President Joe Biden is expected to announce on Thursday that all federal employees will be required to be vaccinated for COVID-19 or commit to regular testing. In doing so, the third-largest employer in Philadelphia — the federal government — will be joining the largest employer, the University of Pennsylvania, which made a similar announcement in June.

The second-largest employer, the City of Philadelphia, is currently only encouraging employees to get the vaccine but not requiring it. This is a mistake. As the delta variant of the coronavirus spreads, the city should set an example for other employers and for businesses more generally.

» READ MORE: Some cities are requiring government workers to be vaccinated. Philly isn’t — for now.

The city only knows the vaccination status of employees who voluntarily disclosed it. According to the Mayor’s Office, 5,231 employees reported being vaccinated so far — slightly more than a fifth of the city’s 25,000 employees. In comparison, about 61% of Philadelphia adults are fully vaccinated and about 74% received at least one dose.

Mayor Jim Kenney’s administration has not ruled out imposing a vaccine requirement in the future. But the time to act is now — not because the situation is dire, but to keep it from becoming so.

There is reason to believe that Philadelphia can prevent high rates of community spread of the delta variant. The number of daily new cases in Philadelphia is rising but still very low overall. The average number of new COVID-19 deaths in the past two weeks has been between 0 and 1, the lowest since the fall of 2020.

The trend in new cases is concerning, but vaccination is the best tool against the virus. Even if there are a small number of “breakthrough cases,” they are still dwarfed by the numbers of cases among the unvaccinated — and are less likely to result in hospitalizations and deaths.

A vaccine requirement is especially vital for city employees because of the importance of municipal services during the pandemic. Last summer, trash collection was severely delayed because so many sanitation workers received no personal protective equipment and got sick. A more vaccinated city means fewer residents are at risk of contracting the coronavirus — and that Philadelphia would be able to maintain a greater semblance of normalcy in an outbreak.

» READ MORE: With new Philly mask guidelines, Mayor Kenney needs to lead us through the next chapter of the pandemic | Editorial

Vaccine requirements are becoming more common. The state of New York, New York City, and the state of California all announced similar moves this week. The National Football League has implemented a policy of penalties for teams if games are delayed because of non-vaccinated players testing positive for the coronavirus.

Instead of lagging behind the NFL, our local government should be leading by example.

Any vaccine requirement will take time to put in place, as employers need to give employees the chance to get the vaccine. The University of Pennsylvania gave employees a two-month heads-up. The city should start working with municipal unions to set up a schedule for such a requirement and organize opportunities for workers to get vaccinated.

The time for the city to show leadership is now — it’s up to Philadelphia to join the federal government to set an example for other employers on how they can help save lives and avoid shutdowns.