Coronavirus and Immunity
After someone has had COVID-19, are they immune, and if so, for how long? That’s a huge question that will determine how soon we can reopen the world. Now a new research study hopefully answers this question.
Understanding Your Immune System
Your immune system is an amazing nanomachine. Given that our bodies are walking Petri dishes for foreign bacteria and viruses, without an immune system you would be dead in days to weeks. Let’s dig in.
The immune system has an innate part, which is the natural immunity that you’re born with, and an adaptive part, which is how it responds to what you get exposed to on a day to day basis. That last adaptive part has two main systems: humoral immunity directed by B cells and cellular immunity managed by T cells.
B-cells are the antibody makers. Their job is to detect foreign proteins on the surface of cells and make nanomachines called antibodies that will mark those foreign cells for destruction. Antibodies are proteins that are made in a lock and key format. A different antibody is generated for each foreign protein (antigen). IgM antibodies happen early in the disease-fighting process and long-term immunity happens through IgG antibodies.
T-cells are part of what’s called “cellular immunity”. This system doesn’t work through antibodies, but instead through various types of T-cells that recognize foreign antigens and then directly destroy them (killer T-cells).
The New Research
This bicoastal paper out of San Diego and New York was just officially published on Jan 6th (1). The authors analyzed the various parts of the immune memory system response to the SARS-CoV-2 virus in 254 samples from 188 COVID-19 cases. 43 samples were at ≥ 6 months post-infection. This study is pretty unique in that it measured circulating antibodies, memory B cells, CD8+ T cells, and CD4+ T cells, all specific for SARS-CoV-2. In addition, the study subjects ran the gamut from mild to severe hospitalized COVID-19 and followed for up to 8 months.
The bottom line for this one is that 95% of the patients had 3 of the 5 measured parts of the immune system functioning against the coronavirus at 5-8 months post-infection. In addition, parts of the immune system that have conferred very long-term immunity of decades or more in other viruses (B cell memory) didn’t decline over the 8 months of the study and were detected in almost all subjects.
Why This Is a Big Deal
First, this is what we would have expected for immunity after a novel virus. However, the media has done a good job making us all believe that immunity to this virus could be different and that all of us would catch it over and over again ad infinitum in an apocalyptic scenario. Hence, the best paper to date on the topic (this one) clearly shows that immunity is what we should all expect after being infected with the coronavirus.
The upshot? The good news is that for those who have had COVID-19, long-term immunity lasting at least 5-8 months (and likely much longer) should be expected. While more research is still needed, this new paper is a welcome surprise that tilts in the direction of the world reopening.
(1) Dan JM, Mateus J, Kato Y, Hastie KM, Yu ED, Faliti CE, Grifoni A, Ramirez SI, Haupt S, Frazier A, Nakao C, Rayaprolu V, Rawlings SA, Peters B, Krammer F, Simon V, Saphire EO, Smith DM, Weiskopf D, Sette A, Crotty S. Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection. Science. 2021 Jan 6:eabf4063. doi: 10.1126/science.abf4063. Epub ahead of print. PMID: 33408181.