The coronavirus outbreak remains a highly dynamic situation, and investors need to approach it with extreme caution, CNBC's Jim Cramer said Friday.
"You need to be prepared and remember my wild card thesis," the "Mad Money" host said. "We don't know what's going to happen with this virus."
While it's clear there may be immediate short-term impacts on the Chinese economy, the bigger picture remains highly opaque, Cramer said.
Yes, all three major indexes closed in the red Friday, with the Dow Jones Industrial Average dropping more than 2% for its worst day since August, but Cramer said it's unclear whether the market has reached a bottom.
The market will need to be "much more oversold" before that determination can be made, he said, and more information needs to be had regarding the coronavirus' incubation period, how it is transmitted and how to combat it.
"It is a deck of wild cards. Why don't we get some real cards on the table, and then we can make better decisions," Cramer said.
Cramer said the market movements on Thursday and Friday illustrate just how uncertain Wall Street is about the coronavirus, which has spread to roughly 10,000 people across the globe.
After the World Health Organization deemed the outbreak a global health emergency Thursday afternoon, the market picked up steam into the close. But then it sold off heavily Friday.
"There are lots of very smart people in this business, but very few of them are infectious disease experts," Cramer said, arguing that Thursday's run shouldn't have happened.
While other uncertainties exist, including the results of Monday's Iowa caucuses, the biggest wild card is the coronavirus, Cramer said.
But there are some steps investors can take right now, Cramer said, primarily looking at stocks that could perform well even if the coronavirus triggers a worldwide economic slowdown.
Even so, Cramer said investors cannot trust the coronavirus "until the disease is cured or the worst case is baked into the averages," he said. "And I don't think we have either right now, even after today's drubbing."