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Genetic Typing Could Answer Key Questions in COVID-19 Tort Litigation

Genetic Typing Could Answer Key Questions in COVID-19 Tort Litigation

By Adam M. Dinnell

As the coronavirus pandemic engulfs us, it is easy to imagine the litigation that may follow—including tort suits seeking damages for illness or death allegedly caused by negligent or reckless exposure. Possible fact patterns could run the gamut, from a business carelessly allowing a sick employee to interact with customers to a healthcare facility taking inadequate steps to protect patients, or an individual refusing to isolate from others in spite of obvious symptoms.

Causation in such cases will hinge on proof that the plaintiff did (or did not) contract the coronavirus from the alleged source. But how can you pinpoint the actual source when every form of human contact, consistent with the incubation period, may be an exposure pathway? And for defendants, how can you persuade a jury—particularly in the face of culpable conduct—that even though the plaintiff contracted the coronavirus, he or she contracted it elsewhere? Part of the answer may lie in genetic sequence-based typing.

Genetic typing, also known as molecular typing, is a form of genetic “fingerprinting” or “barcoding” that can differentiate between potentially thousands of different genetic types of a particular pathogen (e.g., a virus or bacterium).[1] If samples are collected and preserved, a microbiologist can identify the genetic sequence of the pathogen that afflicted a patient, type that sequence, and compare it to other recorded sequences for a possible genetic match. This matching process allows scientists to draw conclusions about how someone may have contracted the illness. For example, similar typing results between two patients may support the possibility of direct transmission or a shared exposure source. Results showing different genetic sequence types can be used to rule out a connection.

Scientists have already succeeded in identifying the complete genome sequence for SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19).[2] The virus consists of a single, positive-stranded RNA that is roughly 29,000 nucleotides long (whereas the human genome is over 3 billion).[3] While early samples associated with Wuhan, China were genetically similar,[4] the genetic sequence of SARS-CoV-2 will steadily mutate over time as the virus continues to spread.[5] This diversification will aid in the identification of transmission chains as potentially hundreds or even thousands of unique sequence-types emerge.[6] As sequence-types are catalogued, sections or sequences of the genetic code can be recorded and compared with those of other samples.

The use of genetic sequence-based typing evidence in litigation is not unprecedented. Similar evidence has already been used as part of a successful motion for summary judgment in a case involving another respiratory illness, Legionnaires’ disease (pneumonia caused by Legionella bacteria).[7] As the defendant’s microbiologist explained in her supporting affidavit, “In layman’s terms, this [genetic typing] method assigns a “barcode” for each Legionella pneumophila isolate . . . When two isolates have different [genetic typing] profiles, the isolates are unlikely to be associated with each other in an epidemiological context.”[8] Using this genetic typing evidence, the defendant was able to show that the specific Legionella sequence type that afflicted the plaintiff (ST 224) did not match the sequence type present at the defendant’s healthcare facility during a highly publicized outbreak (ST 1395).[9] This, in turn, showed that defendant was not the cause-in-fact of plaintiff’s illness.

Similar cases show the utility of genetic typing and matching in pathogen cases. In a case involving E.coli bacteria, the specific strain of bacteria that sickened plaintiffs (O157:H7) was identified by government scientists and found to be the genetic match of a strain found on meat products manufactured by a particular meat fabricator.[10] In denying a related Daubert challenge on causation opinions, the court found that the genetic evidence on its face constituted “a sufficiently reliable basis, in the form of both microbiological and epidemiological findings,” for expert testimony.[11]

In a case involving the Hepatitis C virus, a court denied a challenge to the use of the public health department’s genetic typing analysis concluding there was a genetic match between the virus plaintiff contracted and that of a preceding patient at defendant’s facility. This was despite the analysis being based on a limited comparison of a small portion of the virus genome.[12] Another court has also remarked favorably on the value of this type of scientific causation evidence. In a case involving the PRRS virus, the court emphasized that a veterinary expert had testified that the genetic type of the virus found at a defendant’s hog farm was 99% identical to that found at plaintiff’s farm.[13]

Other cases support the basic concept that testing data may be required to establish proof of relevant exposure and causation in coronavirus cases. In a case involving Histoplama capsatum fungus, an appellate court affirmed summary judgment on no causation where plaintiff failed to come forward with any objective evidence that the fungus that afflicted plaintiff was ever found at the defendant’s chicken coops.[14]   This was despite the plaintiff being able to prove regular contact with the chicken coops and that chicken coops are generally a known source of the fungus.[15]

