As Omicron induces a sense of deja vu at the close of the year, we look back at a few key ways in which our understanding has moved forward.

Shawna Williams Dec 16, 2021

https://www.the-scientist.com/news-opinion/what-we-learned-about-covid-19-in-2021-69532

Many iterations

In a year that began with the Alpha and Beta variants (then known as B.1.1.7 and B.1.351, or the “UK variant” and “South African variant”) dominating headlines, and ends with skyrocketing Omicron case numbers in multiple countries, researchers have learned much about the mutations the variants are accumulating, as well as the changes they wreak in the virus’s epidemiology. Some variants, such as Alpha and later Delta, became dominant, while others, including Mu, looked worrying but never spread widely. For those tracking SARS-CoV-2’s evolution, Omicron threw a curveball, its dozens of mutations indicating it split off from other known variants around the middle of last year. How it managed to evolve so long without detection—for example, in an immunocompromised person with a long-term infection, or in an animal population that caught the virus from people—remains a matter of speculation.  

Vaccines helped, but weren’t a knockout punch

The picture looked rosy for vaccines at the beginning of the year, with reported efficacy rates above 90 percent for Pfizer/BioNTech’s and Moderna’s mRNA jabs, and multiple other versions rolling out around the world. Indeed, while breakthrough infections did occur, COVID-19 hospitalizations tanked among the vaccinated. But many unknowns remained, such as what the vaccines’ effectiveness would be against current and future variants, and whether protection would wane over time, requiring booster shots. While vaccine effectiveness against symptomatic disease turned out to dip only modestly against Delta, preliminary data indicate the story could be bleaker for Omicron—although protection against severe disease appears to remain high.  

As for boosters, the US Food and Drug Administration (FDA) has now authorized them for everyone 16 years or older—a controversial move given that many countries still have a dearth of vaccines, leaving the door open not only to preventable suffering and death, but also to the rise of further variants. 

What treatments might work (and which likely don’t)

The year brought bad news for the use of plasma from people who recovered from COVID-19 to treat those with the disease. The FDA had authorized the use of convalescent plasma for COVID-19 in summer 2020 despite uncertainty around its benefits, and earlier this year, as further studies showed a lack of benefit for most patients, the agency narrowed its emergency use authorization. This month, based on the results of multiple clinical trials, the World Health Organization recommended against use of convalescent plasma for COVID-19. 

More notoriously, many people attempted to treat themselves this year with the antiparasitic medication ivermectin, as controversy over the drug—particularly around the quality of studies that have purported to show its benefits in COVID-19 patients—continued. 

Later in the year, some bright spots emerged in news about new potential treatments—specifically, antiviral pills. In October, Merck announced that its experimental drug lowered the risk of hospitalization with COVID-19 by 50 percent, although it later downgraded that number to about 30 percent. Pfizer’s Paxlovid also emerged as a promising contender, with a recently reported 89 percent efficacy at preventing hospitalization and death. 

A new top dog

One of the most striking insights into SARS-CoV-2 in The Scientist’s coverage this year came, of all places, from a story on how mountain lion behavior changed during a lockdown in California. “We’re generally used to thinking of humans as the top dog in ecosystems, and the kinds of impacts humans have influence other species and then might ripple beyond to influence the species those species influence,” wildlife ecologist Chris Wilmers told editor Jef Akst. “Now instead of humans being on top, we’ve got the virus that’s on top, changing human behavior, which then influences mountain lions and has the potential to continue to cascade through the food web.”