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The leap in influenza vaccine technology: from split-virus vaccines to whole-population subunit vaccines – what are the key advancements in the third-generation vaccines?
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- Time of issue:2026-08-19
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(Summary description)The third-generation influenza vaccine update – what's the advantage of the subunit vaccine?
The leap in influenza vaccine technology: from split-virus vaccines to whole-population subunit vaccines – what are the key advancements in the third-generation vaccines?
(Summary description)The third-generation influenza vaccine update – what's the advantage of the subunit vaccine?
- Categories:Industry news
- Author:
- Origin:
- Time of issue:2026-08-19 10:19
- Views:
The third-generation influenza vaccine update – what's the advantage of the subunit vaccine?
Influenza, also known as the flu, is an acute respiratory infectious disease caused by the influenza virus. Influenza viruses are classified into four types—Type A, Type B, Type C, and Type D—among which the Type A and Type B influenza viruses are primarily responsible for seasonal influenza outbreaks. Currently, the predominant strains circulating among the population include the Type A H1N1 and H3N2 subtypes, as well as the Type B Victoria lineage [1].
The threat posed by influenza is far greater than that of the common cold; its lethality stems not only from the virus itself but also from the severe complications it can trigger. Pneumonia is one of its most common complications; when complicated by a bacterial infection, the mortality rate is three times higher than that of uncomplicated viral influenza infection [2]. Additionally, other complications in children may involve the heart or nervous system, leading to conditions such as myocarditis or encephalitis; individuals of all age groups can experience dehydration or exacerbation of underlying chronic diseases due to influenza [3]. Data indicate that in China, approximately 92,000 excess respiratory system disease-related deaths occur annually as a result of influenza, with an average annual total economic burden reaching RMB 26.381 billion [4]. Given the serious consequences of influenza, the Chinese Center for Disease Control and Prevention recommends that individuals aged 6 months or older who have no contraindications to vaccination should receive the influenza vaccine. Influenza vaccination is considered the most cost-effective and effective measure for preventing influenza, as it significantly reduces the risk of contracting influenza and developing severe complications in vaccinated individuals [1].
With continuous technological advancements, the influenza vaccine has undergone three major technological leaps – from "whole-virus" to "lytic" and then to "subunit" formulations – each representing a distinct phase of technological development.
Three-generation influenza vaccines: three major technological leaps
Whole-virus vaccine: The whole-virus inactivated influenza vaccine is a first-generation influenza vaccine developed in the 1940s; it is composed of intact, non-infectious viral particles. Although this vaccine effectively induces both humoral and cellular immune responses and demonstrates good immunogenicity, it was later replaced by split-virus vaccines due to its higher incidence of adverse reactions [5,6].
Lytic influenza vaccines: These represent a second-generation lytic influenza vaccine formulation in which a lytic agent is used to disrupt the viral envelope structure, breaking down the viral particles into smaller fragments, thereby removing large-molecule proteins and viral nucleic acids while retaining effective surface antigens such as hemagglutinin (HA) and neuraminidase (NA). This approach not only elicits a robust immune response but also results in relatively fewer adverse reactions compared to whole-virus vaccines, due to the removal of certain viral components [7].
Subunit vaccine: As a third-generation influenza vaccine, it builds upon traditional split-virus vaccines through further deep separation and purification, eliminating additional heterogeneous proteins such as viral internal proteins, and extracting only the most critical surface-derived antigens—HA and NA—with significantly improved purity. This approach retains immunogenicity while reducing the potential risk of adverse reactions associated with these heterogeneous proteins [8,9].
The technical advantages and value of the subunit influenza vaccine
The classification of the three categories of vaccines corresponds to three distinct iterations of influenza vaccine technology. The transition from split-virus vaccines to subunit vaccines represents a technological advancement in both "purity" and "safety" manufacturing processes. Subunit vaccines represent the advanced choice within this technological evolution. Among these, the subunit influenza vaccine suitable for the entire population aged 6 months and older has been repeatedly cited in domestic authoritative clinical practice guidelines. In January 2026, the trivalent influenza virus subunit vaccine, independently developed by Ab&B Bio-Tech CO.,LTD.JS, was approved for market launch. Compared to other subunit influenza vaccines indicated for individuals aged 3 years and older, this vaccine is the first and only subunit influenza vaccine in China* indicated for administration at the full dose to the entire population aged 6 months and older, marking the official expansion of third-generation influenza vaccine technology to include infants and young children.
*As of the date of publication of this article*
Based on advanced purification processes and more sophisticated manufacturing technologies, this vaccine exhibits distinctive characteristics across multiple dimensions:
Excellent immunogenicity provides superior protection. The influenza virus subunit vaccine, leveraging its high-standard manufacturing process to extract high-purity antigens, effectively stimulates protective antibodies upon administration into the human body, thereby inducing a stronger immune response. The "Technical Guidelines for Influenza Vaccination in China (2025–2026)" state that multiple clinical studies have confirmed that administration of this vaccine to individuals aged 6 months and older demonstrates favorable immunogenicity. Specifically, for infants and young children aged 6–35 months, receiving the full dose (0.5 mL, subunit vaccine) of the vaccine elicits better immunogenicity than receiving the half dose (0.25 mL) of the split-virus vaccine [9].