Even where there is proof plaintiff was exposed to a person or place hosting coronavirus, this may still not be enough where more specific identification methods are available (e.g., evidence concerning whether the same genetic type of coronavirus afflicted both plaintiff and the alleged defendant-source). In a case involving MRSA bacteria, the court granted summary judgment for defendant where, among other deficiencies, plaintiff could not rebut evidence there were no cases linked to defendant through “molecular typing of MRSA strains.”[16] Any suggestion of causation was, thus, sheer speculation. In a case involving Listeria bacteria, a court granting summary judgment for plaintiffs also remarked on the importance of scientific identification evidence—emphasizing the weight of testing evidence that showed the unique strain of Listeriosis afflicting plaintiffs matched the outbreak strain found on defendant’s turkey products.[17]

Tips for Practitioners

Future cases involving the coronavirus may hinge on this type of identification evidence more than ever before. Where every form of contact is a possible source of exposure, scientific fingerprinting methods like genetic sequence-based typing will become crucial to linking or ruling out an alleged source as the cause-in-fact of a plaintiff’s illness. Practitioners facing the prospect of future COVID-19 tort litigation should start preparing now.

1. Practitioners should engage the scientific aspects of the coronavirus as soon as possible. This includes reading relevant scientific and medical literature and researching the basic concepts behind genetic typing. Acquiring a basic understanding of the science involved will be key to effectively presenting this evidence to a judge or jury.

2. As potential suits emerge, practitioners must emphasize the importance of obtaining and preserving any samples (e.g., from sputum or nasopharyngeal/oropharyngeal swabs) to clients, clients’ healthcare providers, and public health departments. Practitioners should also put all potential parties on notice that any samples within their possession, custody, or control must be preserved to avoid spoliation. Third parties such as public health departments that may possess relevant samples or sample testing data should also be contacted to make sure no evidence is lost or destroyed. It is self-evident that if a patient’s sample of the virus is not preserved, there will be nothing to type, no fingerprint to compare against potential matches, and possibly insufficient evidence to prove or disprove plaintiff’s allegations.

3. As informed by experience in similar cases, practitioners should engage top experts in microbiology and virology as soon as possible to win the potential arms race that may follow. While the use of genetic typing continues to grow, there remains a finite number of experts with the requisite technology and experience.

Although uncertainty surrounding the pandemic reigns, an understanding of new age scientific evidence such as genetic typing will be crucial to being ready for the litigation that is to follow.

[1] See generally, Molecular Typing,

[2] E.g., Sah R, Rodriguez-Morales AJ, Jha R, Chu DKW, Gu H, Peiris M, Bastola A, Lal BK, Ojha HC, Rabaan AA, Zambrano LI, Costello A, Morita K, Pandey BD, Poon LLM. 2020. Complete genome sequence of a 2019 novel coronavirus (SARS-CoV-2) strain isolated in Nepal,

[3] Id.; Bad News Wrapped in Protein: Inside the Coronavirus Genome,

[4] Id.

[5] Software and Genetic Sequencing Track the Coronavirus’s Path,

[6] See GenBank, SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) Sequences,; Nextstrain,

[7] Schultz v. United States, 2017 WL 635289, at *5 (W.D. Pa. Feb. 16, 2017).

[8] Declaration of Natalia Kozak-Muiznieks, Ph.D., 2016 WL 9410655 (for a sample of the evidentiary support required for this type of argument).

[9] Schultz, 2017 WL 635289, at *5 (although granting summary judgment before reaching causation issues, recognizing that, “The strain in Mr. McCluskey’s sample was ST 224, a strain that has never been found at the VA hospital.”).

[10] Long v. Fairbank Farms, Inc., 2011 WL 2516378, at *2-3 (D. Maine May 31, 2011).

[11] Id.

[12] Gonzalez v. Arya, MD, 2013 WL 12094285 (N.Y. Sup. Nov. 3, 2013).

[13] TDM Farms, Inc. of North Carolina v. Wilhoite Family Farm, LLC, 969 N.E.2d 97, 107 at n.5 (Ind. App. 2013).

[14] Krishack v. Milton Hershey Sch., 145 A.3d 762, 766-68 (Pa. Super. Ct. 2016) (emphasizing there were other possible routes of exposure and plaintiff had no proof through soil testing or otherwise that the fungus was ever found on the defendant’s premises).

[15] Id.

[16] Frederick v. Intercontinental Hotels Group Resources, Inc., 2011 WL 666843, at *8 (E.D. La. Feb. 14, 2011).

[17] Drayton v. Pilgrim’s Pride Corp., 472 F. Supp. 2d 638, 639 (E.D. Pa. 2006).