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Long COVID, also known as post-acute COVID-19 syndrome (PASC), is a condition where people experience symptoms of COVID-19 for weeks, months, or even years after their initial infection. The symptoms can be mild or severe, and can affect any part of the body. The World Health Organization (WHO) defines Long COVID as “the continuation or development of new symptoms 3 months after the initial SARS-CoV-2 infection, with these symptoms lasting for at least 2 months with no other explanation.”

Roughly 25 million people in the U.S. and over 17 million people in Europe have long COVID symptoms, with many more in other parts of the world.

The Workers’ Compensation Insurance Rating Bureau of California (WCIRB) has released an updated COVID-19 report, Medical Treatments and Costs of COVID-19 Claims and “Long COVID” in the California Workers’ Compensation System – 2023 Update. The study provided an early assessment of the prevalence of “long COVID” (post-acute sequelae of SARS-CoV-2 infection, PASC) in the workers’ compensation system. The study estimated that approximately 11% of COVID-19 claims with an initial mild infection received medical treatment for long COVID symptoms over a 4-month post-acute care period. The rate of long COVID spiked to about 40% for those hospitalized for the initial infection.

A recent study from the Workers Compensation Research Institute (WCRI) found that 7 percent of workers with COVID-19 claims received treatment for long COVID after the acute period of the infection. While long COVID prevalence was the highest among workers who were hospitalized during an acute stage of disease, even some workers with limited medical care early after the infection developed long COVID symptoms.

For these Long COVID cases, the claim administrator will likely need to resolve the permanent disability component, and apportionment. Labor Code § 4663(a) provides that “(a) Apportionment of permanent disability shall be based on causation.” That begs the question about causation of Long COVID under this standard. Perhaps a newly published study by the Genome-wide Association Study of Long COVID is a good start at an answer.

The COVID-19 Host Genetics Initiative (COVID-19 HGI) ) was launched to investigate the role of host genetics in COVID-19 and its various clinical subtypes. It also conducted the first genome-wide association study (GWAS) specifically focused on Long COVID. This part of the study includes data from 24 studies conducted in 16 countries, totalling 6,450 individuals diagnosed with Long COVID and 1,093,995 controls.

The new research, which was an international collaboration between dozens of scientists, describes how some people carry a version of a single gene, FOXP4, that is associated with developing long COVID. FOXP4 has been previously associated with COVID-19 severity, lung function, and cancers, suggesting a broader role for lung function in the pathophysiology of Long COVID.

Conversely, scientists estimate that over 20% of people who get infected with COVID never have any symptoms – and a portion of them never even know they were infected. Now a new study published in Nature on July 19 says their genetics might be why the virus didn’t make them sick.

Some people have a version of a gene in their immune system called HLA-B that protects them from feeling the effects of the virus. The study found that people with this special HLA-B variant are 2 to 8 1/2 times more likely to be asymptomatic than those without the variant.

Jill Hollenbach, an immunologist at the University of California, San Francisco, was one of the scientists who led the research on asymptomatic COVID. She says she was “surprised and excited” about the new long COVID findings.

“The fact that the authors were able to detect this association [between the FOXP4 gene and long COVID], I think, is spectacular,” Hollenbach says.

Dr. Hollenbach would obviously be a local expert to consult for further information on possible apportionment in a claim for permanent disability in a Long COVID case.