Author | HUANG Yida
Editor | ZHANG Fan
Olin Bio is a leading enterprise in China’s vaccine sector. Backed by its extremely scarce innovative superbug vaccine pipeline and steadily growing tetanus vaccine, its A-share stock price has embarked on a strong rally since 2024, with a maximum intrarange increase exceeding 500%. Amid the red-hot market sentiment, the company submitted an updated prospectus to the Hong Kong Stock Exchange on June 30, restarting its Hong Kong listing plan, hoping to secure a higher valuation by leveraging the strong prospects and scarcity of its innovative vaccine pipeline.
Furthermore, to ensure a smooth listing on the Hong Kong Stock Exchange, complete compliance rectification for historical tax matters, and clear compliance obstacles in the Hong Kong IPO process, the company has recently paid the previously announced taxes and late payment surcharges in full, totaling approximately 87.41 million yuan, which is roughly 4 times the company’s 2025 attributable net profit.
On July 11, the Phase III clinical data for Olin Bio’s core pipeline S. aureus vaccine was unblinded: the protection rate far exceeded the predefined design standards, and the safety profile was favorable, bringing it just one step away from commercialization. However, before the market could fully absorb this positive development, rumors alleging falsification of the vaccine’s clinical data spread rampantly. Although the company has issued a clarification announcement and filed a police report, its stock price was dragged into a sharp decline. From July 13 to July 20, in just 6 trading days, the stock price fell by over 40%, with a nearly 20% single-day drop on July 13.
Figure: A-share price trend of Olin Bio; Source: Wind, 36Kr
During the critical window for the company’s Hong Kong IPO, a single rumor triggered a collapse in its A-share price, sparking widespread market discussion. So what is the core reason behind this sharp short-term drop in Olin Bio’s stock price? What impact will this drastic short-term adjustment have on the company’s Hong Kong IPO?
01 Soaring A-Share Price, Highlighted Value of Core Pipeline
The company’s R&D pipeline is heavily focused on the superbug vaccine track, with its core pipeline consisting of four Class 1.1 innovative vaccines: recombinant Staphylococcus aureus vaccine, oral recombinant Helicobacter pylori vaccine, recombinant Pseudomonas aeruginosa vaccine, and recombinant Acinetobacter baumannii protein vaccine.
In terms of clinical progress, the Phase III clinical data of the S. aureus vaccine was unblinded on July 11, with a protection rate exceeding the design target and a favorable safety profile, bringing it on the verge of commercialization; the Helicobacter pylori vaccine is currently advancing to Phase I clinical trials; the other two key projects are still in the preclinical research stage. The company’s focus on superbug vaccines aligns with industry trends, as superbugs represented by multidrug-resistant and antibiotic-resistant bacteria have become a global public health challenge.
According to WHO data, in 2019, antibiotic-resistant bacterial infections caused 1.27 million direct deaths globally, with an additional 4.95 million indirect deaths. This has imposed a massive economic burden: according to World Bank projections, antibiotic resistance could lead to an extra $1 trillion in global spending by 2050, with annual global GDP losses reaching up to $3.4 trillion. This clearly demonstrates the strong global demand for superbug prevention and treatment.
Specifically, post-surgical incisions, indwelling catheters, burn wounds, and other sites are vulnerable to bacterial invasion, leading to common hospital-acquired infections such as wound suppuration, sepsis, and osteomyelitis. Superbugs, especially multidrug-resistant bacteria, exhibit strong drug resistance, forcing patients not only to extend their hospital stays but also to use high-priced specialized antibacterial drugs, significantly increasing the costs of diagnosis, treatment, monitoring, and nursing. Meanwhile, patients are forced to rest and unable to return to work, resulting in multiple direct and indirect economic losses.
Staphylococcus aureus, the target pathogen of the company’s core pipeline S. aureus vaccine, is a typical antibiotic-resistant bacterium that has developed resistance to many common antibiotics. It ranks high on the WHO’s priority list of bacterial pathogens, classified as a high-priority threat. Since there are no approved S. aureus vaccines worldwide, there is a large unmet demand for related prevention and treatment. According to the company’s prospectus data, the global number of S. aureus infection cases will reach 7.4 million by 2035, corresponding to an S. aureus vaccine market size of approximately $1.8 billion.
