At the end of March 2025, 20 students and a teacher who went on a three-day exchange study tour to Zhaoqing experienced a norovirus outbreak. The students and the teacher began to develop symptoms consistent with the norovirus infection, including vomiting, diarrhoea, and fever. Among the group, eight tested positive for norovirus . As summer travel commences, it’s imperative to know the symptoms of norovirus, how it spreads, and the key prevention strategies one can take.

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What is Norovirus?

Norovirus, also often referred to as the stomach flu or stomach bug, is the leading cause of vomiting and diarrhoea worldwide. Affecting people of all ages, this highly contagious virus causes acute gastroenteritis, which is an inflammation of the stomach and intestines. Despite being called the “stomach flu,” norovirus is not related to the influenza virus, which causes respiratory illness. It is known for its rapid onset of symptoms and its ability to spread quickly in environments with crowded spaces, like schools, nursing homes, hotels and cruise ships. Norovirus outbreaks are common, particularly during winter months, and can affect individuals who ingest contaminated food or come into contact with infected individuals.

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What are the Symptoms of Norovirus?

Norovirus typically causes a sudden onset of nausea, vomiting, diarrhoea, and stomach pain. Some people may also develop a headache or a mild fever as part of their symptoms. While both children and adults experience similar signs, adults are more likely to suffer from diarrhoea, whereas children tend to vomit more frequently. Symptoms usually begin within 1 to 2 days after exposure, although in some cases, illness can start as early as 12 hours after infection. Once symptoms appear, individuals often feel abruptly unwell and may vomit several times throughout the day. Although most people recover within 1 to 2 days without lasting health effects, the virus can continue to shed in stool for up to two weeks, allowing recovered individuals to still pass it on to others.

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How Can One Get Norovirus?

Norovirus is highly contagious and can be transmitted in a range of everyday situations. It can spread through a person’s vomitus or faeces, where microscopic traces in infected vomit or stool can contaminate hands, food, and water.

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Eating Contaminated Food

Food can be contaminated at any stage, whether during production, preparation, or serving. Norovirus is often found in shellfish as they can be harvested from polluted waters. Raw produce also carries norovirus, as infected workers handling the produce could pass on the virus. Food safety practices are essential, especially when eating out or travelling in a foreign country.

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Direct Contact with Infected Individuals

Close personal contact with someone who is infected can also easily spread norovirus. Those who care for a sick person, share food or utensils, or even shake hands after contact with vomit, stool, or saliva particles are all susceptible to the norovirus.Since the virus can be present in high amounts in bodily fluids, even casual exposure can be enough to cause illness. It is essential to maintain strict hygiene standards, especially when caring for someone who is sick, to prevent the virus from spreading from person to person.

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Touching Contaminated Surfaces

Norovirus can survive on hard surfaces for several days, making it easy to contract norovirus without realizing it. Common contact points on objects like doorknobs, elevator buttons, light switches, and countertops are all high-risk areas for norovirus. When you touch a contaminated surface and place your fingers in your mouth, you risk introducing the virus into your body. This can happen whether you are eating, biting your nails, or simply rubbing your lips.

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How to Prevent Norovirus

Because norovirus is highly contagious and resistant to many standard cleaning methods, taking active steps to prevent infection is essential. Maintaining good hygiene, practicing proper food handling, and thoroughly disinfecting can significantly reduce your risk of contracting the virus or spreading it to others.

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Practice Proper Hand Hygiene

Handwashing is the most effective way to prevent norovirus infection. Always wash your hands thoroughly with soap and warm water for at least 20 seconds, ensuring you scrub between fingers, around your nails, and on your wrists. Key times for handwashing include after using the toilet, in conjunction with diaper changes, cleaning up vomit, preparing or eating food, and handling medication. Hand sanitizers may reduce some germs but are not reliable against norovirus, so they should only be used alongside proper handwashing, not as a substitute.

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Disinfect Surfaces Frequently

Norovirus can survive on hard surfaces for long periods, making regular disinfection essential. You should clean and disinfect commonly touched items such as doorknobs, light switches, elevator buttons, and kitchen counters using a bleach-based cleaner or another disinfectant proven effective against norovirus. Pay special attention to areas in the kitchen and bathroom, especially if someone in the household is ill. It is recommended to clean any areas contaminated by vomit or diarrhoea immediately to prevent the virus from spreading.

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Handling Food Safely

Foodborne outbreaks are a significant way norovirus spreads. Wash fruits and vegetables thoroughly under running water before eating or preparing them, even if they will be peeled. Cook shellfish, particularly oysters, to a proper internal temperature of above 63°C, as norovirus can survive undercooked seafood. Avoid preparing food for others if you are feeling unwell or have recently recovered, as you can still spread the virus for up to two weeks after symptoms subside.

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Staying Ahead of Norovirus

Norovirus is a common and potentially harmful virus, particularly when it spreads rapidly through communities, schools, or during group travel, as seen with the school tour to mainland China. It’s crucial to understand how the virus spreads and to recognise the early symptoms to prevent larger outbreaks. By taking everyday precautions, you can protect yourself and also help safeguard those around you. As travel and gatherings become more frequent, especially in the warmer months, staying vigilant against norovirus remains essential.

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Blue Care Consultation Services

Blue Care Medical Centres staffed with highly qualified family doctors provide family doctor consultation.

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For appointment, please contact Blue Care Medical Centre.

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Tel : 2523 1808

Address : 10/F, 33 Des Voeux Road Central, Central, Hong Kong
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