Influenza and influenza-like illnesses are seeing an unusually early surge in the D.C. region and across the U.S., charting an unpredictable course for the rest of the winter as RSV cases overwhelm pediatric hospitals, and a potential increase in COVID cases looms.

In a normal year, the flu hits its seasonal peak between December and January, but by late last month in D.C., Maryland, and Virginia incidents of the flu and similar illnesses were reaching levels not usually recorded until later in the winter. In the last week of October, DC Health recorded more than 300 positive tests, which is likely an undercount. During the same week in 2021, the city recorded just two.

“The positive tests that we do get each week… it’s only a tiny fraction of those people who are infected,” says Thomas Farley, Senior Deputy Director for the Department’s Community Health Administration. “But the trends over time can be reflective of what’s happening in the community.”

Not everyone who has the flu gets tested, which means health departments and the Centers for Disease Control and Prevention also collect data on those coming into outpatient settings with symptoms of influenza-like illnesses (ILI), which could include a fever, cough, or a sore throat. From Oct. 24 to Oct. 28, roughly 11% of outpatients in D.C. reported ILI — significantly higher than just 4% at this same time in 2021. In neighboring Virginia and Maryland, rates are similarly soaring, nearly double what they were at this time last year.

According to the CDC’s national influenza tracker, D.C. has some of the highest incidents in the country right now, along with Tennessee, Alabama, and South Carolina. Maryland and Virginia are also in the top tier of flu activity.

There’s likely several factors driving the early surge, according to Dr. Tara Palmore, an infectious disease physician and the hospital epidemiologist for George Washington University Hospital. Flu and ILI levels remained low for the past two seasons, thanks in part to travel restrictions, mask mandates, school closures, and other COVID prevention measures. The current surge in the D.C. area and other states in the southern U.S. mirrors what happened in the southern hemisphere in June, July, and August — months that constitute their winter and therefore when peak flu season typically falls. Countries like Chile experienced a premature rise in the flu, tipping off epidemiologists and virologists in that the U.S. could be in store for something similar.

“What happens in the southern hemisphere doesn’t always predict what happens in the northern hemisphere with regard to influenza,” Palmore says. “That said, that is what’s happening in the northern hemisphere — we are experiencing an atypically early flu season just as they did.”

However, in a more positive prediction, the flu shot used in Chile — which is formulated similarly to the one available in the U.S. — proved to be 49% effective against preventing hospitalization. While that may seem low, Palmore says that for an influenza vaccine it’s actually quite hopeful.

“When you think about how widespread influenza becomes during flu season, that’s a lot of hospitalizations that are averted,” she says.

Because the flu’s constantly evolving nature makes it so unpredictable, nailing down a vaccine that protects against mutating strains can be difficult. Every year, in January and February, a group of experts gathers to try and predict what strains will be circulating by October.

“They’re guessing at what’s going to be around almost a year later, 10 months later, and it’s a hard job,” says Dr. Donald Milton, a professor of environmental health at the University of Maryland who is currently preparing to launch a study on the airborne transmission of influenza. “Just as we’re now getting a bivalent booster against B.A.5 for the coronavirus, the flu can be hard to keep up with in a similar way.”

In Maryland, the only jurisdiction in the region that publishes public flu vaccination data, 19% of the population has received a flu shot this year, with residents aged 60-69 years making up a majority of the recipients. Residents aged 20-29 are the least vaccinated. In Montgomery County, nearly 25% of the population has received a vaccination, but that rate plummets to 14% in neighboring Prince George’s County.

Neither D.C. nor Virginia publish public data on vaccination uptake, but Farley with DC Health told DCist/WAMU that each week around 17,000 people are getting vaccinated, which is only around 2.5% of residents. Like Maryland, D.C. residents over the age of 65 make up most of the vaccinated population, with around 25% to 30% receiving a flu shot this year, according to Farley. A spokesperson for Virginia’s health department could not provide hard vaccination numbers, but tells DCist/WAMU that vaccinations overall are up from 2019. People over age 65 have high uptake in the commonwealth, while vaccinations for children six months to four years old have fallen.

“Treatment at hospitals and other healthcare facilities is increasing this flu season, which began earlier than what we typically see,” VDH spokesperson Cindy Clayton told DCist/WAMU in an email. “It’s particularly important for those at greater risk, including those age 65 and older, those under age 5 and pregnant women, to be protected by a flu vaccine.”

As flu cases spike, the region is already experiencing high levels of RSV, a respiratory virus that’s causing pediatric hospitals in the D.C. region to fill. Paired with a fall and winter where experts predict an uptick in COVID, officials are concerned that the three viruses converging could overwhelm local hospitals. For now, COVID cases in D.C. are still low. In Northern Virginia, case counts have plateaued after declining from an increase earlier this summer. Montgomery County’s case rates remain similarly low, and cases in Prince George’s County have begun to tick up in November.

Dr. Farley of DC Health says that hospitals in the District are already busy, and emphasized that vaccinations are the primary way to avoid overwhelming the healthcare system. Even for those in a younger age range with no underlying conditions, a case of the flu can still take someone out for several days to a week. (In D.C., you can receive a flu shot and a bivalent COVID booster at the same time at the city’s COVID Centers, located in each ward.)

“I think the hospitals can manage through this, but I think what everyone else ought to be focusing on is getting vaccinated so [you] don’t need a hospital stay,” he says.

Palmore says that as the fall and winter progress, the U.S.’s flu trajectory could mimic the trend in Chile and Australia, where cases dropped quickly after a large spike. It remains to be seen whether we experience yet another surge later in the winter, when a typical peak would occur.

“I don’t think we know yet where this is going to land,” Palmore says. “But the trajectory right now is not good.”