The COVID-19 pandemic that started in 2019 will be felt worldwide for decades to come even after the infections are brought under control. The United States has been especially hard-hit. In the midst of the pandemic, clinicians, researchers and policymakers are focused on immediate concerns: the number of cases and deaths; health care capacity; personal protective equipment inventories; and social distancing and other mitigation efforts, the economic and other consequences of these efforts, and when we can safely end them.
But there are longer-term questions that the world will need to answer in order to recover and plan for the future. Much of the epidemiology and natural history of COVID-19 is still poorly understood, especially as seroprevalence surveys indicate that large proportions of infected individuals are asymptomatic or have only mild symptoms, while others get extremely sick and can die. Now is our opportunity to collect information that can help us target our prevention efforts, provide care that reduces morbidity and mortality, and avoid the most severe economic consequences.
Long-term Effects on Individual and Population Health
Researchers and clinicians are still identifying new consequences of infection with SARS-CoV-2, the virus that causes COVID-19. We already know that the virus can attack many of the body’s organ systems. Many of the immediate results of these attacks have been well-documented, including lesions in the lungs, pneumonia, strokes, liver injury, and immune system overresponse. Since the virus has been in circulation less than a year, the medium- and long-term effects of the infection on organ function remain unclear. The risk of long-term health effects may be significant.
Organ damage incurred during the initial infection could result in long-term sequelae such as diminished lung or heart function. This was the case with the 2003 SARS outbreak, which was also caused by a coronavirus virus (SARS-CoV-1). Twelve months after their initial infection, 28 percent of patients had abnormal chest radiographs, and 24 percent had impaired lung diffusing capacity, exercise capability, and overall health. SARS-CoV-2 infection can cause lung lesions similar to that caused by the SARS-CoV-1 virus, suggesting it may cause similar loss of lung capacity.
We also know that the SARS-CoV-2 virus can remain in the body, reactivating weeks after symptoms resolve and tests for the virus are negative. Coronaviruses in animals can cause chronic infections, with periods of latency followed by symptomatic reactivation with viral replication. In felines, the latent virus resides in the gastrointestinal tract and viral shedding occurs even without symptoms. The evidence for short-term latency with reactivation in humans in conjunction with known long-term latency in animals raise concerns that some patients may develop chronic SARS-CoV2 infections, which would complicate outbreak control efforts.
Although a lower risk, SARS-CoV-2 infection could trigger a pathogenic immune or neurologic response. Such a response has been hypothesized as the cause of post-polio syndrome, a constellation of muscle and neurological symptoms that develops 15 years or more after recovery from paralytic poliomyelitis. The widespread assault of SARS-CoV-2 on the body may increase the risk of such a reaction. Monitoring recovered patients will be critical for early identification and treatment of a post-recovery syndrome.
Following asymptomatic and recovered patients over the long term will tell us what proportion of recovered patients have respiratory or cardiovascular morbidity and will inform our understanding of their long-term health care needs. It will allow us to determine what proportion of recovered patients are permanently disabled and the resulting impacts on Social Security, Medicare, and Medicaid.
Solution: A Longitudinal Registry of COVID-Positive Patients
A public health registry identifies and follows people with a specific exposure or disease over time to determine the long-term impact of the exposure or disease. A registry is a database “containing uniform information about individual persons, collected in a systematic and comprehensive way, in order to serve a predetermined purpose.” A registry of recovered COVID-19 patients with longitudinal follow-up could answer many critical questions about the viral infection. The registry could also serve as a sampling resource for epidemiologic studies to answer specific questions that cannot be answered by the registry alone.
Many registries have already been started by recruiting recovered patients or adding data collection on COVID-19 to existing registries and studies. These registries focus on specific exposed or patient populations, such as health care workers, individuals whose pre-existing disease or exposure puts them at high risk, and pregnant women.
Efforts are underway to coordinate registries and data collection efforts. These efforts include the National COVID Cohort Collaborative, the Office of Behavioral and Social Sciences Research compendium of data collection instruments, and the Centers for Disease Control COVID-19 Community Survey Question Bank. Registries with different data elements or conflicting data formats may still make combining data synthesizing findings across registries difficult, however.
We recommend the formation of a broad registry of individuals who are or have been infected with SARS-CoV-2. To understand the broad range of disease transmission and sequelae, the eligibility criteria for the registry should also be broad including seropositivity—a positive laboratory test, clinically diagnosed, identified as a source of infection through contract tracing. The registry could directly answer research questions on epidemiologic parameters, immune response, infectivity, and reactivation or reinfection. It could serve as an efficient sampling frame for other studies of SARS-CoV-2, including infection reservoirs, public health interventions for slowing transmission, and safety measures for individuals, health care and public health systems, and for businesses. The research value of the registry could be enhanced by maintaining relationships with other registries and a list of COVID-19 registries and their characteristics.
Better understanding of SARS-CoV-2 infection is critical to ameliorate the health, social, and economic impact of current and future outbreaks. Now is the time to collect the data needed for future planning.