The Occupational Safety and Health Administration released updated FAQs on the vaccine-or-test Emergency Temporary Standard and its applicability to commercial truck drivers. 

In the new FAQ, OSHA answers Does the vaccine-or-test Emergency Temporary Standard apply to truck drivers in this way:

There is no specific exemption from the standard’s requirements for truck drivers. However, paragraph (b)(3) provides that, even where the standard applies to a particular employer, its requirements do not apply to employees “who do not report to a workplace where other individuals such as coworkers or customers are present” or employees “who work exclusively outdoors.” Therefore, the requirements of the ETS do not apply to truck drivers who do not occupy vehicles with other individuals as part of their work duties. Additionally, the requirements of the ETS do not apply to truck drivers who encounter other individuals exclusively in outdoor environments. On the other hand, the requirements of the ETS apply to truck drivers who work in teams (e.g., two people in a truck cab) or who must routinely enter buildings where other people are present. However, de minimis use of indoor spaces where other individuals may be present (e.g., using a multi-stall bathroom, entering an administrative office only to drop off paperwork) does not preclude an employee from being covered by these exemptions, as long as time spent indoors is brief, or occurs exclusively in the employee’s home (e.g., a lunch break at home). OSHA will look at cumulative time spent indoors to determine whether that time is de minimis.

Even when the requirements of the ETS do not apply to specific truck drivers pursuant to paragraph (b)(3), those truck drivers are still counted for purposes of the 100-employee threshold for coverage under paragraph (b)(1) of the ETS. 

The ATA and several other state associations are currently involved in a lawsuit that would remove the ETS and expect a final judgement from the Supreme Court soon. You can view this toolkit from the ATA to help prepare for compliance with the ETS.