Norovirus Vaccine - A Step Closer to Safety

Introduction

The stomach flu virus, or Norovirus, is highly contagious and causes vomiting and diarrhea. Individuals must drink plenty of fluids if they suspect they may have Norovirus since it can lead to dehydration. The Norovirus can be countered through excellent cleanliness, which includes frequent hand washing and avoiding contact with sick people. Following its infection, it is crucial to drink plenty of fluids and rest until patients feel better. This column will go into further detail on the facts listed above about the nasty stomach bug.

What Is Norovirus?

Formerly known as Norwalk-like viruses, Norovirus refers to a group of highly contagious and infectious viruses that can precipitate a cascade of unfortunate changes within the human body. The disease is also known by several other names, such as the stomach bug, stomach flu, and winter vomiting disease. They are important pathogens believed to be responsible for many gastroenteritis outbreaks worldwide, with approximately 21 million cases reported annually in the United States. It is also the most common cause of foodborne illness in the United States, with as much as half of all food-related outbreaks in the USA believed to be caused by Norovirus.

How Does the Disease Spread?

As established before, Norovirus is one of the most infectious viruses, insinuating that it leads to large outbreaks in places like old homes, hospitals, cruise ships, and childcare centers. It also results in hundreds and thousands of lost work hours from sick people. The virus enters via fecal-oral routes or through the mouth to infect a person. Following ingestion, the virus incubates in the gastrointestinal tract for 12 to 48 hours. It also most likely multiplies in the small intestine, causing tissue damage and leading to myriad symptoms.

People acquire the virus through direct contact with sick people and by coming into contact with surfaces, food, or water contaminated with the virus. The virus is shed in large quantities, approximately millions to billions in stool and vomit. Furthermore, the virus particles can also be aerosolized over several feet when a person vomits. It may take only 20 virus particles to make someone sick. Though shedding is highest during a person's symptoms and immediately after they resolve, people have been known to shed the virus for weeks after feeling better, potentially exposing and infecting others as well.

What Are the Signs and Symptoms Associated With Norovirus?

The nasty stomach bug that causes the Norovirus disease, commonly known as winter vomiting, is associated with several signs and symptoms. They include -

• Gastroenteritis, inflammation of the stomach and the small intestine.

• Severe, uncontrolled diarrhea.

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• Vomiting.

• Nausea.

• Abdominal cramps.

• Severe fatigue

• Weakness.

• Headache.

• Sudden and occasional chills.

• Fever in certain individuals.

• Severe muscle aches.

• Decreased urination.

• Dryness of mouth and throat.

• Bouts of dizziness while trying to stand up.

What Are the Biggest Obstacles in Managing Norovirus Disease?

Managing the Norovirus disease can be a highly tricky, confusing, puzzling, daunting, and challenging task, considering the mind-baffling nature of the virus. The viruses of this group are highly contagious and difficult to control and contain since they are highly infectious. The virus is also known to evolve and mutate several times, creating new strains that result in pandemics. So far, outbreaks have occurred over half a dozen times in the last two decades. This, coupled with the fact that Norovirus infection does not create long-term immunity in most people, increases an individual's susceptibility to being affected multiple times throughout their life. Additionally, the viruses can persist on surfaces, in food, and in water and, on most occasions, cannot be entirely inactivated by most common disinfectants, sanitizers, food processing, and food preservation methods.

What Is the Commotion About the Norovirus Vaccine?

It can be disheartening to know that for several years, there was no vaccine to prevent the incidence of Norovirus disease. However, it is vital to understand that not everyone is susceptible to any one strain of Norovirus. A subset of the world's population has a genetic makeup that prevents particular viral strains from infecting. Therefore, it is suspected that not everyone infected with the virus shows symptoms. This further complicates the efforts required to prevent and control the spread of the virus. Additionally, because the virus is shed in large amounts in vomit and feces and is persistent and resistant, it is clear that a Norovirus outbreak can result from one ill individual or contamination event, thereby necessitating the need for a vaccine to minimize casualties and maximize prevention.

Owing to advancements in medicine and research today, several studies have been undertaken to create a novel vaccine that can help contain Norovirus disease. The studies, however, have been done on virus-like particles that mimic the Norovirus and on animals such as mice. A few of the vaccines under trial are as follows -

• The Takeda Norovirus vaccine.

• The Vaxart Norovirus vaccine.

• The NVSI Norovirus vaccine.

• The Longkoma Norovirus vaccine.

The studies have concluded that the vaccines can help reduce the symptoms, such as vomiting and diarrhea, by a significant proportion, if not eliminate the disease. A substantial reduction in such symptoms can help in faster recovery in a large part of the population, and prevent further casualties, especially in individuals with other debilitating conditions, which, combined with the Norovirus disease, can prove fatal.

What Are the Challenges in the Development of a Vaccine Against Norovirus Disease?

Several factors challenge scientists when creating a novel vaccine. The obstacles include the following factors -

• The Norovirus has a broad spectrum of antigenic and genetic diversity; an infection by a single strain does not confer long-term immunity.

• Infections with Noroviruses trigger cellular and humoral immunological reactions. Although antibody-mediated immunity is generally well understood, little is known about the cellular immune response to Norovirus infection, further complicating the process.

• The human Norovirus cannot be grown under artificial conditions, such as in cell cultures.

Conclusion

Although it may seem like food poisoning, the Norovirus disease differs from food poisoning and can be highly debilitating for the affected. It can result in many symptoms, rendering an individual weak and dehydrated. Such individuals experience bouts of vomiting and diarrhea and should be monitored closely, ensuring proper fluid intake to prevent dehydration and its unkind consequences. Like any viral disease, it runs its due course and takes time to be flushed out from the system. Considering its high rate of infectivity, The World Health Organization has prioritized creating a vaccine that can help prevent and contain this disease. Until then, palliative care and isolation of the affected individuals remain the only methods to combat this disease.

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