Vaccines, on the other hand, are believed to induce more potent and longer-lasting immunity. They’re also a lot safer than waiting to catch the virus for the first time – or waiting to see it again, as we don’t know how common reinfections are.
While most presume that the second time around, you’d get a more leisurely ride, one 25-year-old man from Nevada was infected with two variants of the virus within a 48-day timeframe. When he caught COVID-19 the second time, his symptoms were more severe, and he ended up in hospital needing oxygen support.
“Our assumption has always been that natural immunity to the coronaviruses is rather fragile and short-lived,” says Daniel Altmann, a Department of Immunology and Inflammation professor at Imperial College London.
This is because the family of viruses has several tricks to “subvert normal immunity,” he explains. “The vaccines can overcome this and induce much stronger, more lasting immunity as they work differently. They present a single protein – spike – to the immune system on a stimulatory platform.”
How Your Body Fights Off COVID-19
This is the default response to any virus entering the body. As part of this initial response, inflammatory proteins called interferons are released, which have antiviral functions. The aim is to stop the virus in its tracks – though we don’t actually know how well this first response works in fending off infection.
While the innate immune system is trying (and sometimes failing) to fight off the virus, it also talks to the more specific adaptive immune response. This is your body’s tailor-made solution for dealing with COVID-19, and involves the release of B-cells, which produce antibodies, as well as T-cells, which kill infected cells.
If your body comes into contact with the virus again, it’s thought these B-cells and T-cells can be activated a lot quicker than they were last time to deal with the intruder.
The dosing matters too – at the moment, we need two doses of the vaccine for the best protection. Bryn Boslett, an infectious disease expert leading the vaccination effort at the University of California San Francisco, suggests the body’s response to COVID-19 infection would be similar whether you’d had the first dose of the vaccine or had previously been infected with the virus. But when you get the second dose of the vaccine, you’re further training your immune system, she said in a Q&A on the topic. “You’re strengthening that response from the antibody-producing B cells, and you’re also activating T memory cells that stick around for much longer.”