Sick woman sitting on bed with blanket over shoulders as she blows her nose into a facial tissue

COVID-19 and the flu are not the same

Even with more than 4.6 million deaths worldwide and 700,000 in the United States, the notion persists that COVID-19 is just another flu.

Not true, said Mark Meeker, DO, vice president of Community Medicine at OSF HealthCare. The novel coronavirus known as SARS-CoV-2, which causes COVID-19, is significantly different from influenza.

“It’s a highly contagious virus, and it’s a much deadlier virus in certain populations,” Dr. Meeker said.

Major differences between flu and COVID-19

It might seem like the flu and COVID-19 are the same, but there are three symptoms more specific to COVID-19.

There are many similarities between COVID-19 and the flu. Both attack the respiratory system and present the same type of symptoms, such as fever, cough, sore throat and congestion.

COVID-19 also can be marked by breathing difficulty, loss of taste and smell, nausea, vomiting and diarrhea. It attacks the respiratory and neurological systems (lungs and brain), as well as the heart, kidneys and other organs.

The flu and COVID-19 differ in additional ways.

“When COVID-19 starts to come on, it may seem mild,” Dr. Meeker said. “Then five to eight days later, it can start to intensify.

“It tends to create a much more intense inflammatory response in the body. The virus can overwhelm the system, causing blood clotting and scarring. It can have some really long-lasting effects, particularly for those individuals who get the most ill.”

Influenza can overwhelm a person, too, and even land them in the intensive care unit (ICU).

“In patients with COVID-19 and specific risk factors or older age groups, we can see weeks on end of needing ICU care, and then ultimately, lives are sometimes lost. In these populations, the sickest of the sick have a severity of illness more frequent and severe than what we tend to see with influenza.”

Influenza can also kill, but the mortality numbers are exponentially smaller than COVID-19 deaths. Dr. Meeker said an estimated 28,000 Americans died from influenza during the 2018-19 flu season. That’s about 14% of the number who died during the first six months of the pandemic.

“The 2019-2020 influenza season was like no other in recent history, with very few cases, likely as a result of all the COVID precautions put in place,” Dr. Meeker said.

Herd immunity takes time

masked husband takes his wife's temperature on the couch with the family dog in their laps

Influenza is contagious and can be deadly, but society at large is able to cope because the illness has been around for a long time. Dr. Meeker notes the flu pandemic of 1918-20, which killed an estimated 50 million worldwide and nearly 700,000 in the United States. Over the past 100 years, the medical science community has learned a lot about influenza.

People who become infected with a virus create antibodies that help them fight off future infections. Vaccines induce a similar antibody response. The combination limits the number of people the virus can infect, reducing opportunities for it to spread. This creates the phenomenon known as “herd immunity.” There is also good data that shows antibodies from immunization lessen the severity of a disease if a vaccinated person does contract COVID-19.

Dr. Meeker said the percentage of the population acquiring individual immunity needed to reach herd immunity is difficult to pinpoint, but it likely exceeds 75-80%.

“When you combine immunity that people in the U.S. have acquired from infection and the vaccines that were introduced in late 2020/early 2021, we are hopefully getting much closer to that herd immunity level,” Dr. Meeker said. “But with new COVID-19 variants now circulating around the world, it’s more important than ever to get vaccinated and not take the chance of waiting to develop immunity through infection.”

Protect yourself and your community

We know that COVID-19 is highly contagious and potentially deadly. This is especially true for older people and individuals with underlying health problems. It also leaves some people with long-lasting health complications.

And, unlike influenza, it can be spread by infected people who never get symptoms.

“COVID-19 just spreads faster because it can,” Dr. Meeker said. “We have seen that one or two individuals in a community quickly turns into 10 to 15, and that 10 to 15 into a thousand and so on.”

Meanwhile, as COVID-19 and its variants continue to march, we are once again entering the flu season.

You can help minimize the impact on your community by getting a flu shot and following the basic steps to minimize the spread of COVID-19:

  • Get the COVID-19 vaccination
  • Practice good hand hygiene.
  • Maintain physical distancing (at least six feet) when appropriate.
  • Stay home if you’re sick.
  • Wear a mask indoors when required by state or local authority.

Last Updated: October 7, 2021

About Author: Kirk Wessler

After being a writer for OSF HealthCare for three years, Kirk Wessler retired in January 2022. A Peoria native and graduate of Bradley University, Kirk's experience included working for newspapers in Missouri, Texas and the Peoria Journal Star.

Kirk and his wife, Mary Frances, have five sons, four daughters-in-law and nine grandchildren. Kirk plans to spend his retirement on the golf course, mastering the guitar and traveling.

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Categories: COVID-19, Preventive Health