Three Reasons Legionella Bacteria Sampling is Important During the COVID-19 Pandemic

By: Hilary Nardone, Environmental Group Training Manager
Certified ASSE 12080 Legionella Water Safety and Management Specialist

Routine Legionella bacteria sampling continues to be an important tool during the COVID-19 pandemic to minimize your facility’s risk of Legionnaires’ disease. Below are three reasons why your facility should be routinely sampling for Legionella bacteria during this time:

1. Legionnaires’ disease and COVID-19 have similar symptoms

Legionnaires’ disease and COVID-19 share similar symptoms, such as cough, shortness of breath, fever, muscle aches, and headaches.1,2 While in the midst of the COVID pandemic, an individual with Legionnaires’ disease could easily be suspected of having a SARS-CoV-2 infection resulting in delayed Legionnaires’ disease treatment. Because Legionnaires’ disease is contracted by inhaling and aspirating Legionella bacteria-contaminated water droplets, minimizing the presence of those bacteria can lessen the chances of someone becoming ill with Legionnaires’ disease. By proactively testing for Legionella bacteria and implementing remediation strategies on positive samples, your facility can reduce the risk of a person contracting Legionnaires’ disease, minimizing the chances of a misdiagnosis.

2. COVID-19 infections can predispose patients to Legionnaires’ disease

Immunocompromised persons are at an increased risk of becoming infected with Legionnaires’ disease.Those who are sick from or have recovered from COVID-19 may be immunocompromised and more vulnerable to other bacteriological diseases. According to a paper by Dey and Ashbolt, COVID-19 infections can “predispose patients to Legionella co-infections…and consequently pose a serious threat to high-risk COVID-19 patients…which can lead to an increase in disease severity and mortality.”Testing for Legionella bacteria at your facility can reduce a person’s risk of contracting Legionnaires’ disease, even after they have recovered from COVID-19.

3. Stagnant water in facility plumbing systems can amplify Legionella bacteria

Facilities that have been closed or running at reduced occupancy during the pandemic risk stagnant water conditions and the potential for increased levels of waterborne pathogens, including Legionella bacteria. In addition to following the CDC’s latest guidelines for ensuring the safety of your building water systems components after a period of prolonged shutdown, testing for Legionella bacteria in your facility can help validate water quality.

Contact Barclay for your Legionella bacteria sampling needs. Barclay offers sampling and testing programs to detect Legionella bacteria in potable and non-potable water systems and we provide the results along with result interpretations and relevant recommendations. Barclay’s third-party laboratory is accredited by the CDC ELITE Legionella Program. Barclay continually recommends sampling and remediation best practices and strategies from organizations including but not limited to ASHRAE, CDC, OSHA, and state and local Health Departments.


1. CDC.Legionella (Legionnaires’ disease and Pontiac fever): Signs and symptoms.CDC.Updated April 30, 2018.Accessed January 28, 2021. https://www.cdc.gov/legionella/about/signs-symptoms.html
2. CDC.COVID-19: Symptoms of coronavirus.CDC.Updated December 22, 2020.Accessed January 28, 2021. https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html
3. CDC.Legionella (Legionnaires’ disease and Pontiac fever): Causes, how it spreads, and people at increased risk.CDC.Updated January 15, 2020.Accessed January 28, 2021. https://www.cdc.gov/legionella/about/causes-transmission.html \
4. Dey R, Ashbolt NJ.Legionella infection during and after the COVID-19 pandemic.ACS ES&T Water. 2020. Doi: 10.1021/acsestwater.0c00151 .

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