Flu, COVID-19, Common Cold: What to Expect This Fall

September 17, 2021

This article was medically reviewed by Dr. Theodore Markou.

As fall approaches, so do concerns surrounding “flu season”– especially with the highly contagious COVID-19 Delta variant still impacting our communities. According to the CDC, flu cases were an all-time low last year, even in the midst of the COVID-19 pandemic, but this year is expected to be quite different. Since the flu was not prevalent last year, immunity to flu viruses likely waned.  And now with loosened restrictions, inconsistent masking, and a partially vaccinated country, an uptick in flu cases along with the common cold is inevitable. That’s why it’s important to be aware of the differences between seasonal viruses that cause the flu and common cold versus COVID-19. ID Care infectious disease specialist Dr. Theodore Markou shares everything you need to know about the flu, how its symptoms compare to COVID-19 and the common cold, and how to prevent, diagnose, and treat these contagious respiratory illnesses.

What and When is Flu Season?

Flu season is the time period when the influenza virus is most contagious, when the weather is colder and humidity drops, allowing the flu virus to survive and circulate. Human behavior also contributes to this as the cold weather forces people to congregate indoors in close proximity, allowing us to spread flu virus particles easier from person to person. Crowded schools, offices, and sporting events can be risky environments. And flu season can last 7-8 consecutive months, typically beginning in late September, peaking in December through March, and ending in late Spring around early May.

What Causes the Flu Compared to a Cold and COVID-19?

There are different families of viruses that cause each of these contagious respiratory illnesses. Influenza is caused by the flu family of viruses that mostly affect the nose, throat, and lungs.

There are four different types of flu viruses (A, B, C, D), but seasonal flu cases in humans are tied to the most common influenza virus type A followed by influenza virus type B. It is interesting to note that influenza A is most known to cause the pandemics we see every 1-2 decades, like the 2009 swine flu caused by the H1N1 influenza virus, as it can infect animals and then jump to humans. In contrast, influenza B solely infects humans.

Dr. Markou reports that type A is the most contagious and accounts for about 75% of flu cases annually. Influenza A will likely peak in the winter between December and January, whereas B may linger a little bit longer until the end of April and early May. He also adds that people who get infected with influenza A will have slightly more symptoms, whereas people infected with influenza B will have some ameliorated symptoms and not get as sick.

However, colds are caused by a wide variety of viruses, including RSV (respiratory syncytial virus), rhinovirus, adenovirus, enterovirus, human parainfluenza virus (HPIV) and many others. And COVID-19 is caused by a novel virus from the coronavirus family, most specifically SARS-CoV-2.

What are Flu Symptoms Compared to Those for COVID-19 and a Cold?

The most common symptoms of these respiratory illnesses can initially present similarly. They all have varying degrees of cough, congestion, body aches, headaches, and sore throat. Flu and COVID-19 can include a fever, shortness of breath, exhaustion, and diarrhea, but the symptoms do vary with each person. Additionally, the severity and duration of the symptoms will differ with each disease.

Dr. Markou explains that symptoms of a common cold will generally be mild and resolve in 24 to 48 hours. However, the flu comes on relatively quickly after you’re infected, and the symptoms come on stronger and have a higher impact on the body. Flu symptoms will usually resolve after 5 to 7 days but can last for up to two weeks. And people will feel very sick for that duration.

In contrast, COVID-19 patients usually start showing mild symptoms within 3 to 5 days of infection, and those usually resolve in a week. These symptoms can differ for each person. For example, some people may not have a cough but exhibit diarrhea as their primary symptom. But one symptom that is more unique to COVID-19 is losing your sense of taste and smell completely. This usually resolves at some point after the virus is gone. However, sometimes in certain COVID-19 patients, there can be a reemergence of symptoms, with shortness of breath being the main concern. This type of shortness of breath and this kind of reaction is not caused by the virus per se, but more so by an overreaction of your own immune system to the virus. That’s what can get COVID-19 patients into trouble in the hospital and why they sometimes require the assistance of a breathing machine.

It is important to note that people who are fully vaccinated and then contract COVID-19, mainly due to the Delta variant currently, may exhibit different symptoms from those unvaccinated. If you do show signs and symptoms, they will likely be milder because your body has already had practice at eliminating this virus and has built up a defense.

Individuals may not experience every symptom, but any combination is common. “COVID-19 and even the common cold complicates things because of overlapping symptoms with the flu,” says Dr. Markou. “It’s crucial to really listen to your body and get tested when you’re unwell, especially as we enter the fall as a variety of respiratory illnesses are possible.”

How Do You Diagnose the Flu, COVID-19, and a Cold?

The only way to accurately diagnose if you have the flu, COVID-19, or a common cold is through testing at a doctor’s office or urgent care center. The test involves using nasal swabs that employ PCR technology. Once you have the test, the swabs go into a machine that detect DNA and RNA viral particles to provide a diagnosis of what virus you have. Different facilities have different tests, but this is the best way to diagnose if you have the flu versus COVID-19 versus a cold. It is important to know that free COVID-19 testing is available at over 400 permanent testing centers in New Jersey.

