Recently, Moderna announced a significant milestone in their quest for a COVID-19 vaccine (more on the particulars of this below). In response, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said he expected 100 million COVID-19 vaccine doses by early 2021. This would be completely transformative. But developing and manufacturing new vaccines typically takes years—decades in many cases. There’s reason to hope that a COVID-19 vaccine could come sooner, but as hopeful as anyone, including Fauci, may be, there are still many unknowns.
No one has a crystal ball. But we can help you understand what’s happening in COVID-19 vaccine research, what we do know, and why there’s so much that we don’t.
Even the most innovative COVID-19 vaccine candidates would work on the same basic principles as all vaccinations. To understand that, here’s a brief review of some immunology fundamentals. (For more, see this Path of the Virus explainer.)
When your immune system meets a viral threat, it begins fighting with a generic response, which is not specific to any particular virus. But during the first one to two weeks after infection, your adaptive immune cells kick in. These cells learn to recognize specific structures of the virus, called antigens, and train to target the virus once they recognize it. Adaptive immune cells do many things, but one of the major ways they protect you is by producing antibodies. You’ve probably heard quite a lot about antibodies lately. They’re large proteins created to target and stick to the antigens on the virus, and kill it.
Importantly, some adaptive immune cells become “memory cells,” long-lived cells that remain in your body, ready to quickly ramp up a fight against re-infections of the same pathogen so that your body doesn’t have to start from scratch next time. These memory cells, along with antibodies which also stick around in your body, are key to viral immunity.