The Centers for Disease Control and Prevention finally released guidance last week allowing vaccinated people to remove masks while outside, nearly five months after vaccines started to become available nationwide. This comes weeks after the CDC said vaccinated Americans can board an airplane. But noticeably absent from these piecemeal recommendations is any guidance on the big question facing businesses: When and how should they bring employees back to the office? It's a question with big implications for the livelihoods of many Americans and the economy.

In the absence of CDC leadership, companies are scrambling to figure it out on their own. It's the Wild West. Salesforce announced in mid-April a phased plan in which fully vaccinated employees can voluntarily return to the office subject to safety protocols, including twice weekly on-site coronavirus testing. JP Morgan also recently announced it will open its U.S. offices to all employees in May and apply a 50 percent occupancy cap. But why is every business being forced to invent the wheel on their own?

Large companies are hiring high-paid medical consultants, but companies without the resources to seek such advice are stuck trying to sense the direction of the wind. The hardest blows are to small businesses, especially minority- or woman-owned companies. These are also the businesses at greatest risk of bankruptcy if they get the timing wrong.

Public health officials should not only quickly address this need, but also tailor their guidance to the type of employee. A utility worker or groundskeeper should not have to wear a mask when working alone outside on a hot summer day even if they chose not to get vaccinated. Having such a mask requirement is incompatible with science, ethically wrong and potentially harmful to the worker. Conversely, a nonimmune office worker should wear a mask indoors until the local infection rate drops below a preset threshold. The country is looking to the CDC for guidance; its delay in providing it is slowing down America's economic engine.

Without medical answers, business leaders will be forced to use public opinion as their compass. But this approach makes businesses dependent on a distorted perception of infection risk that fluctuates based on media headlines about new strains of the virus and political rhetoric rather than best medical practices. In fact, business plans to bring back workers thus far sometimes resort to over-testing for those already immune, which is not grounded in data or clinical wisdom.

The lack of CDC guidance also transfers legal risk to businesses. Clear guidance would consider criteria such as the percent of residents vaccinated and local rates of infection and establish clear thresholds. It would also answer questions that employers ask us time and again: Should they return to in-person working in phases? Should phasing depend on immune status? How should daily symptom checks, temperature checks, contact tracing and measures change for employees who are immune?

The problem is not a lack of scientific evidence; it's a problem of timeliness. More than a month ago, a paper in NEJM Catalyst demonstrated the benefits of covid-19 back-to-work programs. Partnering with a large manufacturing company, the authors demonstrated how a large multistate company can create a safe work environment with high employee engagement and a nearly 3-to-1 return on investment. Guidance such as this needs to be coming from the top.

Part of the challenge has been structural. The covid-19 task force that President Biden launched during the transition did not include any business leaders. The announcement by the administration of a new partnership with business leaders was a step in the right direction, but it has yet been unclear what its mandate is and whether and what new guidance will come from it.

America's businesses have long demonstrated remarkable ingenuity. But figuring out when and how to safely open their offices shouldn't be entirely on them. What they need is clear leadership from the CDC. Americans are ready to get back into the office. Let's help them do it safely and without unnecessary delays.

Shantanu Nundy is chief medical officer of Accolade and author of "Care After Covid: What the Pandemic Revealed is Broken in Healthcare and How to Reinvent It." Marty Makary, a professor at the Johns Hopkins School of Medicine, Bloomberg School of Public Health and Carey Business School, is chief medical adviser to Sesame Care and author of "The Price We Pay."