Symptoms of COVID-19 may vary for each person. However, they could appear in a certain order, such as fever, cough, sore throat, muscle pain, nausea, and diarrhea.

  • COVID-19 cases are rising again as the Omicron subvariant EG.5 (Eris) became the dominant strain in the United States and BA.2.86 (Pirola) became the dominant variant worldwide.
  • The upcoming 2023 flu season is expected to coincide with another COVID wave, and understanding how COVID-19 symptoms present can help minimize spread and ensure proper treatment.
  • Prior research has determined that COVID-19 symptoms often start in a certain order.
  • While influenza typically begins with a cough, the first symptom of COVID-19 is generally fever.
  • Still, some doctors who’ve seen patients with COVID-19 said that in their experience, the symptoms can be more varied.

A late-summer uptick in COVID-19 cases had many people wondering whether it’s time to mask up again or receive a booster shot to protect themselves against SARS-CoV-2 (the virus that causes COVID-19).

In August, the Centers for Disease Control and Prevention (CDC) reported that EG.5, nicknamed “Eris,” has surpassed XBB1.16 (“Arcturus“). The Eris COVID-19 variant has become the dominant subvariant in the United States, accounting for around 21% of circulating strains as COVID-related hospitalizations increased by nearly 19%.

An Omicron subvariant, EG.5 first emerged in November 2021 and was recently designated as a “variant of interest” by the World Health Organization (WHO), though not yet a “variant of concern.” As of August 7, 2023, the Eris variant has been reported in 51 countries, according to the WHO.

Meanwhile, the CDC reports that BA.2.86 (Pirola), a newly designated variant of SARS-CoV-2, was detected in multiple countries.

As of August 23, Pirola was reported in Denmark, South Africa, Israel, the United States, and the United Kingdom. It’s considered a notable variant because it has many genetic differences from previous mutations and may cause breakthrough infections.

“The new EG.5 variant does not seem to be more virulent (deadly), but it is likely more transmissible than the XBB1.16 variant,” Dr. Monica Gandhi, MPH, professor of medicine at the University of California, San Francisco, told Healthline. “XBB1.16 was the dominant strain for a long time, so EG.5 is most certainly more transmissible.”

The 2023 flu season is expected to dovetail with another COVID wave as the highly transmissible EG.5 and BA.2.86 Omicron subvariants circulate. Symptoms of COVID-19 often resemble the flu and may include fever and cough, but there are some key differences. Knowing the differences in symptoms could help minimize the spread of these infectious diseases.

According to Gandhi, symptoms of the new Eris variant, which she described as an “offshoot of the XBB series,” are no different than symptoms associated with other SARS-CoV-2 strains.

“There is no evidence that the symptoms caused by EG.5 differ from the symptoms caused by other Omicron subvariants,” Gandhi said. “The symptoms [of Eris] seem to be the same as with other recent subvariants of Omicron.”

Like other subvariants, Eris symptoms may include upper respiratory tract symptoms such as:

  • fever
  • coughing
  • sneezing
  • runny nose

Gandhi added that immunocompromised individuals, older, and those who are not immune to the virus could develop more severe lower respiratory tract symptoms like pneumonia.

If you display any of the above symptoms and test positive for COVID-19, you have likely contracted one of the new Omicron subvariants and should self-isolate for 5 days, which Gandhi said is the recommended period of isolation.

A 2020 study from the University of Southern California (USC) shed light on how COVID-19 symptoms present, which may help individuals recognize whether their cough is just a cough or something worse. The researchers determined that COVID-19 symptoms often start in a certain order:

  1. fever
  2. cough
  3. sore throat, muscle pain, or headache
  4. nausea or vomiting
  5. diarrhea

If you’re experiencing symptoms in this order, it is a good idea to get tested for COVID-19 so you can self-isolate and recover. The CDC offers resources for finding free COVID tests in your area.

“The study found that patients with seasonal flu more commonly developed a cough before the onset of fever,” Dr. Robert Glatter, assistant professor at the Zucker School of Medicine at Hofstra/Northwell, Emergency Medicine, told Healthline in an earlier interview.

“In reality, this may be difficult to discern since the flu often begins abruptly with a triad of symptoms, including back pain, chills, along with a dry cough.”

According to the study, while influenza typically begins with a cough or muscle pain, the first symptom of COVID-19 is fever.

“This order is especially important to know when we have overlapping cycles of illnesses like the flu that coincide with infections of COVID-19,” study author Peter Kuhn, PhD, professor of medicine, biomedical engineering, aerospace and mechanical engineering, and urology at USC, told Healthline in an earlier interview.

“Doctors can determine what steps to take to care for the patient, and they may prevent the patient’s condition from worsening.”

