From Valency To Vaccine Design: The Changing Competitive Landscape In Pneumococcal Vaccines

By Pooja Goyal, Engagement Manager; Eu Shen Seow, Senior Business Analyst; and Yushi Redhead, Consultant, Lifescience Dynamics

Streptococcus pneumoniae remains one of the leading bacterial pathogens responsible for invasive pneumococcal disease (IPD), pneumonia, acute otitis media (AOM), sinusitis, and meningitis, particularly in young children, older adults, and immunocompromised individuals. Although widespread vaccination has substantially reduced disease burden, the organism's genetic diversity and ability to adapt under vaccine pressure continue to drive an active innovation landscape.

Current CDC recommendations prioritize pneumococcal vaccination for all children younger than 5 years of age and for adults aged 50 years and older and those 19 to 49 years with specific risk conditions. Routine pediatric immunization provides direct protection while also reducing nasopharyngeal carriage, generating herd immunity that has historically lowered disease incidence in unvaccinated older adults. However, this indirect protection is increasingly being challenged as non-vaccine serotypes emerge.

Pneumococcal vaccine development has evolved from 23-valent polysaccharide vaccines (PPSV23) (that provided broad serotype coverage but limited immune memory) to protein-conjugated vaccines (PCVs) that induce T-cell dependent responses and durable immunological memory. Beginning with PCV7 and subsequently PCV10 and PCV13, manufacturers have steadily increased serotype coverage, culminating in approved higher-valency vaccines, such as Vaxneuvance (PCV15), Prevnar 20 (PCV20), and CAPVAXIVE (PCV21). This progression reflects an industry-wide strategy to maintain relevance against shifting epidemiology while preserving immunogenicity against disease-relevant serotypes.

Why Unmet Need Persists Despite Higher-Valency PCVs

Despite major public health success, important challenges remain. Serotype replacement is the dominant biological limitation. Elimination of vaccine-covered serotypes creates space for previously uncommon serotypes to expand, thus requiring continuous surveillance and periodic reformulation. Consequently, increasing valency has become the principal competitive strategy among vaccine developers.

However, expanding valency introduces immunogenicity creep: the difficulty of maintaining robust immune responses across an increasing number of polysaccharide antigens within a single formulation, while maintaining an acceptable tolerability profile. Developers must carefully balance broader coverage against manufacturing complexity and preservation of functional antibody responses.

Serotype 3: The Benchmark Challenge For Next-Generation Vaccines

Serotype 3 has emerged as an example of why the next phase of PCV innovation cannot rely on valency alone. Although serotype 3 is included in multiple licensed PCVs, it continues to contribute meaningfully to residual IPD and complicated pneumonia. Its biology makes it particularly difficult to control.

As a result, manufacturers are not only focusing on covering serotype 3 in their vaccines but also assessing whether their platforms can generate strong functional immune responses against it. Public company communications from several manufacturers now emphasize improved serotype 3 immunogenicity as a key differentiator, particularly as the market becomes more crowded with higher-valency candidates. Pfizer, for example, has highlighted strong immune responses for its next-generation 25-valent candidate, including differentiated performance against serotype 3 compared with PREVNAR 20, in early pediatric development. Vaxcyte has similarly positioned its site-specific conjugation platform as a way to support broad coverage while maintaining immune quality across serotypes.

This focus is important for the competitive landscape, both commercially as well as scientifically, because a product that demonstrates both broader coverage and superior functional immunogenicity against serotype 3 could establish a meaningful competitive advantage in both pediatric and adult markets.

Serotype 4: A Reminder That Epidemiology Matters As Much As Composition

Serotype 4 illustrates a different type of unmet need. Unlike serotype 3, the problem is not primarily poor vaccine inclusion or associated protection, as serotype 4 has been included in several PCVs, with immune response generation having been demonstrated. Instead, recent surveillance has shown that residual disease can concentrate in populations that are not cleanly addressed by standard vaccination schedules. CDC-linked analyses have documented increases and clusters of serotype 4 IPD among younger adults (i.e., less than 65 years old), often experiencing homelessness along with other risk factors (e.g., alcoholism, smoking, injectable recreational drug use), suggesting that persistent reservoirs may reflect gaps in vaccine access, uptake, and adult immunization strategy.

For manufacturers and public health stakeholders, serotype 4 reinforces the importance of life-course vaccination and targeted adult strategies. It also highlights why epidemiology-driven vaccine design can be a meaningful differentiator. A vaccine that covers serotypes responsible for a larger share of adult IPD may have a clearer value proposition in older adults and risk-based populations, provided uptake strategies reach those most likely to benefit.

The Competitive Race: From Valency To Vaccine Engineering

The current market can be viewed as a transition from a first-generation “coverage race” to a next-generation “coverage plus quality” race. Pfizer’s PREVNAR franchise remains anchored in the CRM197 carrier-protein platform. PREVNAR 20 expanded on PCV13 by adding seven serotypes, with Pfizer’s 25- and 35-valent clinical programs now signaling continued investment in broadening the pediatric and adult franchises, respectively, while attempting to strengthen responses to clinically important serotypes.

