The earliest reports of a novel virus causing an unusual pneumonia emerged in December 2019. In the weeks that followed, the global scientific community identified the virus — a coronavirus, like the viruses that caused SARS and MERS — and named the disease it causes: COVID-19. It spread quickly around the world, upending the rhythms of day-to-day life, changing the patterns of human behavior, stressing health care systems, and killing millions.

An unprecedented effort to quickly develop vaccines paid off in late 2020, when pharmaceutical companies like Pfizer and Moderna released data showing that their shots were highly effective. A vaccination campaign quickly helped protect people in higher-income countries like the United States and the United Kingdom, preventing hundreds of thousands of deaths. But vaccinations lagged in lower-income countries, and vaccine equity continues to be a major issue.

New highly contagious and immune-evading variants, like delta and omicron, drove resurgences of the virus around the world through 2021 and 2022. Broad exposure to the virus and vaccine coverage helped limit the damage.

Experts say that the coronavirus isn’t going to go away. Population-level immunity and broader access to vaccines will defang its threat, and COVID-19 won’t always be an active public health emergency. But it’s another addition to the list of respiratory viruses we contend with each year.

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