A requirement for federal workers and contractors to be fully vaccinated for COVID-19 — which would affect a number of transportation companies that work with the U.S. government — won’t exacerbate a backlog of shipping and deliveries, according to the Biden administration.

“The requirements for federal workers and contractors will not cause disruption,” Jeff Zients, President Joe Biden’s coronavirus response coordinator, said at a Wednesday briefing for reporters. 

Organizations that have instituted vaccine mandates have seen overwhelming compliance, and those who refuse will go through education and counseling before any enforcement, Zients added.

Some industry groups and firms have warned that the vaccine requirement would cause further transportation disruptions and undercut Biden’s ability to smooth out bottlenecks in the supply chain, and called for exemptions or delays. The U.S. continues to grapple with backlogs at ports and delays in shipments, which pose a political threat to Biden.

The vaccination requirement for federal workers takes effect on Nov. 22, while the rule for contractors kicks in on Dec. 8.

“There’s still weeks until we reach those deadlines and it’s important to remember those deadlines are not cliffs,” Zients said. “The purpose I think most importantly is to get people vaccinated and protected, not to punish them.”

The U.S. is also preparing a rule that would require vaccination, or weekly testing, for any company with 100 or more employees. It’s not clear when it will take effect. Zients said the rule would “be finalized soon” and declined to specify what impact that would have on supply chains.