Last Friday, amidst all the heat, hype, and big bucks that greeted even the most modest advances in Covid-19 vaccine development in the United States, a far more sober assessment came from our friends across the pond: “Why We May Not Get a Coronavirus Vaccine.”

Evidently British restraint, coupled with Boris Johnson’s tangle with Covid, has infused a dose of reality into the country’s expectations of what a Covid vaccine might and might not do. This is a reality check for which the American government is long overdue.

To repeat my own warnings on the subject, the question we must reckon with is not when, but if we will find a Covid vaccine that is safe and effective for everyone. If we acknowledge the reality that the vaccines currently being tested might fail or protect only some of us, what policy choices can our lawmakers and elected officials enact now that will ensure our protection no matter the outcome?

If all vaccines fail, the answer is clear. Use what we know works to radically reduce infection in our populations. Identify those infected, symptomatically or via testing; identify those exposed through rigorous contract tracing; and mandate a period of 14-day controlled isolation for all those exposed. Then, continue the policy indefinitely to prevent re-occurrence during the pandemic. East Asian countries proved that is the best way to drive the infection rate to zero or near zero.

We should all remember the entire pandemic began as a single infection in a faraway country. A single infection at home, absent a vaccine, could restart this terrible cycle.

If the vaccine completely protects only the young and healthy, again, the answer is clear. Vaccinate everyone, without regard to age, economic income, or geography. Urge caution for the elderly and anyone else who may not respond because of preexisting medical conditions. Understanding that the danger of a renewed epidemic is real, continue the policy of identification, contact tracing and mandatory isolation.

If the vaccine partially protects the young and not the elderly, then we will be facing the most likely outcome. Current vaccines may protect the young from dying of lung disease but may not prevent nasal infections and possibly other complications. They may still transmit the virus. The most vulnerable populations will remain at high risk of dying. In that case, we will have no recourse other than to maintain a high level of vigilance and infection control via detection, contract tracing, and isolation.

There is a very real possibility that we will develop effective anti-viral drugs that both cure those ill and prevent infection of those exposed. I recently wrote about the 100 Million Healthy Lives program in Egypt. Over the course of one year, everyone in the country 12 years and older—a total of 65 million people—was screened for hepatitis C infection, a silent condition. Those with active viremia were treated and cured.

Hepatitis C is now eliminated from Egypt. The cost was modest, less than $250 million for the entire program. That is a future we can look forward to if we are fortunate enough to have the drugs to do the job. Even so, until Covid is gone from the face of the earth, the policy of identify, trace and isolate must remain.

Creating sound public policy in the face of uncertainty is difficult, but that it is the job of government. Governments exist to protect us all. Let’s hope that they are up to the challenge.