How to distinguish seasonal flu and Covid-19?

The article was professionally consulted with Senior Doctor, Dr. Vu Van Tam - Infectious Internal Medicine - Department of Medical Examination & Internal Medicine - Vinmec Ha Long International General Hospital.

Seasonal flu and Corona flu are both respiratory illnesses, but caused by different viruses. COVID-19 is more contagious than the flu, but as more and more people are fully immunized, the spread will slow. So how can we distinguish common flu from Corona flu?

Both COVID-19 and seasonal flu can present varying degrees of symptoms, ranging from asymptomatic to severe symptoms. Common symptoms that COVID-19 and the flu both share include:
Fever or feeling hot/chills Cough Shortness of breath Fatigue Sore throat Runny or stuffy nose Muscle or body aches Headache Vomiting and diarrhea Change or loss of taste/smell (more common in COVID-19).

Because some of the symptoms of influenza, COVID-19, and respiratory illnesses in general are similar, it is not possible to distinguish between the common cold and Covid on the basis of symptoms alone. Only biological tests are valuable in diagnosing the causative agent. It is even possible for a person to be infected with both the flu and COVID-19 at the same time, thus having symptoms of both.
Of the 3 most common and obvious symptoms of Covid-19 are fever, dry cough and shortness of breath, only shortness of breath is unrelated to cold or flu. But according to research, people who get the full dose of the COVID-19 vaccine if infected will have no symptoms or mild symptoms and increasingly like the flu. Therefore, if you want to distinguish between flu and Covid-19, you also need to consider epidemiological factors.
In addition, loss of smell is the earliest and most commonly reported sign associated with SARS-CoV-2, and is a more effective marker for detecting people with COVID-19 than symptoms such as fever and cough. Unlike in colds and some flu cases where the cause of the loss of smell tends to be related to stuffy nose (stuffy nose due to mucus buildup), in COVID-19 sudden loss of smell can directly related to SARS-CoV-2 infection in the nasal epithelium and olfactory neurons without any obstruction. Therefore, people with sudden loss of smell should be suspected of being positive for COVID-19 and need testing for confirmation immediately.
Multiple simultaneous tests for seasonal influenza virus types A and B and SARS CoV-2 (the virus that causes COVID-19) have been researched and developed to distinguish if you are positive for influenza virus or Covid-19 or both two, some of which have been approved for human use. Initial flu/covid-19 combined testing, especially for those at high risk of complications, for early detection and prompt treatment whether you have the flu or SARS-CoV-2, will be an effective method in the future.

The flu is a relatively common, benign but potentially fatal illness, especially among young children, the elderly, and adults with chronic health conditions. Most healthy people with the flu will clear up on their own in a few days to 2 weeks, but some people will develop severe complications that require hospitalization. Compared with COVID-19, flu is more likely to cause a secondary bacterial infection. Diarrhea is also more common in children with the flu than in adults with the flu.
However, both common cold and Corona virus can lead to severe illness and complications, those most at risk include:
Elderly people With underlying medical conditions Infants and children Pregnant women Complications of COVID-19 and the flu include:
Pneumonia Respiratory failure Acute respiratory distress syndrome Sepsis Heart damage (eg, heart attack and stroke) Multiple organ failure (respiratory failure, kidney failure, shock) A worsening chronic condition (lung, heart, nervous system or diabetes related) Inflammation of the heart, brain, or muscle tissues Secondary infection. Compared to the flu, COVID-19 can cause more serious illness in some people and even lead to hospitalization and death in healthy people. Some people who contract COVID-19 after being discharged from the hospital may still have some post-COVID health problems or multisystem inflammatory syndrome.

In theory, a person could have the flu, as well as other respiratory illnesses, and COVID-19 at the same time. However, the presence of coronavirus could also play a role in preventing flu cases, because usually only one respiratory virus predominates in a population at a given time. That is, one virus tends to block the other. Medical professionals are still working on this issue.
In fact, when the Covid-19 pandemic hit, schools closed, travel was delayed and millions of people started working from home, the number of seasonal flu cases also quickly dropped to the lowest level in the world. history. As measures to prevent the spread of SARS-CoV-2 were taken, the number of flu cases dropped rapidly and has not yet increased again. The drop in seasonal flu infections during the Covid-19 outbreak has eased the burden on the health care system. But it should also be made clear that, although statistics show that flu rates have decreased (due to less exposure and reduced flu testing) during the Covid pandemic, it does not mean that the flu disappears that the flu virus continues to exist. changed and will return in the near future.
Unlike with SARS-CoV-2, people have natural immunity to influenza after years of exposure to different strains of influenza virus. However, just like SARS-CoV-2, influenza virus still constantly mutates and changes, new strains of influenza virus appear always capable of causing epidemics and even pandemics of influenza. In addition, if people's immunity to influenza declines during a pandemic due to less exposure, we may be more susceptible to influenza when exposed to influenza viruses. Although the exact time is not known, epidemiologists at the CDC say people may be more vulnerable to the virus when seasonal flu returns.
During the coming new normal - as millions return to public transit, restaurants, schools and offices - flu outbreaks may be more widespread than usual, or may occur at times unusual during the year. The flu and Covid-19 are both diseases that can cause dangerous complications, especially when you are in a high-risk group, so prevention and diagnosis of both should be concerned.

To get the flu shot, you should choose reputable hospitals/vaccination centers, provide quality vaccines, follow the injection process and follow up closely after vaccination, to ensure vaccination safety.
Currently, at Vinmec International General Hospital, we provide influenza vaccination service with outstanding advantages such as:
Commitment to high quality vaccine source, with clear origin, ensuring safety from the outset. check in, preserve until use; Vaccines are preserved by a cold chain meeting GSP standards with a modern cold storage system, allowing vaccines to be kept in the best conditions; Experienced medical team, able to advise and handle complex vaccination situations; Strict process: Before vaccination, customers are screened before vaccination with specialist doctors to help ensure the best health when vaccinated. The doctor will advise the family on the best preventive vaccines, suitable for each age group according to the latest recommendations of the Ministry of Health & World Health Organization as well as how to monitor the reaction after vaccination. ; With the advantage of multi-specialty, Vinmec can effectively monitor and handle post-vaccination problems (if any); Modern facilities: Post-vaccination monitoring room is fully equipped with emergency facilities; The team of doctors - nurses are trained in anaphylaxis emergency treatment to ensure timely and correct treatment when an incident occurs.