The Flu Is Here: Here's How to Get Through It

[Originally published: Dec. 16, 2022. Updated: Jan. 8, 2024.]

These days, a fever, sore throat, and body aches typically mean one of two unwelcome viruses: flu or COVID-19. What's more, both are on the rise, according to the Centers for Disease Control and Prevention (CDC).

In fact, the theoretical “tripledemic,” which describes a combination of flu, COVID-19, and RSV (respiratory syncytial virus) cases occurring at the same time, is more of a “twindemic,” with COVID and flu cases spiking and RSV numbers steadily declining in children.

One good piece of news is that it’s not too late to get an annual flu shot or updated COVID-19 vaccine.

“It’s important to remember that flu is a disease that kills thousands of people every year,” says Thomas Murray, MD, PhD, a pediatric infectious diseases specialist. “While the flu vaccine might not keep everyone from getting flu, it will help prevent its spread and help keep people out of the hospital. If more people are protected from flu and therefore stay out of the hospital, it frees up resources to better care for anyone who comes in with any problem.”

We talked more with Dr. Murray and Matthew Ellman, MD, a Yale Medicine primary care physician and director of Yale Medicine Internal Medicine Associates, about all things flu.

While the most common flu symptoms remain the same year to year, COVID and its evolving subvariants, including JN.1 (a strain that appears to be highly transmissible), have created more of a puzzle when it comes to differentiating it from other illnesses.

For the most part, flu is notable for its rapid onset and symptoms such as a fever of 100 to 104 degrees, muscle pains, and a non-productive cough, he says. “But it’s important to note that older people and those with issues with their immune system might not get a fever,” Dr. Ellman says.

Dr. Murray agrees that it can be “very difficult” to differentiate among possible reasons a person is ill, including flu, COVID, and other respiratory illnesses. “Sudden onset of symptoms, in general, is more likely to be flu, but it’s certainly not a guarantee,” he says.

Since home rapid COVID tests are readily available, it’s a good idea to test for it first when you have any symptoms associated with a virus, doctors say. However, a negative rapid COVID doesn’t mean you’re in the clear, Dr. Murray cautions.

That’s because you could have COVID and it’s not yet showing up on the test (rapid tests are not as “sensitive” as PCR tests), or you could have flu or another illness. “Therefore, it’s best to stay home when you have any symptoms that could be flu or COVID. And if you go out in public, wear a mask,” Dr. Murray says.

If a test is not easily available or if you know you were exposed to flu and/or COVID, it’s also fine for people who are otherwise in good health to stay home and skip the test.

However, if you are considered “high risk” for complications from either illness, you may want a test to confirm it; you may be eligible for antiviral treatments (more on those below).

Dr. Murray gives the following example of when a test is unnecessary: “If someone in your house has flu and two days later you have a fever, muscle aches, and chills, I don't think you need a test. You've got flu,” he says. “But if you don’t have a known exposure, or you went to a party, and it’s unclear if people there had COVID, flu, or anything else, then if you really want to know, you should test.”

For most healthy children and adults, home care is the best way to treat flu. This includes rest, drinking plenty of fluids, and, if needed, taking over-the-counter medications to lower fevers or reduce muscle pain.

But for those at risk of severe disease or complications from flu, an antiviral treatment is recommended. And the list of qualifications for risk of significant illness is quite long, notes Dr. Ellman. “This includes anyone over age 65, children under age 2, pregnant women or women who have delivered a baby within two weeks, people in nursing homes and long-term care facilities, and those with chronic asthma, heart conditions, diabetes, cancer, obesity, and more,” he says.

The first antiviral treatment recommended for children and adults is typically oseltamivir (brand name: Tamiflu). The medication, which comes in pill and liquid form, is taken twice a day for five days and should be started within 48 hours of symptom onset.

It’s important to know that antiviral medications take a little time to work. “They will shorten the course of illness by a couple of days, and the earlier you take it, the better,” Dr. Murray says.

There are also other antiviral treatments for children and adults, Dr. Murray notes. The Centers for Disease Control & Prevention (CDC) provides information on them here, as well as a complete list of conditions that make people more susceptible to developing serious complications from the flu.

Tamiflu side effects, which include nausea and vomiting, are rare in adults, Dr. Ellman says, but children are more likely to experience gastrointestinal symptoms. In rare cases, some children also experience neuropsychiatric symptoms, Dr. Murray says. These can include delirium, delusions, tremors, and anxiety symptoms, among others, so they must be monitored for changes in behavior while on the drug.

“If a child is hospitalized or if they have underlying problems that put them at high risk for being admitted to the hospital or having a serious illness, we would treat them with antivirals because the potential benefits outweigh the adverse effects,” says Dr. Murray. “But with children who are otherwise healthy, parents have to decide if the benefits are worth the side effects that come with antiviral treatment.”

The other value of antiviral flu treatments, Dr. Murray says, is that they can be used prophylactically with high-risk close contacts. “If you have a household member who has an immune problem, cancer, or a lung problem and they're at a very high risk for being hospitalized from flu, then you can give these medicines to prevent influenza once they've been exposed to a close contact,” he says.

Most people who get the flu will recover within a few days to about two weeks, but there are risks of complications, including pneumonia.

For children, Dr. Murray says parents should look out for breathing trouble and dehydration (low urine output, including few to no wet diapers in babies). “If you have any concerns, call your pediatrician,” he says. “And if a child who has flu starts to feel better and then suddenly gets worse, call your provider right away because sometimes they can have a bacterial infection after influenza.”

Many bacterial infections require antibiotic treatment. Unfortunately, there continues to be reported shortages of amoxicillin, a common medication. But medical experts stress that while this has been the case on and off, other antibiotics are available that can be used to treat ear infections, pneumonia, and other issues.

During flu season, multiple strains—flu A and B—circulate. After infection with one strain, you should have immunity from that strain for the rest of the flu season. However, you could get infected with a different strain, Dr. Murray points out.

The CDC recommends that people 65 and older who have not yet gotten their flu vaccine try to find a specially formulated one because they are more at risk for serious illness. There are three types: Fluzone high-dose quadrivalent vaccine, Fluad quadrivalent adjuvanted flu vaccine, and Flublok quadrivalent recombinant flu vaccine.

According to the CDC, the recommendation was based on a review of studies suggesting that, for this age group, these vaccines are potentially more effective than standard flu vaccines. Of the three recommended for older adults, Fluzone carries the most evidence of superior efficacy over the standard flu vaccine, according to the CDC. A 2014 study in The New England Journal of Medicine showed Fluzone to be 24% more effective at flu prevention in people 65 and older than the standard vaccine.