To predict the order of symptoms, researchers analyzed rates of symptom incidence collected by the World Health Organization (WHO) for more than 55,000 confirmed COVID-19 cases in China. To compare the order of COVID-19 symptoms to influenza, the researchers analyzed data from more than 2,000 influenza cases in North America, Europe, and the Southern Hemisphere reported to health authorities between 1994 and 1998.

“The order of the symptoms matters,” said Joseph Larsen, lead study author and USC Dornsife doctoral candidate. “Knowing that each illness progresses differently means that doctors can identify sooner whether someone likely has COVID-19, or another illness, which can help them make better treatment decisions.”

“It’s critically important to understand the progression of symptoms of people with the COVID-19 infection so you stop the spread of the disease — in effect, isolate and then initiate effective contact tracing,” Glatter said.

“This is quite relevant for a virus that is 2 to 3 times more transmissible than influenza, leading to outbreaks in clusters.”

He added that understanding the first symptoms not only helps patients seek testing more rapidly, but also to begin physically distancing themselves after the first symptoms begin.

“It also underscores the importance of wearing masks and hand hygiene upon learning of symptoms,” Glatter said.

He also finds that sudden loss of smell, taste, and inflammatory skin reactions “may be important clinical clues that may distinguish COVID-19 from seasonal influenza.”

In Glatter’s experience treating patients with COVID-19 in New York City, symptoms associated with the virus may be more varied than the USC study suggests.

“In general, while fever is usually the most commonly described initial symptom of COVID-19 infection, the reality of what I see on the front lines is more variable,” Glatter said. “In fact, some patients may present only with loss of taste or smell and otherwise feel well.”

Glatter added that he’s seen COVID-19 symptoms ranging from “COVID-toes” (chilblains) to reddish-blue discoloration of skin in response to acute inflammation, all in the absence of fever, cough, or other respiratory symptoms.

He said that other patients have also “presented with malaise, headache, and dizziness,” which in some ways resemble stroke symptoms but without fever, cough, or any evidence of upper respiratory symptoms.

“I have also seen patients present only with chest pain, devoid of any respiratory symptoms,” Glatter said. “The onset of nausea, vomiting, and diarrhea after onset of respiratory symptoms such as fever and cough may also suggest that a person may have COVID-19.”

According to Glatter, healthcare professionals need to be vigilant and keep an open mind when evaluating patients who may have symptoms associated with COVID-19 — particularly as new subvariants emerge.

“They don’t always present ‘according to the book,’ so you must cast a wide net when thinking about who may or may not have COVID-19,” he said.

If you’re wondering whether it’s time to mask up again, Gandhi said she is not particularly concerned about the new variant.

She explained that the EG.5 subvariant carries one additional mutation compared to the XBB1.5 subvariant, meaning the two subvariants are very similar.

She said the new COVID-19 boosters planned for mid-September were developed to protect against XBB1.5 and would, therefore, also protect against the EG.5 (Eris) variant.

“A recent preprint shows that the XBB1.5 booster will cover the EG.5 subvariant very well. So, the public could wait to get their booster shot until mid-September if they want the updated one and feel secure it will cover EG.5,” Gandhi noted.

The WHO recommends COVID-19 booster shots for sensitive groups, particularly immunocompromised individuals, people with multiple comorbidities, and those who are older than 65.

“I am not very concerned about the new variant because COVID-19 is not an eradicable virus (it is found in too many animal reservoirs for one thing, with rapid evolution in animals such as deer) so we will always see new subvariants,” Gandhi said.

“However, we have high rates of population immunity in the United States at this time (up to 96.4% antibody positivity as of fall of 2022). Memory B cells — generated by the vaccines or as a result of a prior infection — have been shown to recognize the virus, including its variants. Specifically, if memory B cells see a variant, they are able to make antibodies adapted to the variant or subvariant,” she added.

Gandhi explained that both COVID-19 vaccines and natural infection trigger the production of T cells.

“B cells serve as memory banks to produce antibodies when needed [and] T cells both help B cells make antibodies and help recruit cells to attack the pathogen directly. T cell immunity from the vaccines remains protective across variants ‘from alpha to omicron.’ Our T cell response, even across a mutated spike protein, is so robust that we have not seen Omicron yet able to evade the many T cells that descend upon the mutated virus to fight severe disease,” Gandhi noted.

The new COVID-19 variant Eris is the dominant SARS-CoV-2 strain in the U.S., but the symptoms present similarly to prior Omicron subvariants.

Understanding the difference between COVID-19 symptoms and flu symptoms could be helpful in minimizing spread and getting appropriate treatment.

A 2020 study compared symptoms from people who had the flu versus COVID-19 and found that COVID-19 symptoms occur in a particular order.

Experts with frontline experience emphasize that this progression isn’t always how the disease manifests, but it’s still a useful guide for healthcare professionals.