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Since the widespread introduction of vaccination programs in 2006, the burden of disease from rotavirus in both the U.S. and abroad has decreased substantially.

In fact, vaccination proved so successful in the U.S. that rotavirus is now rarely definitively diagnosed and few children are ever hospitalized for rotavirus-related dehydration. This is in stark contrast to the pre-vaccine era.

Rotavirus: Then

"At our hospital, we would see 400 children a year hospitalized with dehydration [from rotavirus]," Paul Offit, MD, a physician in the Division of Infectious Diseases at Children's Hospital of Philadelphia, told 麻豆传媒.

Now, however, "many pediatric residents in our hospital have never seen a case of rotavirus," Offit said. "But the virus still circulates in the community."

It is virtually impossible to discuss the current state of rotavirus in the U.S. without understanding the full impact the virus had on children and healthcare systems before vaccines became available. , in the pre-vaccine era among U.S. children less than age 5, rotavirus annually led to:

• More than 400,000 doctor visits
• Over 200,000 emergency room visits
• 55,000 to 70,000 hospitalizations
• 20 to 60 deaths

"Routinely, during the winter months we would have the hospitals filled with kids with rotavirus," who needed treatment for dehydration, Robert Frenck, Jr., MD, a pediatrician and director of the Center for Vaccine Research at Cincinnati Children's Hospital, commented to 麻豆传媒.

Genon Wicina, MD, a pediatrician at Cleveland Clinic Martin Health in Stuart, Florida, also confirmed that, before the vaccines, rotavirus would nearly overwhelm healthcare systems in the winter and springtime. "Our schedule would be full of children with diarrhea and fever," she said.

Wicina, who works in an outpatient setting, added, "I would probably be admitting a child every day, every other day, to the hospitals. The hospitals would be full and they wouldn't have room for all the kids to be admitted because they were all in there with dehydration from rotavirus."

Unfortunately, worldwide, rotavirus infections continue to be the leading cause of severe diarrhea in children age 5 and younger. Although the numbers have improved since the introduction of the vaccine, the virus currently results in at least and at among children under the age of 5 across the globe. The majority of these deaths occur in .

However, before the introduction of rotavirus vaccine programs, an estimated 500,000 young children died worldwide every year from rotavirus-associated dehydration. "It was the biggest killer of infants and young children in the world," Offit emphasized.

Rotavirus: Now

According to CDC data, the vaccines proved to be remarkably effective in the years after they were introduced. and rotavirus-associated healthcare utilization dropped dramatically, and the vaccines now prevent about of moderate-to-severe infections.

"In areas where the rotavirus vaccine was highly implemented, rates of rotavirus-related doctor visits and hospitalizations plummeted," Frenck said.

"What people say now is that the norovirus is the leading cause of diarrheal illness for kids coming into the ED [emergency department] or the hospital -- and that's true. But it's not because norovirus has increased," Frenck explained. "It's because rotavirus basically fell off the table."

The seasonality and geographic spread of rotavirus infections in the U.S. have also evolved. Before widespread adoption of the vaccines, cases of rotavirus disease in the U.S. were highest in the winter and spring months, peaking in the Southwest during December and moving to the Northeast by April and May. However, according to the CDC, this pattern has become . Rotavirus seasons have gotten shorter since the introduction of the vaccines, and until the pandemic, rotavirus gastroenteritis had biennial peaks in even years.

Has the lifting of COVID-19 restrictions resulted in any surges of rotavirus-associated illness, like those seen with respiratory syncytial virus or influenza? "I can't say that in my practice that I have seen a specific trend with the GI [gastrointestinal] illnesses," Wicina commented.

However, the CDC has identified some fluctuations in rotavirus seasonality. "During the COVID-19 pandemic in 2020-2021, we saw much lower levels of rotavirus activity," a spokesperson from the CDC told 麻豆传媒 in an email. "Since 2022, rotavirus seasons with increased activity during the winter months have reestablished."

Of note, the biennial trend from the prepandemic period has not yet returned. "Instead, what we've observed nationally is that the 2022 and 2023 rotavirus seasons were similar to the high rotavirus seasons in the prepandemic period," the CDC spokesperson said.

Outbreaks in the Post-Vaccine Era

The CDC's National Respiratory and Enteric Virus Surveillance System (NREVSS) tracks the percentage of based on reporting by participating laboratories, as well as . Rotavirus is not a nationally notifiable disease, "but periodically outbreaks are reported, especially among groups at higher risk and groups in congregate living situations," the CDC spokesperson commented.

In a , the CDC documented three rotavirus outbreaks in California from late March 2017 through May 2017. One of the outbreaks occurred at a child care center providing care to 215 children and another occurred at an assisted living and memory care facility housing 44 residents and employing 40 staff. These two outbreaks were relatively mild, with no reported hospitalizations or deaths.

However, the third outbreak occurred at a subacute inpatient care facility for patients less than age 21 with complex medical needs -- an already vulnerable population with low vaccination coverage. Although most of these cases resolved without complications, one 22-month-old child with preexisting respiratory failure died from rotavirus-induced dehydration. This child, in addition to 16 others in the facility, had not been vaccinated for rotavirus, most likely because live vaccines are discouraged in critically ill children, the report said.

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