Editors’ Note: This article was accepted on Jan. 21, 2020, and was accurate at that time. Because information about SARS-CoV-2 and COVID-19 is evolving rapidly, please verify these recommendations and information.

With thousands of articles published weekly on COVID-19, navigating the literature on this emerging infectious disease can be daunting. To help health care professionals and the general public keep up and to fight medical misinformation, a group of emergency physicians started the website Brief19.com, which publishes analysis of COVID-19 research and policy five days a week, all for free. Here are highlights from recent Briefs.

When word surfaced that a novel coronavirus was responsible for the outbreak of a deadly new severe acute respiratory syndrome in December 2019 in China, few people, if anyone, knew what to make of it. A year later, we know that COVID-19 will go down as the first truly historic pandemic of the 21st century. But before that was obvious, physicians and public health experts looked for ways to contextualize what was happening. Everyone, here and around the world, wanted to know how worried to be. The natural inclination in trying to understand a devil we did not know, SARS-CoV-2, was to try to compare it to one that we did, seasonal influenza. 

As I wrote with Carlos del Rio, MD, professor of medicine at Emory University School of Medicine in Atlanta and infectious diseases specialist, last year in JAMA Internal Medicine, that was a major cognitive blunder.¹ The main problem, we wrote, was the statistic that we all repeat by rote—that around 40,000 to 60,000 people die of influenza in the United States annually—was and has always been a clunky estimate. That figure includes a series of corrections that just don’t hold up. 

COVID-19 At A Glance
7-day Percent Change in COVID-like illness

ACEP

For example, the model used by the U.S. Centers for Disease Control and Prevention (CDC) assumes that scores of hospitalized patients die of influenza but never get tested for flu. That assumption struck us as odd since I can’t admit a patient with appendicitis in January without sending a flu swab, let alone anyone with respiratory symptoms. Indeed, it’s likely that low-acuity cases of influenza are substantially underreported in the community. But the notion that the health care system is somehow missing a majority of influenza deaths just does not have face validity. If anything, it’s likely that the infection fatality rate for seasonal influenza is far lower than the 0.1 percent rate the CDC and the World Health Organization routinely cite; we probably know about the vast majority of flu-related deaths, but we probably detect relatively few of the milder cases. In our analysis, we estimated that COVID-19 in the spring was already killing between 9 and 44 times more people than flu does at its peak. It’s possible that it’s even worse than that, but in reality, it depends how you measure.

This fall, many people started to worry about the possibility of “twinfluenza,” or the idea that come winter, we’d be fighting COVID-19 and seasonal flu all at once.² The good news is that seasonal influenza appears to have been substantially reduced—in some areas, there has scarcely been any flu at all. This may be due to two major changes. First, our friends in the southern hemisphere, specifically in Australia and New Zealand, all but eliminated flu during their flu season (June–Aug.). That means fewer mutations and less circulating virus (and less travel means less overseas transmission). Second, the interventions that flatten the COVID-19 curve, like physical distancing and mask wearing, might be decimating flu. 

The CDC has been tracking reports of influenza-like illnesses (ILIs) for years. Now, it also tracks coronavirus-like illnesses (CLIs). A new tool on ACEP’s website (pictured above) allows users to track and compare them, including by region and date.³ What’s clear is that, at the moment, ILIs don’t hold a candle compared to CLIs. ILIs are way down from previous years. Will this change last? Will we in the United States start wearing masks during ILI and CLI season, as many people in some nations in Asia do? If so, we may have learned something beneficial from this horrible crisis that will save lives (and misery) for decades to come.