More pure and safer. From the perspective of vaccine manufacturing processes, subunit vaccines undergo further deep purification compared to lytic vaccines—removing internal viral proteins and retaining only the high-purity HA and NA antigen components, thereby offering enhanced safety [8,9]. Due to the stringent manufacturing requirements, five doses of lytic vaccine raw materials are required to produce a single dose of subunit vaccine. Additionally, this vaccine is free from antibiotics and preservatives during production, thereby reducing the risk of allergic reactions at the source. In terms of the extraction process, Triton N-101 is used as the extraction agent for subunit vaccines; it has been classified as a non-hazardous substance under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), making it non-toxic and safer. The use of a milder extraction agent in conjunction with a more refined purification process ensures that the subunit vaccine maintains effective antigen purity while further minimizing exposure to unnecessary components, providing a more reliable safety guarantee.
Enhanced vaccination experience with improved convenience. Intramuscular injection is the most commonly used method of vaccination and one of the injection routes associated with the most pronounced pain; consequently, many children and adults are deterred from receiving vaccines due to the associated pain. The influenza virus subunit vaccine employs isotonic formulation technology, with rigorous control throughout the manufacturing process to ensure that the vaccine's osmotic pressure more closely matches that of human body fluids. This approach helps prevent local discomfort, irritation, or a burning sensation that may arise with hypertonic injection solutions, thereby reducing vaccination-related discomfort [10]. Additionally, this vaccine is administered using a robust, sharp 5-blade minimally invasive pre-filled syringe, which reduces the puncture resistance by at least 20%. This design not only facilitates the puncture procedure for healthcare providers but also conserves effort during large-scale, high-intensity influenza vaccination campaigns, significantly alleviates the pain experienced by recipients during the puncture, effectively improves the overall vaccination experience, and reduces the incidence of local adverse reactions [11].
brief summary
The technological evolution of influenza vaccines has consistently centered on achieving "greater efficacy and enhanced safety." From whole-virus inactivated vaccines to split-virus vaccines, and further to subunit vaccines, each iteration represents a more precise immune response and reduced exposure to unnecessary components. As a third-generation influenza vaccine, the subunit vaccine is derived from split-virus vaccines through extensive purification, retaining only the HA and NA antigens; this approach ensures robust immunogenicity while minimizing impurities and adverse reactions. For recipients, these advancements in manufacturing process purity and component precision ultimately translate into fewer adverse events and more tangible protection—this is precisely the significance of continuous technological advancement.
(If you require vaccination, please visit your local community health center for consultation and to schedule an appointment.)
References:
National Health Commission of the People's Republic of China. Guidelines for the Diagnosis and Treatment of Influenza (2025 Edition) [EB/OL].
Arranz-Herrero J, Presa J, Rius-Rocabert S, Arranz-Herrero J, Presa J, Rius-Rocabert S, et al. Determinants of poor clinical outcome in patients with influenza pneumonia: A systematic review and meta-analysis[J]. International Journal of Infectious Diseases, 2023, 131: 173-179.
National Center for Immunization and Respiratory Diseases (NCIRD). Clinical Signs and Symptoms of Influenza[EB/OL].
Gong Hui, Shen Xin, Yan Han, et al. Estimation of the disease burden of seasonal influenza in China, 2006–2019 [J]. National Medical Journal of China, 2021,101(8):560–567.
SHICHINOHE S, WATANABE T. Advances in adjuvanted influenza vaccines[J]. Vaccines, 2023, 11(8): 1391.
SHI H, ROSS T M. Inactivated recombinant influenza vaccine: the promising direction for the next generation of influenza vaccine[J]. Expert Review of Vaccines, 2024, 23(1): 409-418.
Chen Lisheng, Ma Xianghu, Cai Mingyong, et al. Development of a lytic influenza virus vaccine [J]. Chinese Journal of Biological Products, 2006,19(5):529–530.
National Immunization Program Technical Working Group – Influenza Vaccine Working Group. Technical Guidelines for Influenza Vaccination in China (2023–2024) [J]. Chinese Journal of Epidemiology, 2023,44(10):1507–1530.
National Immunization Program Technical Working Group – Influenza Vaccine Working Group. Technical Guidelines for Influenza Vaccination in China (2025–2026) [J]. Chinese Journal of Epidemiology, 2025,46(12):2097–2107.
Wang W.Wang W. Tolerability of hypertonic injectables[J]. International Journal of Pharmaceutics, 2015, 490(1-2): 308-318. DOI: 10.1016/j.ijpharm.2015.05.069.
Lü Min, Bai Shuang, Gao Pei, et al. A comparative study on pre-filled syringes with different needle designs for vaccination [J]. Chinese General Practice, 2019,17(11):1929–1932.
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How to choose a reliable influenza vaccine during the flu season? An evidence-based guide for subunit vaccines for all age groupsInfluenza (commonly referred to as the flu) is an acute respiratory infectious disease caused by the influenza virus. Unlike the common cold, influenza is highly contagious and is characterized primarily by systemic symptoms. Elderly individuals, children under the age of 5, patients with chronic diseases, pregnant women, and individuals with compromised immune systems are all considered high-risk populations for severe influenza [1]. A study based on national influenza surveillance and cause-of-death surveillance data revealed that, on average, there are 88,000 excess deaths related to influenza-associated respiratory diseases annually across China [2]. The total economic burden on outpatient patients with influenza ranges from RMB 801 to RMB 1,320, while the total economic burden on hospitalized influenza patients ranges from RMB 9,832 to RMB 23,833 [1]. In the face of the significant challenge posed by influenza, influenza vaccination is currently recognized worldwide as the most cost-effective and effective means of preventing influenza [1]. - The leap in influenza vaccine technology: from split-virus vaccines to whole-population subunit vaccines – what are the key advancements in the third-generation vaccines? 08-19
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