Vaccines

Vaccines Strategy

Not investment advice. This page is for informational and educational purposes only. Sterling is not a registered investment advisor. Nothing here is a recommendation to buy, sell, or hold any security. Markets carry risk and you may lose money. Do your own research and consult a licensed professional before making any investment, securities purchase, or trading decision.

Thesis

Why this sector matters to investors right now. Structural, not market timing.

Vaccines in 2026 is not an mRNA sector. It is four diversified P&Ls plus a seasonal respiratory fight. Merck vaccines did $10.711 billion in 2025, GSK £9.157 billion, and Sanofi €7.936 billion. Pfizer does not publish a single vaccines line in its top-10 table, but Prevnar family ($6.494 billion) and Comirnaty ($4.367 billion) were its second- and fourth-largest products. Moderna's entire company did $1.94 billion. The investable question is who owns which franchise (HPV, shingles, pneumococcal, RSV, flu, COVID) after the pandemic APA world ended, and whether ACIP and Gavi remain reliable demand switches.

The second-order story is recommendation design and pipeline attrition. Adult RSV did not become an annual shot: ACIP recommends a single dose for adults 75 and older and for 50 to 74 at increased risk. GSK Arexvy did £0.6 billion in 2025. Infant RSV prevention is mostly a monoclonal antibody (Beyfortus €1.781 billion), not a vaccine. Moderna discontinued congenital CMV in October 2025 after a Phase 3 miss (6% to 23% efficacy) and missed norovirus Phase 3 in 2026. Platform M&A is consolidating: BioNTech closed CureVac in December 2025, Sanofi agreed to buy Dynavax for about $2.2 billion. The remaining swing factor on the mRNA names is intismeran autogene with Merck, plus whether mRNA flu can take share from Sanofi and CSL Seqirus.

Structural drivers

Forces that shape long-run demand and economics. Each driver is sourced.
  • •Endemic cash cows still print. Shingrix £3.558 billion in 2025 (+8% CER) with 66% of sales outside the US. Prevnar family $6.494 billion. Sanofi polio/pertussis/Hib €2.554 billion. Source: GSK FY 2025 results; Pfizer 2025 annual review; Sanofi FY 2025 results.
  • •COVID is seasonal, not gone. Comirnaty $4.367 billion in 2025. BioNTech held more than 50% global COVID share in the fall 2025 season. Source: Pfizer 2025 annual review; BioNTech 2025 annual report.
  • •Infant RSV mAbs created a new prevention budget. Beyfortus €1.781 billion (+9.5% CER) in more than 45 countries. Merck clesrovimab (Enflonsia) FDA June 2025. Source: Sanofi FY 2025; Eureka RSV landscape 2026.
  • •IRA Part D $0 cost-sharing for ACIP-recommended adult vaccines is a coverage tailwind for Shingrix, RSV, pneumococcal, and COVID. Source: CMS IRA vaccine cost-sharing materials.
  • •Ex-US Shingrix is the GSK growth engine: France launch, Japan reimbursement from April 2025, China co-promotion. US cumulative immunization 44% (+4 ppt), US sales -17%. Source: GSK FY 2025 results.
  • •mRNA combo respiratory (COVID plus flu) is the platform's remaining commercial path after CMV. mCOMBRIAX EU-approved; mFLUSIVA PDUFA 5 August 2026. Source: Moderna Q2 2026 8-K.
  • •Dose-volume manufacturing in India (Serum Institute ~4 billion doses) keeps Gavi/UNICEF prices in a different universe from US branded. Source: Serum Institute / Bavarian Nordic 11 March 2026 PR.

