As the winter season continues, Pima County is seeing an increase in cases of the flu and the recently on-the-rise norovirus, while COVID-19 and respiratory viruses are comparatively down.
So far this season, which started in September 2024, the Pima County Health Department has recorded a total of 2,228 flu cases, 212 RSV cases, and 5,166 COVID-19 cases.
In norovirus numbers, Pima County has seen an increase, with the health department recording a total of 447 tested and confirmed cases from lab reports in 2024 compared to 356 cases in 2023.
According to Pima County Health Department numbers, influenza and COVID-19 cases have increased above their five-season average while respiratory syncytial virus (RSV) is below its five-season average.
The influenza or flu virus, which has a type A and type B, is a contagious respiratory virus spread by droplets when an infected person talks, coughs, or sneezes, according to the PCHD website.
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COVID, which had led to the deaths of nearly 1.2 million people in the U.S. as of June 1, 2024, is caused by the SARS-CoV-2 virus, according to the Centers for Disease Control and Prevention (CDC). The disease most commonly has caused respiratory symptoms like cold, the flu or pneumonia, CDC reported.
“We are still below the four-year average for COVID right now,” said Lindsay Kohler, chief epidemiologist and head of epidemiology at the county health department, referring to the four years since the COVID-19 pandemic started. “It was up a little bit from last week, but compared to the four-season average for the last four years, we’re down 83%, but that’s just because of the pandemic. So, fairly stable with COVID right now, and looks like it’s stable the last week but it’s been coming down the last few weeks.”
RSV, which affects infants and older adults more, is a common respiratory virus that causes mild cold-like symptoms, according to the CDC.
Norovirus is on the rise, here are a few things you can do about it according to experts. Veuer’s Keri Lumm has more.
Norovirus, popularly referred to as a “stomach flu” or “stomach bug,” is a contagious virus which primarily causes vomiting and diarrhea and whose biggest threat is severe dehydration, according to the CDC. The CDC terms it the leading cause of vomiting, diarrhea and foodborne illness in the United States, stating that it leads to acute gastroenteritis, an inflammation of the stomach or intestines.
“For norovirus, we have had some outbreaks in the last couple of months, and we’ve had over 400 cases of norovirus in Pima County,” said Kohler.
However, health department officials confirmed that Pima County had not seen any human cases of the bird flu virus. They also reported the latest county wastewater samples from Dec. 19 were negative for the bird flu’s H5N1 virus.
The bird flu virus, called an Avian influenza Type A virus, is generally found in poultry and wild birds, but has made its way to create rare cases of human infections that manifest in different ways from eye infections, upper respiratory issues, to pneumonia.
The Maricopa County Department of Public Health’s routine wastewater surveillance recently reported a detection of an influenza subtype associated with avian flu or H5N1 in local wastewater, according to its website. The three cities where the virus was detected were Phoenix, Surprise and Tempe, although the website said it wasn’t “currently possible to confirm a precise source location of the viral detection.”
Trends in the diseases
Respiratory illnesses tend to peak in late fall and winter, since people are indoors more and could spread respiratory viruses and infections through the air, said Dr. Theresa Cullen, Pima County’s public health director.
“COVID tends to have two peaks, a summer peak and a winter peak, in Arizona,” said Cullen. “If you think about it, the summer, when it’s peaking is when people are inside because it’s so hot here, right? Whereas other environments in other parts of the United States, they might not see that.”
Cullen has reservations about making predictions based on data, considering the amount of unofficial home testing taking place today, while health officials primarily track and follow hospitalizations.
“The season for norovirus is more like starting around Thanksgiving, typically till like around Easter,” said Kohler. “… It’s a season where a lot of people are getting together for holidays and things like that. And so, it’s hard to clean; it’s in the environment. If someone is sick and they don’t wash their hands, it could be in their food.”
Kohler said the general trend to avoid getting infected by norovirus has been to push the usage of hand sanitizer, but she said it doesn’t really kill norovirus. The real prevention tactic is to wash your hands with soap and water, and scrub them to get norovirus off, she said.
Both Kohler and Cullen emphasized that washing hands with soap thoroughly and regularly is need to avoid not just norovirus but all the respiratory viruses talked about.
“We’re not seeing anything unexpected,” said Cullen, referring to the recent recorded numbers. “Ideally, what we would like to see is the numbers going down because people would get vaccinated. So, RSV, flu, COVID, all have a vaccination that can help prevent the disease or prevent serious disease.”
Kohler and Cullen also suggested staying home if you feel sick, and wearing the N-95 mask if you have to be around other people.
Age groups most affected
Cullen said RSV routinely affects those who are young, since their airways aren’t as developed.
On the other hand, elderly people are affected by all the diseases, with severity ranging to increased risk of hospitalization and mortality. The immune response fades as you get older, Cullen explained.
Additionally, if you have underlying respiratory disease like chronic obstructive pulmonary disease, cardiac disease, congestive heart failure or diabetes, there’s an increased risk. Elderly individuals could also be immunocompromised in general, due to having had transplants or immunosuppressive medications for certain diseases.
“COVID has a higher mortality rate than influenza, which has a higher mortality rate than RSV, depending population wise,” said Cullen. “COVID is 1.5 times more likely to, if you have a serious infection, cause death than influenza.”
However, there are also many other respiratory diseases out there, said Cullen. It’s just that these three are the ones we talk about the most, because we have vaccination and treatment for them, she said.