The core clinical application scenario of the S. aureus vaccine is to prevent post-surgical acquired bacterial infections, and S. aureus infections are highly prevalent, spanning multiple medical departments. Public data shows that S. aureus infections are frequently detected in ICUs, respiratory departments, pediatrics, obstetrics and gynecology, outpatient clinics, and stomatology departments. In 2025, the domestic detection rate of S. aureus infections reached 29%, corresponding to a huge patient population. Although the company’s S. aureus vaccine clinical trials primarily targeted post-orthopedic surgery patients, it is expected to expand to other high-risk and susceptible populations for S. aureus infections in the future.
Figure: Market size of S. aureus vaccines in China and globally; Source: Company prospectus, 36Kr
In terms of competitive landscape, Olin’s S. aureus vaccine has a commanding lead in clinical progress, with its Phase III trial results already unblinded and commercialization imminent. Meanwhile, S. aureus vaccine projects from pharmaceutical giants such as Pfizer, Merck, and GSK have all failed to achieve success, and apart from Olin, other global S. aureus vaccine-related research remains in the preclinical exploration stage.
Therefore, as the company’s S. aureus vaccine enters the commercialization phase in the future, it will enjoy exclusive market access for a considerable period of time, and its significant first-mover advantage will also bring substantial performance growth to the company. In fact, even before the unblinding, the market had high expectations for the vaccine’s eventual success, mainly based on the company’s multiple technical and R&D advantages in optimizing the vaccine’s immunization schedule, enhancing immune response levels with adjuvants, and grouping antigens in clinical trials. Combined with the commercial logic of exclusive market access after launch, the company’s A-share price has increased by over 500% from 2024 to the present.
In terms of valuation, the continuous previous rally drove the company’s valuation higher, with its peak PE-TTM exceeding 570x. After nearly 6 consecutive trading days of decline (as of July 20), with the stock price down 40%, the company’s valuation still remains as high as 180x.
Relying solely on the scale and performance flexibility of its existing business is clearly insufficient to justify such a high valuation. At the same time, the company’s other core pipelines besides S. aureus are all in preclinical stages, and the market typically does not assign valuations to these early-stage pipelines. Therefore, the core logic of the company’s valuation is primarily centered on the future prospects of its core pipeline, the S. aureus vaccine.
Following the recent realization of the positive news of the S. aureus vaccine unblinding, the company’s A-share price has plummeted consecutively, with the core reasons mainly falling into the following two categories:
1. The primary reason is the negative impact of rumors alleging falsification of the S. aureus vaccine’s clinical data. Although Olin Bio issued a clarification announcement and filed a police report, investors still chose to vote with their feet.
2. Some investors who exited recently accumulated substantial floating profits during the previous rally, so they chose to lock in their gains amid the news-driven volatility.
In the secondary market, it is very common for investors to sell off stocks in response to sudden negative news: stock market participants are inherently highly sensitive to all types of negative information. Even if the rumors are unfounded, most capital will prioritize risk aversion and exit before the truth comes to light, which can be considered a conventional “retreat first” operation.
The unique characteristics and strict regulation of the vaccine industry further amplify the market’s risk aversion tendency. In particular, biosafety incidents have extremely strong cross-sector transmission effects, and risks at a single enterprise can trigger valuation corrections across the entire sector. Taking the Changsheng Bio incident as an example, the year after the incident broke out, the total volume of domestic vaccine batch releases under strict supervision shrank sharply. While vaccine companies faced performance pressure, the vaccine sector also fell into long-term, large-scale volatile adjustments.
On the other hand, the vaccine track, with its vast imaginative space, has also spawned many short-term “star stocks”. For example, Chongqing Beer saw its stock price surge in its early years due to its hepatitis B vaccine concept, but subsequent R&D failures led to a continuous short-term decline in its stock price, even recording 9 consecutive limit-downs. From December 8 to 20, 2011, the stock price fell by 60% in 9 trading days.
Thus, by synthesizing historical incident cases and corresponding market performance, it is clear that whether it is a biosafety incident or an R&D failure, the resulting impact is a deeply ingrained pain for investors in the vaccine sector. Once signs of risk emerge, investors quickly flee to avoid risks, which explains why Olin Bio has recently experienced a sharp valuation drawdown.
From a short-to-medium-term perspective, after the unblinding of the S. aureus vaccine and before its approval for marketing, the relevant review and approval procedures still need to be completed. During the review and approval cycle, the company’s A-shares will still face high valuation pressure. Without the release of new major positive news, the company’s A-share price may enter a high-volatility phase.
