Some of the companies have not announced their plans publicly, despite having made a decision not to attend. But HIMSS said it hasn't instructed any exhibitors to withhold information from their partners and customers.
The companies cited fears that the coronavirus will spiral into a global pandemic.
For tech companies, pulling out means missed opportunities to pitch their technologies and tools to the $3.5 trillion medical sector. Companies will spend massive marketing budgets on building out their presence at the conference to win over deals over their competitors, and spend months prepping their sales teams.
HIMSS, which is scheduled to begin on March 9, made the decision not to cancel the conference altogether, even as other big conferences are shuttering. The Game Developers Conference , CERAWeek and the in-person portion of Facebook's F8 are among the conferences that have been cancelled in the interests of public health and safety.
HIMSS said it would continue to update attendees on the "attendance and status," and that it is conferring with a medical advisory board.
"As of today, as we are still planning to hold the conference as scheduled, we do have an external advisory panel to further advise us so that we can make sure we're making the best evidence-based decisions," a spokesperson for HIMSS said.
President Trump announced plans on Monday to attend the conference to push companies in attendance for the interoperability of medical information.
Cisco was the first company to pull out of the conference, and it issued a public statement over the weekend. Intel followed suit, confirming to CNBC that the safety and well being of its employees is the "top priority."
"As a precaution, we have implemented travel restrictions to areas significantly impacted by the ongoing coronavirus outbreak, and restricted attendance at events that don't apply similar travel restrictions to attendees. We're monitoring the situation closely and working to ensure that our employees have the information and resources they need to stay safe," an Intel spokesperson told CNBC.
Salesforce and Tableau also made the decision to pull out on Monday. Amazon AWS notified its customers and partners before confirming that it would withdraw on Tuesday.
Amazon AWS, which was slated to have a big presence at HIMSS this year, said in a statement: "We've reached this decision after much consideration, as the health and safety of our employees, customers, and partners are our top priority."
As of Tuesday morning, Google Cloud and Microsoft are still planning to exhibit at HIMSS, but many of the employees based outside of the U.S. won't be able to attend due to their companies' restrictions on international travel. Both companies will likely have a reduced presence.
CNBC's Jordan Novet contributed to this report.