agnostic detection, identifying an organism, or characterizing its resistance genes, without needing to guess which specific test to order in advance, which is particularly valuable in severe or unusual infections where empiric treatment is otherwise a guess.
The strategic value of better diagnostics extends beyond the immediate clinical benefit to the patient. Rapid, accurate identification of the causative organism and its resistance profile is one of the few tools that can genuinely narrow the gap between a novel antibiotic’s clinical importance and its usage volume, by letting physicians confidently target the right drug to the right patient rather than defaulting to broad-spectrum agents. In other words, diagnostics can help repair, at the margins, the very pull-incentive problem that makes standalone antibiotic development so hard to finance, which is one reason Sonnerie views diagnostics and therapeutics in this category as complementary rather than competing places to deploy capital.
What does a fundable pre-seed infectious-disease spinout look like?
Sonnerie backs university spinouts at the earliest institutional stage, so the question is not whether a program is a good idea in the abstract, it is whether the specific combination of science, team, and capital plan can survive the category’s known failure modes. A handful of characteristics consistently distinguish a fundable pre-seed infectious-disease company.
First, founder-operator fit: a technical founder, often a principal investigator or a former lab member, paired with or evolving toward operating leadership that has actually taken a regulated product through at least one prior stage-gate, whether that is an IND filing, an FDA clearance or approval, or a CLIA-validated laboratory test launch. Second, a realistic view of the reimbursement pathway before the first dollar of institutional capital is raised, not after: a diagnostics or platform company should be able to articulate, even at a basic level, who pays and under what billing code or coverage pathway, and a therapeutics company in the antimicrobial space should be able to name the specific push funders whose criteria it fits. Third, capital efficiency to the next inflection point: because infectious-disease programs, especially antimicrobials, cannot assume a large future pull-side reward, the milestones between pre-seed and the next round need to be achievable on a lean budget, ideally with non-dilutive funding covering a meaningful share of the burn. Fourth, platform or optionality value: a technology that can plausibly address more than one pathogen or more than one clinical setting is more resilient to the category’s specific commercial risks than a single-asset bet.
How does Sonnerie evaluate infectious disease given its unusual reimbursement dynamics?
Sonnerie’s approach to this category starts from the premise that scientific merit and financeability are separate questions that both need to clear the bar. On the science side, we look for de-risked biology, meaning mechanistic rationale supported by data generated in the academic lab, ideally with some independent replication, and a clear articulation of what could kill the program, such as a resistance mechanism that already exists in the wild, a manufacturing bottleneck, or an immunogenicity risk, rather than a pitch that elides those risks.
On the financeability side, we weight the category’s structural reimbursement dynamics explicitly rather than treating infectious disease as ordinary biopharma. That means diagnostics, sequencing-based pathogen identification, and platform technologies with multiple potential pathogen targets tend to screen better for us at the earliest stage than a single novel antibiotic asset with no de-risked path to a pull mechanism, because the commercial pathway is more conventional and easier to underwrite with seed-stage capital. Where we do look at antimicrobial therapeutics directly, we pay close attention to whether the company has already secured, or is well positioned to secure, non-dilutive push funding, and whether management understands the difference between an approval event and a commercially sustainable product, given how often those two have diverged historically in this space. Vaccine-adjacent opportunities are evaluated partly on platform reusability, since a technology that could in principle be redirected across pathogens carries more optionality value than one built for a single indication. Across all of it, our role as a first institutional check is to help operator-led teams build the capital plan and regulatory sequencing around the science from day one, rather than discovering the reimbursement problem only after the science has already worked. This reflects our general approach to the category and should not be read as investment advice regarding any specific company or technology.
Frequently asked questions
Why is antimicrobial resistance considered a market failure rather than just a public-health problem?
Because the incentives that normally reward a successful drug do not hold for antibiotics. A genuinely novel, effective antibiotic is deliberately used sparingly by stewardship programs to preserve its usefulness against resistance, which suppresses the sales volume a company needs to recoup development costs, even when the drug is clinically valuable.
What is the difference between push and pull incentives in antibiotic development?
Push incentives fund the cost of research and development directly, through grants, milestone funding, and public or philanthropic support, largely before or independent of commercial sales. Pull incentives are meant to reward a company after approval through market sales. In antibiotics, push funding from nonprofit and public bodies has been comparatively active, while pull-side rewards have remained weak because of low prescribing volumes and pricing that often does not reflect societal value.
Are mRNA and viral-vector vaccines only relevant to pandemic pathogens?
No. Both platforms are pathogen-agnostic in their manufacturing approach, meaning the same underlying production process can, in principle, be redirected toward a new target antigen by changing the genetic sequence being delivered. This makes them relevant well beyond any single outbreak, including for pathogens with existing but imperfect vaccines and for pathogens that mutate quickly.
Can a pre-seed antibiotic company realistically get funded today?
It is possible but requires a specific structure: alignment with non-dilutive push funders, a capital-efficient plan to the next milestone, and ideally platform or multi-target optionality rather than a single asset with no clear route to a sustainable pull mechanism after approval.
How do rapid diagnostics help address antimicrobial resistance?
By identifying the causative pathogen and its resistance profile quickly, rapid diagnostics let clinicians prescribe a narrow, targeted antibiotic instead of defaulting to broad-spectrum treatment. That narrower use pattern is one of the few practical levers that can increase appropriate volume for a novel antibiotic while still supporting stewardship goals.
What did COVID-19 vaccine development really change about typical timelines?
It showed that running trial phases with substantial overlap, manufacturing at risk before efficacy data was final, and using rolling regulatory review can meaningfully compress timelines, but those conditions depended on emergency-level funding and platforms that had already been validated in prior research. It is not evidence that ordinary vaccine or drug timelines have permanently shortened.