How Contagious is the Flu Compared to COVID-19 or a Cold?

The flu, COVID-19 (especially the Delta variant), and a common cold are all contagious respiratory conditions. All three spread by coughing, sneezing, or even talking. Those actions send infected respiratory droplets into the air which then get inhaled by others.

And sturdy viruses, like the flu, are also spread by touching infected surfaces as the flu viruses live much longer on them. So, you can catch the flu by touching a surface that an infected person touched after sneezing into their hand, like a doorknob. However, COVID-19 is not as sturdy a virus and doesn’t live long on surfaces, so it is much more difficult to contract this virus via contact with them. The same is true with viruses that cause the common cold. It should be noted that surface cleaners that say they “kill 99% of germs and viruses” are effective at killing viruses that live on surfaces.

Dr. Markou explains, “Infectious disease physicians like those at ID Care use a measure called the R-naught to determine the infectivity rate of the flu and other viruses like COVID-19. Essentially, the R-naught or R0 indicates how contagious and infectious a disease is, or the reproduction number. In fact, the R-naught predicts how many new cases of any given virus will replicate from exposure to a single case. For example, the R-naught for influenza is 1.3 – 1.5. That means that every infected person will infect 1.3 to 1.5 other people. In comparison, the R-naught for COVID-19 is 1.8 – 3, so it’s significantly more contagious than the flu. However, there is not an exact R-naught available for a cold, but it’s less than 1 for most cold viruses, so they are not as infectious. So COVID-19 is the most contagious, followed by the flu, and then a cold. And it is easy to see how these numbers scale, and how the COVID-19 pandemic arose and why the upcoming flu season is a concern”.

Who is Most at Risk for Flu Complications Compared to COVID-19?

Anyone can get sick from the flu or COVID-19, but there are populations that are more at risk. For the flu, it affects extreme ages – very young babies and children to older adults over 65. Additionally, those with comorbid underlying health conditions, including diabetes, obesity, and heart, lung or kidney disease are at higher risk for both viruses. Up until recently, the flu affected far more children and babies than COVID-19. However, the Delta variant is now affecting children at a higher rate than previous COVID-19 strains and has presented challenges in certain states where they have run out of pediatric ICU beds due to higher volumes of severe cases.

Can You Get Hospitalized or Die from the Flu?

Although most people recover from the flu within two weeks, it’s possible to be hospitalized if you’re considered higher risk and showing signs of not breathing well. The flu can be quite severe and should be taken seriously. Dr. Markou explains, “In fact, a person who comes to the doctor or ER and their oxygen levels are dropping, appear to be severely dehydrated, or have uncontrollable fevers, oftentimes, the ER or internal medicine doctor who is working at the hospital will admit them for evaluation”.

The CDC estimated 400,000 flu-related hospitalizations and 22,000 deaths in the 2019/2020 season. The upcoming flu season is expected to be more difficult as we now must factor in COVID-19 and related hospitalizations and deaths. The best way to prevent hospitalization is to get diagnosed by a doctor at the onset of symptoms and to determine the proper course of treatment.

How Can You Prevent the Flu, COVID-19, or a Cold?

You can prevent or minimize symptoms for the flu, COVID-19, or a cold with frequent hand washing, physical distancing, covering coughs and sneezes, limiting exposure to infected people, and staying home when you’re sick. Additionally, vaccinations for both the flu and COVID-19 are beneficial immune-building tools that help your body develop antibodies and protect you from these viruses. These vaccines protect you from becoming ill or significantly lessen your symptoms if you do become infected. Currently, a vaccine for the common cold doesn’t exist. “Taking preventative measures, including getting vaccinated, is important for everyone who is eligible,” says Dr. Markou. “Babies under 6 months cannot get a flu shot and kids under 12 years old can’t get a COVID-19 vaccine, so a great way to protect them is try to surround them with people who are inoculated.”

What Flu and COVID-19 Vaccines are Available?

There are several flu and COVID-19 vaccines available today. While they each work differently, they all serve to create antibodies to fight the virus and are highly effective in preventing infection or minimizing the symptoms of these contagious respiratory illnesses.

It is recommended that everyone 6 months and older get their flu shot each year by early October, prior to the onset of flu season. And if you’re also getting a COVID-19 vaccine (now available for children 12 years and older), Dr. Markou recommends waiting a two-week period between getting a flu vaccine and COVID-19 vaccine.

Flu Vaccines and How They Work?

There are three main types of flu vaccines and each one creates antibodies in a different way. Each year, WHO (World Heath Organization) collects data to predict flu strains that will be most prevalent, and vaccines are formulated to specifically address these strains. The following highlights the flu vaccines available and how they work.

