Sick Season Is in Full Swing. From Flu and RSV to Norovirus, Here’s What’s Going Around

The Surge in Winter Illnesses: A Perfect Storm of Viruses

As winter sets in, the United States is grappling with a dramatic surge in respiratory illnesses, including influenza, COVID-19, and respiratory syncytial virus (RSV). According to the latest data from the Centers for Disease Control and Prevention (CDC), the number of positive influenza cases has skyrocketed since December, with a strong upward trend observed across the country. This year’s flu season is shaping up to be particularly challenging, with a potentially deadly mix of viruses circulating simultaneously. Add to this the unexpected rise in norovirus outbreaks, and it’s no wonder that it feels like everyone around you is getting sick.

Respiratory Illnesses: A Triple Threat

The current surge in respiratory illnesses is being driven by three main culprits: influenza, COVID-19, and RSV. Each of these viruses poses unique challenges, and together, they are putting a strain on healthcare systems nationwide. Influenza has been increasing steadily over the past month, with cases surging upward in recent weeks. “It’s roaring along, that’s for sure,” says William Schaffner, MD, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center. “Influenza has been increasing over the last month and has really surged upwards.”

Meanwhile, COVID-19 continues to linger in the background, flaring up regularly alongside the flu. Unlike influenza and RSV, COVID-19 typically has two yearly peaks: a smaller one in the summer and a larger one during the winter season. This year, emergency department visits for COVID-19 are lower compared to flu and RSV, but they are increasing, according to the CDC.

RSV, a virus that primarily affects young children and older adults, is also causing significant concern. It is estimated that RSV leads to up to 80,000 hospitalizations annually among children under the age of 5. “The thing we really worry about is RSV in young children, less than six months of age,” says Dean Winslow, MD, a professor of Medicine and infectious disease expert at Stanford Medicine. “They can actually get very, very sick and develop a condition called bronchiolitis, an infection and inflammation of the small airways.”

Norovirus: The Highly Contagious Stomach Bug

Just as respiratory illnesses are surging, norovirus, the notorious stomach bug often associated with cruise ship outbreaks, has also been making headlines. Known less flatteringly as “winter vomiting disease,” norovirus has caused an unusually high number of outbreaks in recent weeks. During the first week of December alone, state health departments reported 91 norovirus outbreaks, far exceeding the average of previous years.

A novel strain of norovirus, known as GII.17[P17], has been linked to many of these outbreaks. Samples from 70% of patients involved in norovirus outbreaks tested positive for this new strain, compared to the previously more common GII.4 strain. Norovirus is notoriously contagious and can spread easily in enclosed spaces, such as cruise ships, nursing homes, schools, and prisons. “Other similar populations include senior citizen centers, schools, and prisons,” says Schaffner. “Any of these enclosed or semi-enclosed populations can be the locus for a big outbreak.”

Comparing This Year to Previous Seasons

Despite the alarming surge in viral activity, this year’s illness trends are not entirely unprecedented. Experts point out that, aside from the COVID-19 pandemic, this year’s flu and RSV activity is generally in line with previous seasons. “It’s really not too much worse than other years,” says Winslow. However, the presence of COVID-19 adds an extra layer of complexity to the situation. Since the pandemic began in 2020, COVID-19 has become a persistent part of our viral landscape, regularly flaring up alongside the flu and other respiratory viruses. “It’s now part of our viral ecology, like these other viruses,” Schaffner notes.

Protecting Yourself and Your Loved Ones

To navigate this winter’s Perfect Storm of viruses, it’s crucial to take a multi-pronged approach to protect yourself and your loved ones. Vaccination remains the most effective way to prevent infection or reduce the severity of symptoms for both COVID-19 and the flu. While there is no widely available vaccine for RSV, researchers are making progress in this area, and certain high-risk groups may be eligible for vaccination. In addition to vaccination, antiviral medications such as Paxlovid for COVID-19 and Tamiflu (oseltamivir) for the flu can be prescribed by your doctor if you develop symptoms.

Beyond vaccination, good old-fashioned prevention strategies are key. “Wash hands frequently,” advises Judith O’Donnell, MD, section chief of Infectious Diseases at Penn Presbyterian Medical Center. “Consider wearing a well-fitting mask if you must be out and have significant concerns about getting sick. Masking remains highly effective.” Avoiding large gatherings, staying home when sick, and sanitizing surfaces can also help inhibit the spread of respiratory viruses like influenza, COVID-19, and RSV. However, when it comes to norovirus, hand sanitizers may not be enough. “Most of the hand sanitizers are alcohol-based,” says Winslow. “Norovirus is a very hearty organism in terms of persisting in the environment, so the best thing from an individual perspective is very thorough handwashing.”

Looking Ahead: The Future of Winter Illnesses

As the winter months continue, it’s clear that this year’s surge in respiratory and gastrointestinal illnesses is far from over. While the current trends are challenging, experts emphasize that they are not entirely unexpected. By staying informed, taking preventive measures, and staying vigilant, we can reduce our risk of getting sick and help slow the spread of these viruses in our communities. As Schaffner notes, “It’s really not too much worse than other years,” but that doesn’t mean we can let our guard down. The key is to remain proactive and prepared, whether that means getting vaccinated, washing our hands, or simply staying home when we’re under the weather.