Is the new norovirus strain causing a surge in infections in the US? Symptoms to know

Norovirus cases have skyrocketed in the past few weeks, joining in the usual triumvirate of viruses – flu, RSV and Covid that raise infections every year. This unexpected rise in the stomach bug infections has left health authorities concerned. Experts attribute this rise to a new strain called GII.17[P17], that was behind nearly 70% of all norovirus outbreaks from September 2024 to December 2024, as per Centers for Disease Control and Prevention (CDC).
CDC mentions that 91 norovirus outbreaks have been reported from state health departments for the week ending Dec.

5, which is the highest number recorded in recent years.

Is the new strain more infectious?

While the increase in number of norovirus cases this year is being linked with the new strain of the virus, it’s not clear if the rise is specific to GII.17.

“It is too early to tell if this strain is associated with more severe norovirus disease,” Vinjé said, “but likely lower population immunity is the reason for the early surge of an otherwise seasonal increase of this virus,” said Jan Vinjé, PhD, Head of the CDC’s National Calcivirus Laboratory, had recently told CBS News.

All about GII.117 strain

The GII.17 strain is at least a decade back and emerged in 2014-15. Since then it has spread worldwide. However, the strain has come into light and started raising cases of norovirus only over a year ago between September 1, 2023 to August 31, 2024. While GII.17 has since then accounted for 109 norovirus outbreaks, GII.4, the earlier dominant strain since 2012 only caused 84 outbreaks, as per Vinje.
The recent rise in cases could be due to lesser immunity against GII.17. Apart from these two, there are various other strains of norovirus and getting infected with one doesn’t ensure protections against other types.

Symptoms of GII.117 strain

While there are multiple strains of norovirus, the symptoms more or less remain the same, as per experts. These are diarrhea, vomiting, nausea, and stomach pain, along with fever, headache, and body aches.
To prevent norovirus infection, washing hands with soap and hot water can help. Hand sanitizers aren’t that effective.
Norovirus symptoms

can be quite intense and even though it lasts 1-3 days, it can leave one severely dehydrated. While recovering from the infection, take small sips of water and light foods like soup.