This week the coronavirus all but ground Western civilization to a halt, closing off gathering places that included schools, political rallies and sporting events. On Friday U.S. President Donald Trump, declared an emergency, freeing up $50 billion in aid to states, after repeatedly minimizing the contagion’s potential impact. Despite his exposure to an infected Brazilian visitor, Trump shook hands with officials at his announcement.

What’s being done? Yesterday Congress passed an aid package, which Trump has agreed to sign, that guarantees universal free virus testing, paid leave and $1 billion in food aid.

Keep up with the crisis at OZY’s Coronavirus Central.

After the biggest drop since 1987 on Thursday, U.S. market indexes surged Friday after President Donald Trump’s emergency declaration on the coronavirus. The Dow Jones Industrial Average set a one-day record, climbing 1,985 points, or 9.4 percent. The S&P 500 and Nasdaq indexes both rose 9.3 percent. The emergency frees up $50 billion in assistance to states for fighting the coronavirus, while the Federal Reserve pledged $30 billion in Treasury security purchases to shore up shaky markets.

Is this sustainable? With indexes still 20 points below recent record highs and the economic harm of COVID-19 clarifying, “sustained recovery … is unlikely,” said one investment officer.

OZY explores America’s limited stimulus options.

He seems as inevitable as coronavirus. Going into Tuesday’s big-state primaries in Illinois, Florida, Ohio and Arizona, OZY’s latest Forecast gives former Vice President Joe Biden an 89 percent chance of locking up the nomination in Milwaukee — to Sen. Bernie Sanders’ 2 percent — even if the contagion turns the Democratic National Convention into a giant videoconferencing experiment. Meanwhile, Louisiana party officials, concerned over COVID-19 risks, have postponed their April 4 primary until June 20.

Can they do that? According to the national party’s leadership, no. They’ve set a primary deadline of June 9, but said they’re going to try to accommodate virus contingency plans.

“If the people demand it, let it be so.” With that, Russian President Vladimir Putin assented to lawmaker Valentina Tereshkova’s offer to reset his time as president to zero with a constitutional amendment. But will Russians stand for this, and does Putin even want to remain president, wonders journalist Joshua Yaffa. Tereshkova said Putin’s running again would be a “stabilizing factor,” which is a powerful argument in uncertain times.

How did he pull it off? The proposed amendment elicited speculation that Putin would move to a new role, leaving potential rivals guessing until this week’s bombshell.

The U.S. ban on travelers from 26 European nations has gone into effect. Microsoft co-founder Bill Gates is leaving Microsoft’s board of directors. And New Yorkers are taking to bicycling as a way to avoid exposure to fellow commuters.

In the week ahead: On Sunday, Democratic presidential candidates plan to debate in Washington, D.C., with no live audience after the event was moved from Arizona over coronavirus concerns. Tuesday is St. Patrick’s Day, but many events have been cancelled to curb the virus’ spread. And U.S. Federal Reserve board members are expected to cut interest rates to zero on Wednesday.

Coronavirus Tip: OZY explains the essentials to stock up on for a self-quarantine at home, for health, sustenance and fun.

“Flattening the curve” could save lives, but what exactly does that mean? The Centers for Disease Control and Prevention first released the now famous graph, which features a sharp spike in cases and a second, more gradual uptick. Flattening that curve looks like slowing down the spread of the virus, which, the theory contends, could help keep demand for ventilators and medical professionals from far exceeding the health care sector’s capacity.

How can you help? The most effective way to help flatten it out, experts say, is avoiding gatherings, washing hands frequently and staying home if sick.

Stay informed with OZY’s Coronavirus Central.

Ignore them at our peril. Dealing with homelessness has always been an agonizing struggle, but as the world mobilizes against COVID-19, its realities have become more stark, OZY reports. Social distancing in shelters is nearly impossible and their residents often have underlying health problems, making the illness particularly deadly for them. Major U.S. cities are attempting mitigation, including Seattle’s use of tiny homes to isolate homeless patients.

How could this affect others? Shelter outbreaks could put particular strain on medical resources, as the homeless can’t self-isolate while waiting days for test results.

It lends gravity to “sharing is caring.” Data scientists say the world needs a one-stop database to fully understand the coronavirus. A group of scientists have argued for the establishment of such a tool, saying the Ebola outbreak and other crises made it clear that access to the newest research is paramount. Accurate analytics will help identify the usefulness of prevention strategies, the scientists say, helping slow infections further.

Will we see a repository of data in time? The beginning of a database is in the works, with a focus on mapping the potential future of the virus.

It just feels right. According to Yelp, the use of “crispy” or “crispiness” in U.S. reviews has increased 20 percent in the past decade. Researchers believe that people find crispy foods “appealing” and “enjoyable” and that we associate the sound of crispiness with “fun” and “pleasantness.” Our brains appear to be wired for deep-fried everything.

Why is that? Journalist Alex Beggs explains it has a lot to do with biology, psychology and engineering, while researchers have found that crispiness signals “freshness and safe-to-eatness” going back to our Stone Age forebears.

In the most momentous shift in professional sports in generations, everything from America’s National Basketball Association to the NCAA’s March Madness to English Premiere League soccer were suspended this week over coronavirus concerns. Some credit the NBA’s Rudy Gobert, who like many was dismissive of COVID-19 warnings. The Utah Jazz center even touched reporters’ equipment at a Monday press conference as a joke — before he tested positive Wednesday.

What happened? Now the journalists and Jazz opponents are under self-quarantine and at least one teammate is infected, as was a Rhode Island child who recently got a Gobert autograph in Boston.