The cleverest of enemies thrive on surprise attacks. Viruses—and coronaviruses in particular—know this well. Remaining hidden in animal hosts for decades, they mutate steadily, sometimes serendipitously morphing into more effective and efficient infectious agents. When a strain with just the right combination of genetic codes that spell trouble for people makes the leap from animal to human, the ambush begins.
Such was the case with SARS-CoV-2, the coronavirus behind COVID-19, and the attack was mostly silent and insidious at first. Many people infected with SARS-CoV-2 remained oblivious as they served as the virus’s new home and allowed it to establish a foothold in the global human population.
