Omicron That Seems Like the Flu but Isn't Really the Flu? Is It True? (Lee Jin-kyung's Health Tips)

Symptoms and Characteristics of Omicron Different from Cold and Flu

[Asia Economy Reporter Jin-kyung Lee] In the past, when the weather was cold and you suddenly had a sore throat or a runny nose, it was common to just assume it was a cold. However, since the emergence of the COVID-19 virus, symptoms of colds, flu, and COVID-19 can overlap, so mild symptoms can no longer be overlooked. Especially with Omicron, unlike other variants, it spreads more easily and often presents symptoms similar to a cold rather than fever or loss of smell, so it can be mistaken for a cold in the early stages of infection, requiring caution. Although the number of confirmed Omicron infections is rapidly increasing day by day, many people assume that Omicron has a lower severity and fatality rate than the Delta variant because its symptoms resemble those of a cold. However, experts say it is still too early to be complacent. Nowadays, many infected individuals are asymptomatic or show only mild symptoms, making it difficult to determine infection status based on symptoms alone. So how can we distinguish between a cold and an Omicron infection ourselves? For prompt response after infection, let's carefully examine the differences in symptoms between Omicron, flu, and cold, and how to respond after infection.

● Symptoms and Characteristics of Omicron, Cold, and Flu

▶ Cold

Colds usually show symptoms 1 to 3 days after exposure to the virus, and the severity of symptoms can vary depending on the patient's age, underlying conditions, and immune status. Symptoms include sneezing, runny nose, nasal congestion, sore throat, sputum, and muscle pain, with little or no fever or only a slight fever. Most symptoms improve within 1 to 2 weeks, but severe cases may experience complications such as acute otitis media, sinusitis, or pneumonia.

▶ Flu

Flu symptoms suddenly appear with systemic signs such as headache, fever, chills, muscle pain, fatigue, and loss of appetite, accompanied by respiratory symptoms like sore throat, cough, runny nose, and nasal congestion. However, sometimes coughing or sore throat occurs without fever, leading to confusion with a common cold and neglect of symptoms. In elderly or chronically ill patients, worsening symptoms can lead to severe complications such as pneumonia.

▶ Omicron

The Omicron variant does not commonly cause the high fever or loss of smell and taste seen in early COVID-19 infections. Instead, symptoms such as sneezing, sore throat, runny nose, cough, fatigue, muscle pain, and lack of energy are more common. Fever is often mild or absent. Additionally, some infected individuals remain asymptomatic without any symptoms, and symptoms can vary from person to person. A characteristic of COVID-19 is the rapid progression of the disease, especially in patients with underlying conditions or the elderly, where symptoms can worsen quickly, so caution is necessary. Rapid recovery after infection is important.

● Can Omicron be distinguished from a cold?

It is practically difficult to distinguish sore throat caused by a cold from that caused by Omicron, but by examining the condition of confirmed Omicron patients, a rough distinction is possible. If severe sore throat lasts for two days but there is little or no fever or only a short mild fever, Omicron infection should be suspected. Common symptoms of Omicron infection include sneezing, runny nose, fatigue (lack of energy), skin rash, cold sweats, diarrhea, and vomiting. If you experience sore throat, fatigue, and muscle pain that you have not experienced before, it may not be a common cold, so it is advisable to quickly use a self-test kit for testing.

● Is Omicron different from the Delta variant in symptoms?

Omicron, which has stronger transmissibility than the Delta variant, mainly causes upper respiratory tract infections with more prominent sore throat symptoms, making it easy to mistake for a cold. Its symptoms are milder than those of the Delta variant, and even if fever occurs, it tends to be short-lived. This contrasts with the Delta variant, which can cause pneumonia by infecting the lungs. Therefore, even without fever, if symptoms such as cough, runny nose, or sore throat lasting more than three days appear, rapid antigen testing or self-test kits should be used for quick testing.

● Will a self-test kit show positive during the Omicron incubation period?

The incubation period for Omicron is about 2 to 4 days, roughly half that of the original COVID-19 and Delta variant, with a short incubation period of about 1 day and 9 hours until infectiousness begins. Its transmissibility during the incubation and generation periods is higher than that of the original COVID-19 and Delta variant. (Statistics may vary by country and period.) Testing with a self-test kit during the incubation period may yield either positive or negative results. Therefore, it is recommended to perform self-testing 2 to 3 days after suspected infection. If symptoms are mild and difficult to judge, repeated testing several times is advisable. However, since test kits can be hard to obtain, checking for nearby hospitals offering rapid antigen tests and getting tested there is another option. For high-risk groups, prompt testing is important, so visiting a screening clinic for PCR testing is recommended.

● Is Omicron really not dangerous like a cold?

