Hepatitis A, caused by the hepatitis A virus (HAV), is the most common form of acute viral hepatitis worldwide among types A, B, C, and E (1). HAV infection is globally widespread. According to the World Health Organization (WHO), there are approximately 159 million new HAV infections each year, resulting in around 1.5 million clinical cases and 39,000 deaths (2–4).

Hepatitis A may present as isolated (sporadic) cases or occur in the form of epidemics (5). Its incidence varies greatly between countries and is closely linked to factors such as socio-demographic index, hygiene, and sanitary conditions (6). While high-income countries generally maintain good hygiene standards, these remain insufficient in many low-and middle-income regions (3, 7, 8).

In developed countries, most adults are susceptible to HAV infection. Here, outbreaks are typically driven by interpersonal transmission within high-risk groups, whereas foodborne infections are more likely to cause sporadic cases (9). However several outbreaks in these regions have been associated with contaminated food (10, 11). This shift is likely influenced by increasing international travel and global food imports, which may alter the epidemiology of hepatitis A by facilitating both outbreaks in developed countries and global transmission of the virus (12, 13).

HAV is primarily transmitted through the ingestion of food or water contaminated with feces from an infected individual, or via direct contact with an infected person (14).

Even minimal quantities—such as 1,300 infectious units per gram of food—are sufficient to cause infection. This high transmission potential is partly due to the virus’s remarkable environmental stability. HAV can remain infectious in water, soil, and on contaminated surfaces (fomites).

Its persistence is further enhanced at low temperatures, which allows it to survive for extended periods in various food matrices, including leafy greens, carrots, fennel, green onions, spinach, berries, aromatic herbs, and shellfish. For instance, HAV has been found to survive for months on frozen berries and remain infectious on surfaces depending on temperature and humidity conditions (15, 16). Furthermore, under low humidity, it can persist on foods like lettuce, bell peppers, melon, and dried tomatoes.

To inactivate HAV thermally, cooking or boiling at a minimum of 85°C (185°F) for at least one minute is required. These characteristics allow HAV to remain viable throughout the entire food chain—from production to consumption—posing a risk of fecal contamination at any stage in what is known as the “farm to fork” pathway (17).

These findings confirm that HAV can persist on food long enough to threaten consumer health. While some hygiene treatments may help reduce viral load, none have proven completely effective in eliminating the virus (18).

The virus’s resistance to acidic pH enables it to reach the intestinal tract in an infectious form; it’s incubation period range from 15 to 50 days (19).

During this time, the hepatitis A virus (HAV) is excreted in large quantities in feces, reaching concentrations up to 10¹¹ genome copies per gram just before symptom onset (20). After the appearance of jaundice, viral shedding decreases rapidly as anti-HAV antibodies develop. Nonetheless, infants and young children can continue shedding the virus for up to six months post-infection (21).

Food handlers play a crucial role in preventing HAV transmission. If infected, they can transmit the virus to susceptible individuals through the food they prepare (22) and have been identified as a major source of foodborne hepatitis A outbreaks (23). A single infected food handler can transmit the virus to dozens or even hundreds of individuals during food harvesting, handling, preparation, or distribution, significantly impacting public health and healthcare costs (24–26). The primary transmission route through food handlers is direct hand-to-food contact.

Throughout the food production chain, agricultural products undergo multiple stages of handling, increasing the risk of cross-contamination by infected workers or contaminated surfaces (20). Experimental studies have shown that HAV can maintain its infectivity on hands for at least four hours (27). Simply rinsing hands with water may reduce the viral load by 10 to 100 times but is insufficient for complete removal (18). Although HAV cannot replicate outside a host, such as in food and water, its low infectious dose poses a significant risk to consumers regardless of the contamination level (28).

Despite wide variation in the number of food handlers worldwide, their role in ensuring food safety is universally essential. Nevertheless, food safety strategies have generally prioritized environmental hygiene and sanitation over direct preventive measures such as vaccination. As of now, mandatory HAV vaccination for food handlers is enforced only in a few countries, such as Germany, while in most others it remains voluntary or merely recommended.

Establishing clear epidemiological links between foodborne HAV infections and specific contamination sources remains a major challenge. This difficulty stems from the global nature of food supply chains, where ingredients can originate from distant locations, be incorporated into numerous products, and become contaminated at very low levels. As a result, outbreaks are often detected too late to trace the source effectively. The foods most commonly implicated in outbreaks include shellfish, leafy greens, and both fresh and frozen fruits—particularly berries. However, due to the possibility of cross-contamination, virtually any food can be involved (20).

