In what appears to be a broader trend in online advertising due to the COVID-19 outbreak, RBC Capital Markets analysts lowered estimates for several online companies based on lower guidance and an absence of advertising across Google Search.

Analysts conducted some analysis after hearing public disclosures from major companies and found zero paid-search ads across more than 35 Google searches in the travel and restaurant categories.

“We can’t recall ever NOT seeing a Paid Ad under the search term “Las Vegas Hotels”… Anecdotal?” RBC Capital Analyst Mark Mahaney wrote in a note published late Thursday. “Yes. But we think this is indicative of the broader trends across Online Advertising.”

While the title of the research note — Taking Down Ad Numbers … Again — pretty much explains it all, analysts expect the industry to experience the “trough” during the second quarter. It was the third time in three weeks that the analyst firm revised numbers based on guidance from the companies, according to the reports.

Twitter said it would likely see a year-on-year decline when it reports first-quarter revenue of between 15% and 25% YoY decline in ad revenue in the month of March, despite user growth.

Analysts also point to Facebook’s disclosure that it is seeing weak revenue from its ad business in countries taking aggressive steps to reduce the spread of COVID-19.

Booking Holdings, which owns brands like Kayak and OpenTable, reported that companies are “dramatically reducing spend” worldwide. RBC estimates Booking Holdings companies account for 3% of Google’s worldwide ad revenue.

“The CEOs of UBER and RDFN have publicly disclosed materially pulling back on marketing spend, and our discussions with a series of other Internet companies  — ranging from EXPE to CARG to LYFT to ZG — all leave us with the impression that Net marketing budgets are being reduced, curtailed or even outright pulled,” he wrote.

Google and Facebook will see the least impact, Mahaney wrote, because they have the most proven return on investment, although Google’s “massive size and travel vertical exposure is a clear headwind.” Twitter will see the most impact. Any sizeable amount of marketing spend on Snapchat and Pinterest falls under “test budgets,” he wrote.