Q: Is it safe to allow them to spend a few days at our house over Thanksgiving? Can they still spread the virus?
A: So long as your son (and friends) have been fever-free for 24 hours, it’s been at least 10 days since he was diagnosed, and his symptoms are getting better then you can treat them like you would any other college student returning from school.
These are the most current guidelines for leaving isolation after being diagnosed with COVID-19. He does *not* have an immunity passport, and still needs to take “SMART” precautions against the virus.
The 10 day guideline is based on extensive contract tracing studies done in China and within the United states. Contacts that were exposed 10 days after the onset of symptoms did not get COVID-19. Contacts exposed in the first 6 days following the first symptoms were more likely to get COVID-19. More information can be found at the CDC link below.
Although he might still test positive for several weeks after infection, researchers have found that in mild to moderate cases of COVID19 after 10 days from the time the symptoms start, the virus was not “replication competent”, that means being able to infect a cell and produce additional copies of itself. Because the virus was not “replication competent” it is mostly a dead virus that is not able to grow and spread. Because these replication INcompetent viruses hang around for quite a while following infection, re-testing by nasal swab is not recommended in the majority of cases.
Severe COVID-19 cases (such as those that require intensive care treatment) can have replication-competent viruses for longer than mild and moderate cases. But, even in people with severe COVID-19, 88% no longer contained replication competent viruses after 10 days, and 95% didn’t after 15 days. This is why people with severe disease are told to isolate for longer–20 days of isolation is recommended as well as consultation with infectious disease health care providers.
After infection with COVID-19, people develop an immune response against the virus such as antibodies that can remain for several months. However, the levels of antibodies and immune response wane over time and can be different levels in each person. How much protection each person develops and for how long is not yet clear at this time. Your son and his friends should NOT consider themselves as having an “immunity passport.” They should still use precautions like masks and physical distancing to avoid re-exposure to SARS-CoV-2 and the possibility of transmitting it to others.
So, as long as your child had a mild-moderate case of COVID-19, is 10 days out from his first symptoms and getting better, then you can treat him and his friends as you would any other college-age children returning for the holidays. We encourage you to read the Dear Pandemic considerations for college-age children returning home for Thanksgiving in the links below.
CDC guidance on duration of isolation and precautions for adults with COVID-19
Dear Pandemic considerations for college age children returning home for Thanksgiving
Dear Pandemic information on re-infection