(Bloomberg) -- In the days around Thanksgiving, Wall Street strategists focus on a couple of things: turkey, football and finessing their year-ahead outlooks. This year, all of that was upended.

News of a new Covid-19 variant hit global markets the day after the U.S. holiday last week, with the S&P 500 suffering one of its worst days of 2021 on Friday. That prompted many traders to scrap their old playbooks and turn to Covid-tracker websites, obscure scientific journals and Anthony Fauci’s television appearances. Mobility reports from Apple and Google are getting bookmarked again, and the TSA flight website is getting refreshed. 

Such data is “something people needed to dust off and say, where are we and what does this look like?,” Art Hogan, chief market strategist at National Securities Corp., said by phone. “Because all of a sudden, this became the headline story of the day and people reverted back and said, you know what, we should probably remember how to do this.”

It’s a throwback to the dark days of 2020, and many strategists are once again looking at and incorporating Covid-19 data trends into their game plans. That includes case counts, positive test rates and hospitalizations, along with how frequently consumers are visiting restaurants or using unemployment sites. Hogan says he’s checking flight and mobility sites as well as trends data from Johns Hopkins University, which offers resources info on the virus. He isn’t making any changes to his outlook yet -- he put out his views the week before Thanksgiving -- but he’s watching developments closely.

At Deutsche Bank, Jim Reid acknowledged clients had been more interested in Covid trends in recent days. He had been publishing such data as part of his daily note but ceased doing so as it improved. Now, it’s something he’s getting calls for again. “We’ve had a number of requests to bring back our Covid tables,” he said last week following news of Austria’s lockdowns. 

Governments across the globe stepped up restrictions as the variant spread and the World Health Organization warned that omicron, as it’s known, could fuel a surge in infections. It’s caused a bout of volatility for markets, with the S&P 500 on Tuesday down 1.3% and safe-haven gold even down 0.4%. The U.S. equity benchmark is now roughly 3% off its record highs reached earlier this month. 

“Not withstanding all these other factors that we typically look at -- earnings, economic data, Fed policy -- we have identified that the greatest swings since the Covid outbreak initially have been triggered by Covid news,” said Greg Bassuk, chief executive of AXS Investments, by phone. “And going forward, we will also say it’s a new normal where global pandemic data absolutely needs to be looked at through as much of a microscope as historically for corporate earnings, economic news and Fed policy.”

Jamie Cox, financial adviser and managing partner at Harris Financial Group, is more interested in observing Covid trends than earlier in the pandemic, as now there is historic information on earlier cycles in the pandemic that can aid predictions about newer variants. 

He looks at First Trust’s Covid-19 Tracker, rife with data about case counts, death rates, and vaccinations, every time the report is published. 

“It’s very, very helpful information,” said Cox.

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