  • Fluzone – this vaccine is the most used and is made up of a dead or inactivated The immune system is exposed to pieces of it and develops antibodies to protect you from a new infection. This vaccine is injected into the arm and used for people 6 months of age and older. There are two doses of this vaccine; the normal dose and a higher dose version that is optimal for those over 65 as it provides more protection.
  • FluMist – this vaccine takes a live attenuated virus and weakens it. Once introduced, it causes an immune response in the body. This vaccine is given as an intranasal spray and is approved for people 2 to 49 years old. This vaccine should not be administered to those pregnant, immunocompromised, or have other select health conditions.
  • Flublok – this vaccine is the newest and produced through recombinant or synthetic technology. It takes proteins from the influenza virus itself and formulates a vaccine using those proteins, so your body recognizes and makes more of those proteins. This creates antibodies for protection from infection. This vaccine is injected into the arm. CDC studies show the recombinant vaccine provides better immunity for seniors. Flublok is recommended for individuals 18 years and older, including those with egg allergies.

It should be noted that all these vaccines are approved and tested for safety. Individuals may experience minor side effects from the flu vaccine, including a low-grade fever or sore arm, but these will go away within a few days. It is vital to get the flu vaccine for protection again the influenza virus. An ID Care infectious disease expert can assist in determining what vaccine is optimal based on your age, health status, allergies, and other key factors. They can also administer the Fluzone vaccine in preparation for flu season.

COVID-19 Vaccines and How They Work

There are two primary types of COVID-19 vaccines available. The mRNA technology vaccines are available from both Pfizer-BioNTech and Moderna as a two-dose base regimen while the more traditional virus-based technology is used for the single dose Johnson & Johnson vaccine. Only the Pfizer vaccine is now FDA approved, while the other vaccines are still available under EUA (Emergency Use Authorization) as they are pending FDA approval. It is important to note that no COVID-19 vaccine has any active virus as part of its composition, nor does it interact with or impact your DNA in any way.

  • mRNA Technology – messenger RNA (mRNA) vaccines do not alter your DNA.
    The vaccine works by taking a piece of viral mRNA material and placing it into a fat molecule.  This fat molecule is then taken up by cells to produce the protein encoded by the viral code (mRNA material). The protein will be recognized by your immune system and develop antibodies to protect you from infection. The cells teach your body how to make the protein found on the surface of the COVID-19 virus. That causes your body to create antibodies to protect you from infection. The two doses for this vaccine are administered in the arm at different time intervals about a month apart. For the Pfizer vaccine, it is FDA approved for those 16 and older but its EUA extends to ages 12-15, while Moderna is cleared for those 18 and older.
  • Traditional Virus-Based Technology – this vaccine uses a weakened version of an adenovirus, which is a group of viruses that create cold-like symptoms. The virus enters your cells and is translated into a protein that forms a large structure with protruding bumps, known as a spike protein. Spike proteins are what help any type of coronavirus (including COVID-19) infect cells. In this case, the spike protein is shown to your body to create antibodies. That prevents the COVID-19 virus from being able to latch onto your cells and infect you. This is a single-does vaccine administered in the arm. This vaccine is cleared for those 18 and older.

According to Dr. Markou, “It’s important to note that people who are fully vaccinated and then contract COVID-19, mainly due to the Delta variant currently, may exhibit different symptoms from those unvaccinated”.  Those vaccinated are more likely to experience upper respiratory symptoms such as runny nose, headache, fatigue, loss of smell/taste, sinus congestion and less likely to experience high fevers, cough, and shortness of breath.

For information on convenient NJ locations to access all COVID-19 vaccines, visit the New Jersey COVID-19 Information Hub.

How Does ID Care Treat Flu Patients?

ID Care physicians are experts at preventative measures as well as treating flu patients. First, they recommend the flu shot as a preventative step. It’s available at all 10 ID Care locations. If you’ve already been infected with the flu, ID Care’s infectious disease doctors will evaluate your condition and may prescribe an antiviral medication called Tamiflu (oseltamivir). The prescription antiviral is most effective when started within 48-72 hours of infection, decreasing the severity of symptoms and the amount of virus in the body so you recover faster.

How Does ID Care Treat COVID-19 Patients?

The infectious disease experts at ID Care are working inside New Jersey’s hospitals, nursing homes, and other healthcare facilities to care for and treat hospitalized COVID-19 patients. In fact, they have guiding response to the COVID-19 pandemic across the state during the last year and a half. They continue to lead measures for infection control and new treatment protocols that are on the forefront of the COVID-19 pandemic – saving lives and improving outcomes for patients.

ID Care Infectious Disease Experts for Respiratory Illnesses

The many overlapping symptoms between the flu, COVID-19, and the common cold can be confusing. That, coupled with the infectious nature of all three, make it important to stay home and get tested when you’re sick. The promising news, however, is that there are steps you can take to prevent infection or minimize the severity of illness. They include getting fully vaccinated for COVID-19 and influenza as well basic measures like mask wearing in crowded spaces, physical distancing, practicing good hand hygiene, and covering your mouth and nose when sneezing or coughing.

As the largest infectious disease practice in New Jersey and the second largest in the country, the ID Care team are leaders in the prevention and treatment of any type of infectious disease, including the flu and COVID-19. To learn more, visit idcare.com or call 908-281-0610 to schedule an appointment with an ID Care infectious disease expert.

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