Re-Infection Related Questions
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Frequently Asked Inpatient Questions Microchapter |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Nuha Al-Howthi, MD[2]
Re-Infection Related Questions
Do patients become immune after recovering from COVID-19?
- Currently, there is no evidence to suggest that individuals who have recovered from COVID-19 and have antibodies present in their blood are immune or protected from reinfection.[1]
Is re-infection worse than the initial infection?
Will a re-infected person show the same symptoms as the initial infection?
Are clinically recovered persons infectious to others if they test persistently or recurrently positive for SARS-COV-2 RNA?
Whether the presence of detectable but low concentrations of viral RNA after clinical recovery represents the presence of potentially infectious virus is unknown. Based on experience with other viruses, it is unlikely that such persons pose an infectious risk to others. However, whether this is true for SARS-CoV-2 infection has not been definitively established. Typically, after the onset of illness, the detectable viral burden declines. After a week or more, anti-SARS-CoV-2 immunoglobulin becomes detectable and antibody titers rise. Some of these antibodies may prevent the virus from infecting cells in cell culture. The decline in viral burden is associated with decreased ability to isolate live virus. Efforts to isolate live virus from upper respiratory tract specimens have been unsuccessful when specimens are collected more than 10 days after illness onset. Persons who have tested persistently or recurrently positive for SARS-CoV-2 RNA have shown stable or improving signs of illness. When viral isolation in tissue culture has been attempted in such persons in South Korea and the United States, live virus has not been isolated. In addition, there is no evidence that clinically recovered persons with persistent or recurrent detection of viral RNA have transmitted COVID-19 to others. Despite encouraging observations to date, it’s not possible to conclude that persons with persistent or recurrent detection of SARS-CoV-2 RNA are no longer infectious. There is no firm evidence yet that the antibodies that develop in response to infection are protective. If these antibodies are protective, it’s not known what antibody titers are associated with protection from reinfection. Based on these data and experience with other viral infections, most persons recovered from COVID-19 who test persistently or recurrently positive by RT-PCR are likely no longer infectious. Additionally, the magnitude and persistence of the immune response following recovery may vary among individuals, with factors such as age potentially influencing protection. Based on limited available data, determinations must be made on a case-by-case basis as to whether recovered persons with persistently detectable SARS-CoV-2 RNA are potentially infectious to others and should continue to be in home isolation and excluded from work, school, or other group settings. Such determinations are typically made in consultation with infectious diseases specialists and public health officials, after review of available information (e.g., medical history, time from initial positive test, RT-PCR Ct values, and presence of COVID-19 signs or symptoms).
What further evidence is needed to be reassured that persistent or recurrent shedding of SARS-COV-2 RNA after recovery does not represent the presence of infectious virus?
Prospectively collecting serial respiratory samples and attempting to isolate live virus in tissue culture from multiple persons testing positive by RT-PCR following illness recovery is generally required. If repeated attempts to recover replication-competent virus in culture from such serial samples are unsuccessful that is considered sufficient evidence that infectious virus is absent, and that persons continuing to test positive do not pose an infectious risk to other people.
What do we know the detection of SARS-COV-2 RNA after clinical recovery of covid-19?=
Many recovered persons do not have detectable SARS-CoV-2 RNA in upper respiratory tract specimens. In others, viral RNA can be persistently detected by RT-PCR in respiratory tract samples after clinical recovery. In some persons, after testing negative by RT-PCR in two consecutive samples, later samples can test positive again. Whether persistent or recurrent, these repeated detections of viral RNA consistently are associated with higher cycle threshold (Ct) values (i.e., fewer RNA copies) than were found in earlier RT-PCR results in samples collected shortly or and during clinical illness. Studies that have looked at how long SARS-CoV-2 RNA can be detected in adults have demonstrated that in some persons it can detected for weeks.