Supermarkets across the country are reporting long lines as Americans rush to stock up on everything from toilet paper to frozen food to medicine following the World Health Organization ruling coronavirus a pandemic on Wednesday and closures of everything from professional sports leagues to some K-12 school systems.

But some shoppers were already stocking up before this rush. A total of 34% of Americans were purchasing slightly more (18%) or significantly more (16%) last week as a result of coronavirus fears, according to a survey conducted by Civis Analytics, a Chicago-based data science software firm. The survey was conducted among 1,951 Americans between March 4 to 6 and shared exclusively with Fortune.

And last week many Americans were already finding some common household supplies out-of-stock. The products that shoppers reported being out-of-stock include hand sanitizer (20%), bottled water (15%), mask/filtering respirator (13%), and antiseptic wipes (12%).

While industries like airlines and cruise lines are already seeing negative impacts from the virus, supermarket chains could actually see a short-term boost. Last week, Costco attributed a February sales boost to Coronavirus-concerned shoppers. 

The survey was weighted to match the U.S. adult population on age, education, ethnicity, gender, and race. Civis plans to repeat the survey weekly, with the next poll being released next week.

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