Some argue that Omicron is no different from a common cold and advocate easing social distancing measures due to its low severity rate. However, the Korea Disease Control and Prevention Agency clearly states that Omicron is different from a common cold. Medical professionals say that although symptoms may be milder than previous COVID-19 variants, Omicron is more severe than the flu, with a fatality rate about twice that of seasonal flu, so vigilance should not be relaxed. Many confirmed Omicron patients have experienced suffering beyond that of a cold or flu, so experts urge not to take early cold symptoms lightly and to get tested promptly.

● Can Omicron infection be accurately detected with a single self-test kit?

Priority groups designated by the government can receive free PCR testing at nationwide screening clinics, but if you are not in a priority group, rapid antigen testing can be done using self-test kits available at public health centers, screening clinics, respiratory clinics, pharmacies, convenience stores, or online. Although self-test kits are convenient, they are less accurate than PCR tests. The sensitivity of rapid antigen tests (the probability of correctly identifying positives) is below 50% even when performed by medical personnel, and below 20% when self-administered. To maximize accuracy, it is important to follow the correct usage instructions and conduct multiple tests rather than relying on a single test. If a positive result is obtained, visit a screening clinic for PCR testing. Since PCR results take about a day, immediate home isolation is necessary. Used test kits should be placed in the disposal bag included with the product and brought to screening clinics for proper medical waste disposal. If the result is negative, disposal in regular waste bags is acceptable.

● With increasing Omicron cases, is easing quarantine measures possible?

Medical professionals acknowledge that younger people have a lower risk of severe illness, but symptoms are not mild. They are concerned that increasing case numbers could overwhelm treatment capacity. Even if some restrictions on the number of people and business hours are adjusted considering self-employed opposition, easing social distancing could accelerate spread. Therefore, they warn that it is premature to discuss easing measures while case numbers remain high. Since severe cases can occur even among young people, many experts caution against treating the Omicron variant as a simple cold or flu.

● How should one respond if infected with Omicron?

▶ Step 1: Symptom Identification

If you have symptoms such as sneezing, headache, pharyngitis, or fever, or if a household member is confirmed positive, you should test yourself as soon as possible using a self-antigen test kit. If obtaining a test kit is difficult, you can visit the nearest screening clinic for antigen testing. Since antigen tests are less accurate than PCR tests, a negative result does not guarantee safety. Omicron often tests negative within 2 days of symptom onset but positive on days 3 to 4. Therefore, even if the first test is negative, repeat antigen testing on days 3 to 4, and if positive, confirm infection with PCR testing, experts advise.

▶ Step 2: Repeated Testing

Omicron viral load is low immediately after symptom onset and peaks 24 to 36 hours later. Experts recommend not to be reassured by an initial negative self-test but to repeat testing 3 to 4 times if possible. High-risk individuals with underlying conditions should test daily until symptoms completely resolve.

▶ If you are high-risk or symptoms are severe, visit a hospital immediately for treatment

Currently, Omicron-infected individuals with mild or no symptoms are advised to self-diagnose and recover at home with medication. However, those with underlying conditions or in high-risk groups must visit a hospital for medical care. Infants and children cannot monitor their health independently, so even during home treatment, hydration and respiratory status should be carefully observed. If health issues arise, seek medical attention promptly.

▶ Wear KF94 masks and strictly follow daily quarantine measures

Experts emphasize that due to Omicron's high transmissibility, wearing KF94 masks that effectively block droplets, frequent handwashing, and disinfecting surfaces of used items are crucial for protecting healthy family members. If you wear a mask and maintain physical distancing, brief contact with a confirmed case does not require excessive worry, but you should carefully monitor yourself for any symptoms afterward.

▶ Know and consume nutrients that help boost immunity

Experts say that to prevent the flu, it is important to regularly consume nutrients that enhance immunity. Vitamins (A, B6, B12, C, E, folate) and trace minerals (zinc, copper, selenium, iron) boost immune function and are best obtained through food. Foods that enhance immunity include milk, cheese (vitamins A, B12), oily fish (vitamins A, B6, B12, selenium), nuts and seeds (vitamin E, copper, iron), meat (zinc, iron, selenium, vitamins B6, B12), garlic (vitamin B, allicin), green leafy vegetables (vitamins A, B6, folate, iron), and fruits (vitamins A, C).

▶ Eat foods that help fight viruses

When infected with flu or viruses, protein intake is important for maintaining body weight and muscle mass, and consuming foods that provide sufficient energy is essential for recovery. Therefore, consume protein-rich foods such as meat, eggs, fish, legumes, and nuts, and have healthy snacks to increase calorie intake. Drink warm water frequently to maintain hydration. The body requires more vitamin C and zinc when fighting respiratory diseases, so it is beneficial to eat fruits rich in vitamin C like tangerines and strawberries, vegetables like broccoli, bell peppers, and cabbage, and zinc-rich foods such as meat and cheese.

This content was produced with the assistance of AI translation services.