Structural risks

Forces that could compress demand, change economics, or break the thesis.
  • •ACIP recommendation language can delete a TAM. The 2024 RSV revision (single dose, age 75 plus risk-based younger adults, not annual) is why Arexvy did not become a COVID-scale franchise. Source: CDC MMWR 73(32e1); CDC RSV adult guidance.
  • •US policy tumult around HHS and ACIP in 2025-2026 is already in guidance. Sanofi expects vaccine sales to decline slightly again in 2026. Source: Sanofi FY 2025 results call (FiercePharma, 29 Jan 2026).
  • •Country concentration. Gardasil -39% to $5.233 billion in 2025 on China destocking. One tender market reversed a franchise. Source: Merck Q4 2025 other financial disclosures.
  • •Pipeline attrition on latent viruses. Moderna CMV Phase 3 miss (October 2025) and norovirus Phase 3 miss (2026) cut the non-respiratory mRNA story. Source: Moderna CMV PR 22 Oct 2025; BioSpace norovirus 2026.
  • •Shared fill-finish with GLP-1. Peptide pens and vaccine lots compete for aseptic calendar at Thermo Fisher, Lonza, and in-house plants. Source: Thermo Fisher and Lonza capital-markets materials; GLP-1 sector fill-finish notes.
  • •COVID APA-to-commercial transition. BioNTech guided a modest 2026 Comirnaty decline as Europe leaves multi-year contracts. Source: BioNTech JPM 2026 update.
  • •Adult RSV is not an annual refill. Coverage among 75+ was 40.9% as of January 2026 per CDC RSVVaxView commentary; people already vaccinated should not get another dose under current language. Source: CDC RSV adult guidance.

Competitive landscape

How to think about the players. Framing along axes (pure play vs diversified, incumbent vs challenger, etc). Not stock picking.

Five archetypes, not a ranked list of tickers. (1) Diversified vaccine P&Ls: GSK, Merck, Pfizer, Sanofi. They own Shingrix, Gardasil, Prevnar, Beyfortus, and the pediatric schedules. Compare them on franchise mix and country risk, not on 'vaccine exposure' as a single multiple. (2) mRNA platforms: Moderna and BioNTech. Revenue is still respiratory; option-value is oncology (intismeran, iNeST). BioNTech's 2026 guidance assumes no oncology product revenue. (3) Flu and regional specialists: CSL Seqirus, Takeda, Novavax (now a Sanofi-led commercial residual plus adjuvant IP). (4) Travel and biodefense: Bavarian Nordic, Valneva, Emergent. Outbreak and stockpile buyers, not ACIP adult retail. (5) Volume manufacturers: Serum Institute and Bharat Biotech (private), Zhifei in China. Dose volume, not US net price. Thermo Fisher, West, and Lonza are the supply-chain overlay and are dual-homed with GLP-1.

Key metrics to watch

The operational and financial metrics that matter most in this sector. Each one names its source and update cadence.
MetricSourceFrequencyWhy it matters
Vaccine-segment revenue by issuerGSK, Merck, Sanofi quarterly vaccines lines; Pfizer product table (Prevnar, Comirnaty); Moderna total company revenueQuarterlyThe four P&Ls plus Moderna are the only numbers large enough to move a sector view. Do not substitute consultant TAM.
Shingrix ex-US mix and US immunization rateGSK quarterly vaccines commentaryQuarterlyTests whether the US is done (44% immunized, US sales -17%) while France, Japan, and China still compound.
Gardasil China versus USMerck geographic product tableQuarterlyThe 2025 destock is the sector's country-risk case. US +9% versus China collapse is the split to watch.
Adult RSV doses versus infant mAb salesGSK Arexvy, Pfizer Abrysvo, Moderna mRESVIA; Sanofi Beyfortus; Merck clesrovimabQuarterly in seasonTells you whether RSV is a vaccine market or an antibody market, and whether ACIP's single-dose design is binding.
COVID seasonal share (Comirnaty vs Spikevax vs Nuvaxovid)Pfizer/BioNTech, Moderna, Novavax/Sanofi seasonal updates; CDC COVIDVaxViewSeasonalThe APA world is over. Share and recommendation language now set the cash residual.
ACIP votes (February, June, and strain meetings)CDC ACIP agendas and MMWRPer meetingA recommendation change is a demand switch. RSV 2024 is the template.
Intismeran autogene trial and filing statusModerna and Merck joint releases; ClinicalTrials.govAd hocLargest remaining non-respiratory option on the mRNA names. BioNTech guided no oncology product revenue in 2026, so this is still option-value.

