Norovirus is a highly contagious virus that causes inflammation in the stomach and intestines, a condition known as gastroenteritis. It is frequently referred to as the “stomach flu” or “winter vomiting bug,” although it is not related to the influenza virus. Norovirus is a very common cause of acute gastroenteritis, affecting millions of people annually. This illness often leads to sudden symptoms like nausea, vomiting, diarrhea, and stomach pain, typically lasting one to three days. Many people who have experienced norovirus wonder if they can become infected again.
Understanding Norovirus Immunity
Reinfection with norovirus is indeed possible, and individuals can contract the illness multiple times throughout their lives. The immunity acquired after a norovirus infection is often short-lived, offering protection for only a few months to a year. This differs from other viral infections where immunity might provide long-term or lifelong protection.
Immunity to norovirus is also specific to the particular strain that caused the initial illness. An infection with one type of norovirus may not protect an individual against other types or even new variants of the same type. This characteristic contributes to recurring infections.
Factors Contributing to Reinfection
The primary reason reinfection is common lies in the extensive diversity of norovirus strains. There are numerous different strains, or genotypes, of norovirus, and being infected with one strain does not provide immunity against others. This means an individual could recover from one strain and then encounter a different strain shortly after, leading to another illness episode.
The protection developed against a specific norovirus strain is often temporary. Even against the same strain, immunity typically lasts for a limited period, a few months to a year. This transient nature of immunity, combined with the continuous emergence of new norovirus strains, makes individuals susceptible to repeated infections over time.
Preventing Norovirus Illness
Preventing norovirus illness primarily involves diligent hygiene practices due to its highly contagious nature. Rigorous handwashing with soap and water for at least 20 seconds is paramount, especially after using the toilet or changing diapers, and before eating, preparing, or handling food. Alcohol-based hand sanitizers are generally less effective against norovirus compared to soap and water because the virus has a tough exterior that alcohol struggles to penetrate.
Proper cleaning and disinfection of contaminated surfaces are also crucial and important in preventing spread. A chlorine bleach solution with a concentration of 1,000 to 5,000 ppm (5 to 25 tablespoons of household bleach per gallon of water) is recommended for disinfecting surfaces. Surfaces should remain wet with the solution for at least one to five minutes. Avoiding direct contact with sick individuals and staying home for at least 48 hours after symptoms stop helps to limit transmission, especially for those who prepare food or care for others. Additionally, careful food handling, such as thoroughly washing fruits and vegetables and cooking shellfish to an internal temperature of at least 145°F, also reduces the risk of foodborne transmission.