Industry Insights: Regulatory wrangles, untangling adverse events, and an end to cholera vaccine shortages

Intranasal adenoviral vaccine protects against H5N1 in rodent models [1] Researchers at Washington Uni­versity School of Medicine in St Louis developed an intranasal H5N1 avian influenza vaccine using a non-replicating adenoviral vector encoding a designed antigen derived from circulating human-infecting strains. In hamsters and mice, the vaccine elicited strong systemic and mucosal immune responses and provided near-complete protection against infection following high-dose viral exposure. Protection was superior to the same formulation delivered intramuscularly and to current seasonal influenza vaccines.

Intranasal adenoviral vaccine protects against H5N1 in rodent models; Preclinical Research. Credit: NIAID.

Moderna and Merck report sustained 5-year benefit for personalized mRNA melanoma vaccine [2] Moderna and Merck & Co. reported that a regimen combining the personalized mRNA cancer vaccine intismeran autogene with pembrolizumab (Keytruda) reduced the risk of relapse or death by 50% over 5 years compared with pembrolizumab alone in patients with melanoma following surgery. The Phase 2 study previously met its primary endpoint, and extended follow-up indicated maintenance of the survival benefit observed at earlier analyses. The vaccine–immunotherapy combination is being further evaluated, with Phase 3 results anticipated later this year. Merck licensed intismeran autogene from Moderna in 2022 in a $250M agreement.

Moderna and Merck report sustained 5-year benefit for personalized mRNA melanoma vaccine; Clinical Trials. Credit: Matthew Hill.

Molecular mechanism underlying vaccine-induced thrombosis after adenoviral COVID-19 vaccination revealed [3]Wang JJ, Schönborn L, Warkentin TE, et al. Adenoviral inciting antigen and somatic hypermutation in VITT. N. Engl. J. Med. 2026; 394(7), 669–683. 

Researchers identified a mutated autoantibody gene in those with vaccine-induced immune thrombocytopenia and thrombosis (VITT), which may cause their B cells to mistake an adenoviral vector protein for platelet factor 4 (PF4), triggering blood clotting. The authors propose that modifying or removing the implicated adenoviral protein could mitigate this rare adverse event while preserving vaccine efficacy.

Phase 2 trial reports safety and efficacy of oral E coli vaccine in infants [4]Hossain MJ, Secka F, Sanyang LC, et al. Efficacy of ETVAX, a vaccine against enterotoxigenic Escherichia coli-positive diarrhoea in Gambian children: a double-blind, randomised, placebo-controlled, phase 2b trial. Lancet Infect. Dis. 2026; S1473–3099(25), 00774-1.

A double-blind, placebo-controlled Phase 2b trial in The Gambia evaluated the oral whole-cell enterotoxigenic Escherichia coli (ETEC) vaccine ETVAX in 4,936 children aged 6–18 months. Participants were randomized 1:1 to receive ETVAX or placebo. No serious vaccine-related adverse events were reported. Vaccine efficacy was 26.6% against moderate-to-severe ETEC-positive diarrhea excluding coinfections with other pathogens. The best efficacy was achieved when dosing began before 9 months of age.

Novel oral polio vaccine receives WHO prequalification [5] WHO prequalified novel oral polio vaccine type 2 (nOPV2) in February 2026, expanding global supply for responding to circulating vaccine-derived poliovirus type 2 (cVDPV2) outbreaks. The vaccine, manufactured by Biological E. Ltd, India, is designed to be more genetically stable than current oral polio vaccine type 2, reducing the risk of seeding new outbreaks while maintaining effectiveness in interrupting transmission. It is authorized for emergency use in outbreak settings and has been deployed in multiple countries.

Novel oral polio vaccine receives WHO prequalification; Regulation and Policy. Credit: UNICEF Ethiopia/2013/Sewunet.

US FDA changes course on Moderna’s mRNA influenza vaccine [6]Moderna. Moderna announces the US Food and Drug Administration will initiate the review of its investigational seasonal influenza vaccine submission. Feb 18, 2026.

The FDA has agreed to review Moderna’s investigational mRNA influenza vaccine, just a week after issuing a refusal-to-file letter. The dispute centered on the absence of a comparator specifically recommended for adults aged 65 years and older in Moderna’s Phase 3 clinical trial. Moderna stated that the study design had been previously agreed and that additional data from a separate trial using a high-dose comparator were provided. After a meeting between the company and FDA officials, a revised application was accepted, seeking full approval for adults aged 50–64 years and accelerated approval for those aged 65 years and older. A decision is due by August 5.

Valneva voluntarily withdraws chikungunya vaccine from US market following FDA suspension [7] Valneva voluntarily withdrew its biologics license application for Ixchiq following an FDA marketing suspension and a clinical hold on its development program. The suspension, announced in August, followed reports of one death from encephalitis considered directly attributable to the vaccine and more than 20 serious adverse events consistent with chikungunya-like illness. Valneva stated the withdrawal is permanent but intends to continue planned post-marketing studies and engagement with regulators in other regions where the vaccine remains licensed.

Valneva voluntarily withdraws chikungunya vaccine from US market following FDA suspension; Regulation and Policy. Credit: (flickr.com).

Global oral cholera vaccine shortage ends [8]Gavi. Preventive cholera vaccination resumes as global supply reaches critical milestone. Feb 4, 2026. 

Gavi, UNICEF, and WHO have announced that global supply of oral cholera vaccine has increased sufficiently to resume preventive vaccination campaigns after a 3-year suspension. Annual oral cholera vaccine production doubled from 35 million doses in 2022 to nearly 70 million in 2025, with EUBiologics currently the sole large-scale manufacturer.

Charlotte Barker, Commissioning Editor of Vaccine Insights, has over 20 years of experience as a science writer and editor. As Editor of Vaccine Insights, she works with leading scientists to produce review, commentary, research, and multimedia content covering all aspects of vaccine R&D and manufacturing. Previously, Charlotte held senior editorial roles at Texere Publishing (now Conexiant) and Future Science Group, where she directed content strategy, managed editorial teams, and led high-profile editorial projects.

References

1. Ying B, Pyles K, Darling TL, et al. An intranasal adenoviral-vectored vaccine protects against highly pathogenic avian influenza H5N1 in naïve and antigen-experienced animals. Cell Rep. Med. 2026; 7(2), 102582.

2. Moderna. Moderna & Merck announce 5-year data for intismeran autogene in combination with KEYTRUDA(R) (pembrolizumab) demonstrated sustained improvement in the primary endpoint of recurrence-free survival in patients with high-risk stage III/IV melanoma following complete resection. Jan 20, 2026.

3. Wang JJ, Schönborn L, Warkentin TE, et al. Adenoviral inciting antigen and somatic hypermutation in VITT. N. Engl. J. Med. 2026; 394(7), 669–683.

4. Hossain MJ, Secka F, Sanyang LC, et al. Efficacy of ETVAX, a vaccine against enterotoxigenic Escherichia coli-positive diarrhoea in Gambian children: a double-blind, randomised, placebo-controlled, phase 2b trial. Lancet Infect. Dis. 2026; S1473–3099(25), 00774-1.

5. WHO. WHO prequalifies an additional novel oral polio vaccine, strengthening global outbreak response. Feb 13, 2026.

6. Moderna. Moderna announces the US Food and Drug Administration will initiate the review of its investigational seasonal influenza vaccine submission. Feb 18, 2026.

7. Valneva. Valneva provides update on chikungunya vaccine IXCHIQ^®. Jan 19, 2026.

8. Gavi. Preventive cholera vaccination resumes as global supply reaches critical milestone. Feb 4, 2026.