• COVID-19 cases are rising as the JN.1 “Pirola” variant accounts for 40% of cases worldwide.
  • Respiratory virus season is in full swing in the Northern Hemisphere with COVID-19, the flu, and RSV illnesses circulating widely.
  • Understanding how COVID-19 symptoms present can help minimize spread and help you get the right 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, though symptoms may vary.

A winter surge COVID-19 cases may have you wondering whether it’s time to mask up again or get vaccinated or boosted to protect yourself from getting sick.

In December 2023, the Centers for Disease Control and Prevention (CDC) reported that JN.1, nicknamed “Pirola,” made up 15–29% of all COVID-19 cases in the United States. By January 2024, JN.1 accounted for 40% of COVID-19 cases worldwide.

JN.1 is a close relative to the Omicron subvariant BA.2.86, which the CDC has been tracking since August 2023 when it was detected in multiple countries. It was first detected in the U.S. in September and accounted for less than 0.1% of COVID cases by the end of October.

Pirola is considered a notable SARS-CoV-2 subvariant because it has genetic differences from previous mutations and may cause breakthrough infections. The only difference between JN.1 and BA.2.86 (also known as Pirola), is a small change in the spike protein.

As the 2024 respiratory illness season peaks in the U.S., it may seem like just about everyone around you is getting sick, whether from the flu, respiratory syncytial virus (RSV), or COVID-19.

Symptoms of COVID-19 may resemble common respiratory viruses, but there are some key differences. Knowing the differences in symptoms could help minimize the spread of these infectious diseases.

According to Dr. Monica Gandhi, MPH, professor of medicine at the University of California, San Francisco, symptoms of new COVID variants are similar to symptoms associated with other SARS-CoV-2 strains.

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

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

  • fever
  • coughing
  • sneezing
  • runny nose

Gandhi added that immunocompromised individuals, older adults, and people 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 may have contracted the JN.1 Pirola variant and should self-isolate for 5 days, which Gandhi noted is the current 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, experts are not particularly concerned about the new variants, particularly for vaccinated individuals.

The updated COVID-19 boosters should continue to offer protection against severe illness from the new variants.

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.

JN.1, nicknamed “Pirola,” is the dominant SARS-CoV-2 strain in the U.S. and globally. Symptoms of the JN.1 Pirola variant may present similarly to prior Omicron subvariants.

Understanding the difference between COVID-19 symptoms and flu or RSV symptoms could be helpful in minimizing spread and getting the right 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.