Catalysts and milestones

Known upcoming events that could move the sector. Dated where possible.
  • •Moderna mFLUSIVA FDA decision after the 5 August 2026 PDUFA. VRBPAC was unanimous. Confirm the label before treating flu as a 2026 revenue line. Source: Moderna Q2 2026 8-K.
  • •Intismeran autogene Phase 3 melanoma regulatory path in 2026. Phase 2b five-year data showed a 49% reduction in recurrence or death versus Keytruda alone. Source: Moderna FY 2025 release; Merck/Moderna trial updates.
  • •Sanofi-Dynavax close (announced 24 December 2025, expected Q1 2026). Confirm the 8-K that HEPLISAV-B is inside Sanofi. Source: Sanofi-Dynavax PR.
  • •2026-27 COVID strain (XFG) commercial season, split roughly 50/50 US vs international for Moderna. Source: Moderna Q2 2026.
  • •GSK Arexvy India path after the May 2026 CDSCO SEC positive opinion. Source: Roots Analysis / GSK local disclosure.
  • •EC mRESVIA joint procurement (up to 24 million doses, six countries) as a 2026 international volume print. Source: Moderna Q2 2026 8-K.
  • •Next ACIP RSV discussion of additional doses. Current language is one lifetime dose. A booster recommendation would reopen the adult TAM. Source: CDC RSV adult guidance.

What would change the view

Conditions or evidence that would invalidate the thesis or materially shift the risk picture.
  • •ACIP recommends a second RSV dose or an annual schedule. Adult RSV would look like flu, not like a one-time catch-up.
  • •Gardasil China restocks for two consecutive quarters while US stays positive. The 2025 destock would look like a working-capital event, not a demand event.
  • •Intismeran files and a major regulator accepts the package. mRNA would have a non-respiratory P&L path.
  • •mFLUSIVA is not approved, or is approved into a recommendation that excludes most healthy adults. mRNA flu would stay a pipeline slide.
  • •Sanofi or GSK vaccine sales grow at a mid-single-digit CER rate for two years after the 2025 flattish prints. The 'slight decline' guidance would be a cycle, not a structure.
  • •HHS or ACIP removes or sharply narrows COVID, shingles, or HPV adult recommendations. Coverage and pharmacy traffic would reset.
  • •A second infant RSV mAb (clesrovimab) takes material share from Beyfortus without growing the category. That is a price fight, not a prevention-budget expansion.

What we are not covering

Sub-areas, technologies, or companies we are deliberately excluding from the analysis, and why.
  • •Veterinary vaccines (Zoetis, Merck Animal Health as a P&L line).
  • •RNAi and antisense (Alnylam, Ionis). Nucleic-acid adjacent, not vaccines.
  • •Cell and gene therapy.
  • •Consultant global TAM figures ($65B to $89B for 2025 depending on vendor). Caption-only if used on charts, never in this thesis.
  • •Pfizer Abrysvo 2025 dollar sales. Not in the top-10 performance PDF; pull from the 10-K before quoting a number.
  • •mFLUSIVA as an approved product. PDUFA was 5 August 2026; this review does not treat approval as confirmed.
  • •GLP-1 obesity economics. Dual-homed tickers (PFE, MRK, AZN, TMO, WST) are analyzed there for metabolic drugs.

Sources

Primary sources cited in this analysis. Links open in a new tab.

Audit trail

Record of the last review and what changed. Required on every refresh.
Last reviewed: 2026-08-19
Change log
  • 2026-08-19Initial publication. Thesis, drivers, risks, and metrics sourced from GSK FY 2025 results, Merck Q4 2025 product table, Sanofi FY 2025 vaccines table, Pfizer 2025 annual review, Moderna FY 2025 and Q2 2026 8-K, BioNTech 2025 annual report, CDC ACIP RSV MMWR, and the deal PRs for CureVac and Dynavax.
Unresolved questions
  • •Pfizer Abrysvo 2025 revenue from the 10-K vaccine footnotes.
  • •CSL Seqirus FY 2025 flu revenue in USD (AUD fiscal year offset).
  • •Whether FDA approved mFLUSIVA after the 5 August 2026 PDUFA.
  • •Whether the Sanofi-Dynavax tender closed; confirm 8-K.
  • •Intismeran Phase 3 primary endpoint, hazard ratio, and filing timeline from the companies' joint release rather than secondary press.
  • •Lonza-Moderna current contract mix; do not repeat 2021-2023 capacity headlines.
  • •CDC RSVVaxView latest coverage print versus the January 2026 40.9% figure for adults 75+.
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Vaccines Strategy: Market Data | Sterling