Get the latest COVID-19 information: vaccines, testing, getting care and more
Doctor's office
Enter your doctor's name to get office information.
Find labs in your network
Enter your primary care doctor's name to find labs in your network.
Find urgent care centers in your network
Enter your primary care doctor's name to find urgent care centers in your network.
Verify your medical group

Refer to your insurance card or call your insurance provider to determine your medical group.

You can also search for your primary care doctor to find the medical group you and your doctor belong to.

Driving Directions
Update Information
Forgot Password

Please enter your e-mail address.

Sharp Health News

Does the flu make you more susceptible to COVID-19?

Sept. 3, 2020

Does the flu make you more susceptible to COVID-19?
In the midst of dealing with a pandemic, it’s hard to believe that the flu season will soon be upon us. This realization leaves some worrying that the two respiratory illnesses could hit like a one-two punch, causing more — and possibly more severe — illness.

COVID-19 and the flu are similar in some ways, but are caused by different viruses. Both flu and COVID-19 are spread from person-to-person and can cause varying illness from mild to severe. They also share some symptoms, including:

  • Fever or feeling feverish/chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Sore throat
  • Runny or stuffy nose
  • Muscle pain or body aches
  • Headache
  • Vomiting and diarrhea (more common in children than adults)
While the CDC reports that COVID-19 is proving to be more deadly than the seasonal flu, especially for older adults and people with underlying health conditions, the flu can be more dangerous for children. However, there is still much to be learned about COVID-19, including whether having the flu makes you more susceptible to being infected by the novel coronavirus that causes the disease, and whether having both at the same time might lead to more severe illness.

The risk of dual diagnosis
“Although there is no clinical evidence so far to suggest that one viral infection, such as influenza, increases susceptibility of being infected by another virus, such as the novel coronavirus that causes COVID-19, it is plausible to suspect that people can be infected by both at the same time,” says Dr. Hai Shao, a board-certified infectious disease specialist affiliated with Sharp Chula Vista Medical Center. “The cell tropism, which are the cells and tissues in your body that support growth of a particular virus or bacteria, and cell surface receptors that induce changes in cell activity are different for each virus.”

Even more concerning, according to Dr. Shao, is that both viruses target and damage the respiratory tract, primarily while stimulating a robust immune response. The risk of having more severe symptoms and severe complications caused by dual infection, such as acute respiratory distress syndrome (ARDS), multi-organ system failure, or sepsis and subsequent bacterial pneumonia, is conceivably higher.

Other common respiratory symptoms — nasal congestion, runny nose, sore throat and productive cough — might also be increased in severity. And the duration of the symptoms, both mild and severe, could be longer.

The upside of flu season during the pandemic
The good news is that the precautions we have been taking for several months to decrease the spread of COVID-19 — hand-washing, wearing face coverings and social distancing — can also decrease the risk of getting the flu. This is because both viruses spread and transmit via respiratory droplets when people who are infected breathe, speak, cough and sneeze.

“Current public health measures would significantly decrease the risk of viral transmission for other common cold viruses as well as influenza,” Dr. Shao says. “It is widely predicted that if people are following guidance of public safety for COVID-19 prevention, we could have a much milder season for influenza this year.”

In addition to preventive steps to slow transmission of both illnesses, Dr. Shao and colleagues stress that the flu shot and vaccination against COVID-19 — when available — is still pivotal to achieve herd immunity and significantly decrease both infections in the community.

“People age 6 months and older should get the flu vaccine as directed by their health care providers,” Dr. Shao says. “And once a scientifically proven, safe and effective vaccine for COVID-19 is available, we should get vaccinated as soon as possible.”

For the news media: To speak with Dr. Shao for an upcoming story, please contact Erica Carlson at

You might also like:

Choose the doctor who's right for you.

At Sharp, we make it easy to find an exceptional doctor — right where you live and work.

All Categories
Contact Sharp HealthCare
Call us

Call 1-800-827-4277 or view our detailed phone directory.

For medical or psychiatric emergencies, call 911 immediately.

Email us

Please do not use this form to convey personal or medical information.

How would you like to be contacted?
Date of birth

What's This?

These important numbers are located on your billing statement.

Find your Sharp Rees-Stealy account number

Find your SharpCare account number

Find your SharpCare account number
What's GDPR?

The General Data Protection Regulation (GDPR) governs the processing of personal information gathered from individuals while they are in the European Union (EU) and parts of the EEA (European Economic Area, which currently includes Iceland, Lichtenstein and Norway).

We are sorry, but we are unable to process your price estimate if you live or are travelling within the EU or affiliated nations.

What's This?

Many surgery and procedure names sound similar. If possible, please provide the current procedure terminology (CPT) code, which can be found on the order from your doctor.

If you cannot provide the CPT code, please contact your doctor's office for the CPT or a detailed description of services.