Can an employer require that employees attending a company holiday party be vaccinated?

In the Littler 2 the point video series, Littler attorneys provide general information about a wide range of labor and employment issues, in 2 minutes or less.

Can an employer require that employees attending a company holiday party be vaccinated?
Has the ADA accommodation process changed in light of COVID-19 related issues?
Dear Littler: May We Ask Our Employees About Their COVID-19 Vaccination Status?
What do employers need to consider when engaging with an employee who requests an accommodation to work because of a COVID diagnosis?
What workplace issues should employers consider regarding COVID-19 vaccinations?
What should I do if an employee refuses to wear a face mask?
Dear Littler: How Do We Manage Time Off, Scheduling & Accommodation Requests from Employees with Children Whose Education is Affected by COVID-19?
Is employment and labor litigation proceeding in the COVID-19 business environment?
If an employer fails to provide required notice under the WARN Act, is the employer liable for paying the employees' medical expenses?
What effect will COVID-19 have on worker activism and labor relations?
Do we need to accommodate employee requests for job modifications due to COVID-19?
What are some key considerations for lawfully implementing an on-site temperature screening program for my business?
Can an employer disclose COVID-19 related health information to other employees, customers or vendors?
Many of our employees are dealing with school closures and changes to childcare due to COVID-19 concerns. Will employers need to provide any leave or benefits to impacted employees?
In light of the COVID-19 pandemic, what health-related information can employers ask employees to provide?
What paperwork do I need to support my employees' requests for paid leave so that I can get the refundable tax credit under the new federal laws?
My employees have been ordered to “shelter in place.” Does this mean they are eligible for federal emergency paid sick leave?
What should an employer do if an employee was exposed or potentially exposed to COVID-19?
How does the new Families First law affect COVID-19 related leave?
Given the current health crisis, can an employer require employees to have their temperature taken at work?
What do employers need to consider in allowing or requiring remote work during the COVID-19 crisis?