Contributed Commentary by Felisha Pierre-Louis and Konrad Knauss
May 24, 2021 | Diagnostic testing continues to play a vital role in protecting public health throughout the COVID-19 pandemic. To date, we have seen how rapid and reliable diagnostic testing has enabled early identification of COVID-19 cases to ensure patients receive timely and appropriate treatment. At the same time, governments and public health agencies have been relying on diagnostic testing to save innumerable lives by reducing onward transmission of the SARS-CoV-2 virus through prompt isolation and tracing efforts. This has been particularly important when it comes to asymptomatic patients, for whom a positive test is the only indication of infection.
In the media, much of the focus on COVID-19 testing workflows has, rightly, been on the ability of diagnostic laboratories to meet public health demand. However, we should not overlook the importance of using workflows that safeguard the health of medical laboratory personnel by preventing potential exposure to the SARS-CoV-2 virus. This is of utmost significance given the high volume of tests processed every day, increasing the risk to laboratory teams.
Virus Inactivation: A Critical Component of COVID-19 PCR Testing
Since the COVID-19 outbreak in February 2020, two types of diagnostic tests have been widely used to determine active infections—antigen testing and polymerase chain reaction (PCR) testing. Antigen tests detect protein fragments specific to the SARS-CoV-2 virus and offer rapid results, usually within 15 minutes. PCR tests, on the other hand, identify the virus RNA, and while they have longer turnaround times (typically 24–72 hours), they generally produce fewer false-positive results. As such, PCR tests are currently the more popular of the two approaches.
To support safe sample handling and protect medical laboratory personnel from infection during PCR testing workflows, it is necessary to perform the key step of virus inactivation. While several methods exist for virus inactivation—including the use of detergents and ultraviolet light—many laboratories prefer the application of heat to COVID-19 samples to inactivate the SARS-CoV-2 virus in PCR workflows. Studies recommend that specimens are heated to temperatures of between 56 °C and 65 °C for at least 30 minutes to deactivate the virus (DOI: 10.1016/j.jviromet.2004.06.006), with temperatures of approximately 65 °C favored by several recent papers.
When inactivating samples, care must be taken to avoid overheating them as this can reduce the quantity of the detectable virus RNA, which can lead to false-negative test results. At the same time, underheating samples risks incomplete virus inactivation, putting the health of laboratory professionals in danger. To ensure safe and effective virus inactivation by heat, precise temperature control is essential.
Advanced High-End Microbiological Incubators: Safe and Reliable Virus Inactivation
Among the most reliable and widely used technologies for virus inactivation are advanced high-end microbiological incubators, which offer a controlled, contaminant-free environment by regulating conditions such as temperature.
In contrast to conventional heating options, such as laboratory ovens which operate over a very broad range of high temperatures (typically 50–330 °C), modern high-end microbiological incubators provide very precise temperature control over a more focused range of moderate temperatures (between 27–105 °C). This enhanced control means these systems provide very little room for temperature drift (usually just a tenth of 1 °C), ensuring superior uniformity and stability of virus inactivation conditions.
Ongoing Advances in Sample and Personnel Protection
While precise temperature control is critical for reliable virus inactivation, it is not the only aspect of high-end microbiological incubator design that is important for ensuring sample and laboratory personnel protection.
Consider sample loading and unloading, for example. In routine use, laboratory teams will transfer batches of test samples in and out of the incubator chamber many times each day. Ask any scientist or technician who has accidentally left an incubator door open for more than a few minutes, and they will tell you how important it is that this changeover happens as quickly as possible to prevent a large amount of heat from escaping. Not only is this type of incident extremely inefficient—requiring the unit to re-heat to reach the appropriate temperature—it also risks uneven temperature distribution within the chamber, leaving samples vulnerable to incomplete virus inactivation.
Fortunately, equipment vendors have responded to this need by developing advanced high-end microbiological incubators that incorporate innovative features to enhance sample protection, such as open-door warning systems and audible alarms that alert users to internal temperature deviations. Some modern systems also feature secure, lockable doors that can be used to restrict access from unauthorized individuals, further supporting the integrity of samples and test results.
Other improvements in incubator design are enabling more efficient aseptic sample handling procedures, which are vital for the protection of laboratory professionals. Here, a clear trend is toward making high-temperature chamber decontamination cycles as convenient to incorporate into workflows as possible. Some high-end microbiological incubators, for example, offer push-button, rapid decontamination cycles, facilitating fast turnaround times and continuous operation. By minimizing exposure to virus contamination while making PCR workflows easy to use, these advanced solutions are efficiently securing the integrity of test results and laboratory safety.
Safeguarding Samples, Personnel and Public Health
The COVID-19 pandemic has placed unprecedented demands on the diagnostic laboratories and scientific professionals tasked with protecting our health. Without robust and reliable workflow methods for the handling of PCR test samples, each new specimen potentially puts the safety of these vital teams at risk. Recognizing this need, technology innovators have responded by developing high-end microbiological incubators that not only provide the precise temperature control necessary for effective virus heat inactivation, but also incorporate advanced design features that enhance laboratory safety and usability. By strengthening the integrity of PCR workflows, these advanced technologies are helping diagnostic teams continue their work to protect public health, in the safest possible laboratory environment.
Felisha Pierre-Louis is a Sr. Product Manager for incubation equipment at the Laboratory Products Division of Thermo Fisher Scientific. She holds an MBA from Harvard Business School and a BA from Cornell University. She can be reached at Felisha.pierre-louis@thermofisher.com.
Konrad Knauss is a Product Manager for heating equipment at the Laboratory Products Division of Thermo Fisher Scientific. With a business degree from Mannheim University and an MBA from York University, Konrad has 15 years of experience in the industry and has overseen almost all aspects of managing products for heating, drying and incubation purposes.