Merck’s VAXNEUVANCE (PCV15) added incremental pediatric and adult coverage, while CAPVAXIVE (PCV21) was designed specifically around adult epidemiology. Merck has emphasized that CAPVAXIVE covers serotypes responsible for a greater proportion of adult IPD than PCV20, positioning it as an adult-optimized vaccine. This strategy reflects a broader shift toward matching vaccine composition to the disease burden of specific populations.

Vaxcyte’s cell-free protein synthesis platform and site-specific conjugation chemistry are designed to enable very high-valency vaccines while preserving consistency and immune quality. VAX-24 and VAX-31 have been positioned as potential best-in-class candidates. Though pivotal clinical trial results are still awaited, VAX-31 aims to cover a very broad share of circulating adult disease while maintaining functional immune responses across shared and incremental serotypes.

Inventprise represents another important development direction. Its IVT PCV-25 program, in development for pediatric and adult populations, uses a proprietary PEG-linker conjugation platform. Serotypes are also chosen for particular relevance to lower- and middle-income countries (LMICs). The company has described this approach as a way to improve conjugation efficiency and support broad serotype coverage, with a particular focus on serotypes relevant to global pediatric disease. This makes Inventprise especially relevant to the question of how next-generation PCVs may be adapted for LMICs, where affordability, supply, and local serotype epidemiology are critical.

GSK and Sanofi remain key competitors in the space because of their broader vaccine manufacturing, carrier-protein, and respiratory vaccine capabilities. Both companies have the platform expertise and global infrastructure to influence future development.

The competitive landscape is also expanding beyond the traditional focus on infants and older adults. Merck recently received FDA approval for an additional indication for CAPVAXIVE in children and adolescents aged 2 through 17 years who are at increased risk for pneumococcal disease. The approval was based on the Phase 3 STRIDE-13 trial and represents a broader life-course approach for a vaccine initially designed around adult disease epidemiology.

In addition, Pfizer’s PREVNAR 20 and PREVNAR 13 FDA labels include vulnerable adolescents up to 17 years old, reflecting a wider recognition of vaccination need outside of young children and older adults.

Future Outlook

Pneumococcal vaccination remains one of the strongest success stories in bacterial disease prevention, but the residual burden is now posing new challenges. Serotype replacement; the stubborn biology of serotype 3; concentrated adult reservoirs, such as serotype; and the complexity of adult vaccine uptake all suggest that the next advance will need to be smarter and broader. The future competitive landscape will likely be defined by vaccines that combine expanded serotype coverage with preserved or improved functional immunogenicity, particularly against difficult serotypes.

While the emergence of serotype 4 in populations outside the usual vaccination recommendations is recognized, this is more likely to be addressed by regional and local-level direct public health interventions, rather than changes to national-level immunization schedules. With existing vaccines shown to generate serotype specific immune responses, the challenge is largely better characterized by the need to drive uptake in a previously underrecognized vulnerable population, rather than clinically unmet need. Indeed, examples of such campaigns in the western U.S., including Alaska and Colorado, have shown the effectiveness of targeting specific vulnerable population/s with existing PCVs.

Companies capable of demonstrating stronger responses to serotype 3, credible adult and pediatric life cycle strategies, scalable manufacturing, and some movement toward serotype-independent protection will be best positioned to shape the next era of pneumococcal disease prevention.

About The Authors

Pooja Goyal is an engagement manager based out of Lifescience Dynamics’ Toronto office. She has over 10 years of experience in the pharmaceutical consulting industry. Pooja brings expertise in competitive intelligence, opportunity assessment, market access and pricing, and disease area strategy projects across therapy areas. During the early part of her career, she also worked in the analytical R&D of a leading ophthalmic manufacturing firm. Pooja holds an MS (Pharm) in Medicinal Chemistry from National Institute of Pharmaceutical Education and Research (NIPER), Mohali, India, and a Bachelor in Pharmaceutical Science from Panjab University, Chandigarh, India.

Eu Shen Seow, Ph.D., is a senior business analyst at Lifescience Dynamics with a doctorate in infectious diseases immunology, investigating host pentraxin interactions with Leishmania promastigote glycosylated products and the potential downstream immunomodulatory effects. He has supported clients over a wide range of therapeutic areas, with a focus on immunology and rare diseases, and has over three years of experience in the competitive intelligence and market research fields.

Yushi Redhead is a consultant at Lifescience Dynamics with a diverse research background in both academic and industry settings. He has extensive experience in conducting CI and primary research across a wide range of indications, including infectious diseases (COVID, RSV, influenza), oncology, and women’s health. Yushi has a Ph.D. in developmental biology from King’s College London/The Francis Crick Institute, an MSc in clinical neuroscience from University College London, and a BSc in biochemistry from Swansea University.