A small glimmer of light in the darkness:
https://www.sciencemag.org/news/202...vid-19-patients-bode-well-long-term-immunity#
One of the things mentioned in the article is potential cross-immunity from prior infection with one of the common hCoVs (human-Coronaviruses).
Back in early-mid February, it was one of the possible explanations I'd wondered about, as to why young children in Wuhan/Hubei seemed largely unaffected by this (as there hadn't really been widespread infection outside China at the time).
hCoV-OC43 (also a beta-Coronavirus like SARS-CoV-2) has hit Wuhan every season for the past few years, especially circulating amongst younger children. Although the antibodies produced from infection with one of the common hCoVs typically only last 1-2 years, regular/repeated exposure seems to maintain a level of antibodies, and maintained immunity.
Eg. After getting sick due to OC43 the first time, with yearly exposure, the same child is still fairly immune/resistant to it 3-4 years later, or experiences a much milder cold vs a child who got sick from it 3-4 years ago and has had no exposure to it in the interim period, and gets it again 3-4 years later when the immunity/resistance is gone.
I'd wondered about the feasibility of intentional infection with OC43 to provide some cross-immunity for SARS-CoV-2. Even if it doesn't completely prevent infection, but can lessen the severity, it's potentially worth pursuing.