The impact of the current market conditions on the Hong Kong IPO is mainly reflected in the valuation and corresponding financing scale. For listed companies with A+H dual listings, the A-share valuation is one of the important anchors for Hong Kong stock pricing. Olin’s current A-share price slump, significant valuation decline, and subsequent valuation pressure will all lead the market to revise its valuation expectations for its Hong Kong IPO, resulting in a simultaneous contraction in the fundraising scale.
02 Absolute Leader in the Tetanus Vaccine Segment
Olin’s existing business includes three currently marketed vaccine products: the tetanus vaccine, the AC conjugate vaccine (hereinafter referred to as AC), and the Hib vaccine (hereinafter referred to as Hib). All three are non-immunization-planned Class II vaccines. Among them, the tetanus vaccine is the company’s pillar product, not only contributing the vast majority of the company’s revenue and profit, but also serving as the core driving force for current performance growth.
Reflected in its financial statements, the company achieved revenue of 704 million yuan in 2025, a year-on-year increase of approximately 20%. By business segment, the tetanus vaccine generated revenue of 614 million yuan in the same period, accounting for as high as 87% of the company’s total revenue, with a year-on-year growth of approximately 15. Over a longer time horizon, the revenue share of the tetanus vaccine has long remained above 80%, and the revenue growth rate of this business has determined the overall revenue growth rate of the company in the past.
Figure: Olin Bio’s revenue and revenue structure; Source: Wind, 36Kr
Since AC was approved for marketing in 2021, it has gradually become an important marginal force driving the company’s performance growth. Financial statements show that AC generated revenue of 65 million yuan in 2025, a year-on-year increase of 147%, with its corresponding revenue share rising from 4.5% in 2024 to 9.3% in 2025. The revenue share of Hib has long been low, with revenue of only 19 million yuan in 2025, accounting for less than 3% of total revenue, and it has experienced continuous negative revenue growth in the past 3 years, making its contribution to the company’s performance almost negligible.
One core factor behind Olin’s steady growth in tetanus vaccine sales in recent years is the relatively favorable competitive landscape. This favorable competitive landscape consists of two layers:
1. Among different types of tetanus immunization preparations, the tetanus vaccine has certain advantages in the three dimensions of efficacy, safety, and cost-effectiveness.
2. In the tetanus vaccine track, the company’s product ranks first in market share, far ahead of competing products.
Tetanus is a typical post-traumatic bacterial infectious disease. Severe patients are prone to life-threatening complications such as asphyxia, pulmonary infection, and multiple organ failure, and the disease has an extremely high potential fatality rate, with a mortality rate of nearly 100% in severe cases.
In the current market, there are four main types of tetanus immunization preparations: tetanus antitoxin, equine tetanus immunoglobulin, human tetanus immunoglobulin, and tetanus vaccine. The first three products are mainly used for emergency treatment, but their protection periods are relatively short, only around 10 days. In terms of market demand, public data shows that there are approximately 1 million cases of tetanus globally each year, with 300,000 to 500,000 resulting in deaths.
Compared with tetanus antitoxin and equine tetanus immunoglobulin, the tetanus vaccine has a slightly slower onset of action but significant safety advantages: it is less likely to cause allergic reactions and typically provides protection for 5-10 years. Compared with human tetanus immunoglobulin, the main advantages of the tetanus vaccine are better accessibility, higher cost-effectiveness, and a longer protection period. Therefore, in non-emergency scenarios, and with the support of favorable relevant policies, tetanus vaccination has become the mainstream prevention method.
Olin Bio is the absolute leader in the tetanus vaccine track. As of now, there are 7 tetanus vaccines in the domestic market. The company’s product was approved for marketing in 2016, making it the earliest approved product among private enterprises, thus granting it a strong first-mover advantage. According to the company’s prospectus data, in terms of both batch release volume and revenue, the company’s product achieved market shares of 86.5% and 98.8% respectively in 2025, dominating the tetanus vaccine industry.
Figure: Competitive landscape of the tetanus vaccine market; Source: Company prospectus, 36Kr
Leveraging its absolute leading position in the tetanus vaccine track, the overall growth rate of the company’s period expenses matches its revenue growth rate. Over the past 3 years, the sales expense ratio has remained in the 52-54% range, the management expense ratio in the 11-16% range, and the R&D expense ratio in the 19-23% range. As biological products, vaccines have an extremely high gross profit margin, which has long remained stable above 90%. With the overall period expense expenditure level relatively stable, the company’s net profit margin has stayed in the 2-3% range over the past 3 years. From a performance-driven perspective, with a relatively stable cost structure, the core momentum driving the company’s performance growth is revenue growth.
In the medium to long term, the penetration rate of tetanus vaccines is far from