We all hope we can reopen schools and colleges this fall, but only if the number of new infections is extremely low and controlled. But the rules of limited engagement will still apply. Students must reduce their contacts by staying in the same small group, limiting interaction outside that group, and wearing face masks in close quarters. That’s critical.

Before we can even consider entering this new world, a new testing strategy must be put into place. Priority needs to be given to areas where we think the virus is most likely circulating, based on surveillance testing. We need millions of tests a day, not the hundreds of thousands of tests being done now. This is achievable, but will require commandeering the large laboratory testing facilities in the country and invoking the Defense Protection Act to assure swabs, reagents, testing equipment and other supplies are at the ready.

Many seniors and vulnerable individuals are wondering when they can go out again. A mass testing program will go a long way to ensure their safety by identifying and isolating individuals in their communities who are transmitting the virus. Even then they need to wear masks, reduce contacts and prioritize when they go out. We also need a public health infrastructure up and running to contact, trace, isolate and prevent infected people from spreading the virus. This will be an enormous undertaking. Hiring and training people to do this contact tracing must begin now.

Likewise, we must muster a wartime effort with the private sector to manufacture enough protective personal gear for all health workers and others who need it, and effective masks for the public. American factories should be using their collective productivity 24/7 to do this.

None of this can be put in place until we see the number of new cases and hospital admissions low enough to give us confidence that we’ve gotten the transmission rate under control and we have the hospital, intensive care and ventilator capacity to handle further outbreaks.

And all this goes away when we have a safe and effective vaccine. Until then, our behavior will control our fate.

David A. Kessler, M.D., is a professor of epidemiology, biostatistics and pediatrics at the University of California, San Francisco. He is a former commissioner of the Food and Drug Administration.

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