Therefore, understanding HAV endemicity and identifying the main sources of infection—both human and food-related—are crucial for developing targeted prevention strategies. In line with this, a recent ECDC report on hepatitis A prevention emphasizes the importance of collaboration between public health authorities and the food safety sector to help reduce the burden of foodborne infections (29).

Other narrative reviews from recent literature have examined foodborne HAV outbreaks and the central role of food handlers in transmission, highlighting the potential benefit of immunizing food workers. Such measures could enhance food safety in compliance with HACCP (Hazard Analysis and Critical Control Points) principles while also mitigating biological risk among food industry personnel (17).

The objective of this systematic review is to assess the impact of food handlers on foodborne hepatitis A (HAV) infections, examining the crucial role they play in transmitting the virus through food.

In line with PROSPERO registration standards, this review focuses on identifying and evaluating studies that explore the role of HAV vaccination in reducing the risk of transmission via food handlers. The main outcome of the review is to establish that HAV vaccination plays a significant role in preventing foodborne HAV infections transmitted through food handlers, in light of the current epidemiology of the virus.

The study protocol was registered in PROSPERO (registration number: CRD420250651930). This review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, ensuring compliance with current standards for systematic review reporting. The research question was formulated using the PICO framework. The study population included individuals exposed to HAV infection, with a particular focus on food handlers. The primary outcomes assessed were the prevalence of HAV infection and its association with food handling practices.

The prevention of HAV infection through vaccination of food handlers remains an important question for public health protection. Epidemiological studies in literature are increasing in number and quality, with access to more data and information and the ability to utilize genetic sequencing techniques. Alternative but valid systems, such as computerized databases to analyze food consumption and processing, allow us to obtain valuable, important, and potentially real-time information on epidemic trends.

However, significant caveats remain in outbreak management: numerical underestimation (both in the number of outbreaks and in the number of cases within a single episode), the risk of recall bias for past events, and the time factor, which is fundamental in the epidemiological approach.

Observational studies dominate the literature and exhibit a moderate risk of bias. These studies often fail to systematically report vaccination data. Based on the GRADE methodology, these limitations translate into a very low certainty of evidence about recommendation for vaccination of food handlers against HAV. This rating reflects the overall quality of evidence, which is considered very low, and the presence of significant methodological and practical limitations that hinder a robust assessment of the intervention’s effectiveness (see Table 3).

Also noteworthy is adherence to control and prevention measures, which remains difficult to evaluate and often subject to biases related to staff self-assessment, and finally, food service personnel’s willingness to undergo vaccination.

The CDC suggests a cautious approach to vaccination, strongly recommending it for personnel at risk for other reasons (staff returning from travel to endemic areas or MSM). Finally, it should be emphasized that the current social climate leads many people to find temporary or even seasonal jobs in food service, thereby exponentially expanding the pool of individuals who should undergo HAV vaccination and making monitoring virtually impossible. It is therefore crucial to implement the education about food safety among both permanent and temporary food handlers.

The public health “one-size-fits-all” approach is therefore potentially burdened with problems, as is the approach tied to profiling MSM individuals or those who have traveled from endemic countries.

From the perspective of individual food business owners, the direct economic benefits of vaccinating their employees, although not immediately apparent—especially in regions with a low incidence of HAV—could be considered both to prevent business disruptions resulting from infectious episodes and to comply with major food safety regulations.

Specifically, the European Regulation EC852/2004 (Annex 2) requires that “…No person suffering from or being a carrier of a disease likely to be transmitted through food or afflicted, for example, with diarrhea is to be permitted to handle food or enter any food-handling area in any capacity if there is any likelihood of direct or indirect contamination. Any person so affected and employed in a food business and who is likely to come into contact with food is to report immediately the illness or symptoms, and if possible, their causes, to the food business operator (56).

In conclusion, although the literature suggests that HAV vaccination can be an effective tool for preventing outbreaks, employer and employee participation in vaccination within the food industry could be encouraged through public incentives or subsidies.

Further, the improvement of surveillance and reporting of HAV cases would be invaluable in order to provide better data for assessing the risk associated with food handlers and for informing targeted prevention strategies.