We face a daunting task: The nation must vaccinate an estimated three-fourths of Americans to interrupt coronavirus transmission and stop the spread. Reaching this target by Sept. 1 will require us to fully immunize about 240 million Americans over the next eight months, or 1 million people every day from now until then. Because the only two vaccines approved for use in the United States now require two doses to provide high levels of protection, we may have to double that number.

We have no other choice: In the absence of any real federal coronavirus response, all that remains is the hope to vaccinate the nation. Averting a humanitarian catastrophe and possibly the worst public health disaster in modern U.S. history requires the immediate implementation of a new program to immunize millions. It isn’t too late to get vaccination back on track, but acting now to scale up vaccine delivery is paramount and must become the nation’s top priority.

The first two products of Operation Warp Speed, the Trump administration’s effort to bring vaccines to market quickly, were highly effective in Phase 3 trials. They were loaded onto FedEx and UPS trucks ahead of schedule, reaching the states before the end of 2020. I was a beneficiary, and I’m grateful to have received two doses of the Pfizer-BioNTech vaccine.

But there was no overarching initiative for vaccination, either. The Trump administration delivered vaccines to the states intact and safely frozen.

There are no plans beyond that.

The logistics of catching up starting next week, once President-elect Joe Biden takes office, are staggering. In large metro areas such as Boston, Washington, D.C., and Houston, we need to be vaccinating at least 10,000 people every day for the next eight months to stay on target. We are not even close to that: Since Dec. 15, only 139,000 people have been vaccinated in Massachusetts, 21,000 in Washington and about 105,000 in Harris County, Tex. And no mechanisms are in place to reach our goals. Doing so would require implementing additional infrastructure to vaccinate many people at a time, possibly creating large hubs in outdoor stadiums — Gillette Stadium or Fenway Park in Massachusetts, or Yankee Stadium and Citi Field in New York, for example — to achieve what’s required. The sites would need to be staffed with health professionals, including teams capable of managing patients in the event that someone suffers a severe allergic reaction.

For U.S. adult vaccination programs, we do not have lots of historical precedent to guide us. Mass polio vaccination programs relied on immunizing children, for which schools provide a natural vehicle, although we have successfully mass vaccinated children, teenagers and young adults against meningococcal meningitis following outbreaks in Florida and elsewhere. In that case, we required the active involvement of volunteers and law enforcement officials for crowd control. We will need to explore such approaches for vaccinating against the coronavirus. Achieving herd immunity is not otherwise possible.

In place of an actual plan, we’ll have frantic phone calls to CVS, Walgreens and Sam’s Club by sons and daughters asking whether vaccine is available for their elderly parents. Or similar calls to physicians and other health-care providers.

Of course, nothing is wrong with obtaining adult vaccinations at pharmacy chains or from health-care providers. Over the years, that is where I received my Tdap and Shingrix vaccinations and many annual flu shots. But the reality is that we must implement something more, a high-volume system to safely administer coronavirus vaccinations to everyone who wants one.

That can happen only with extensive — and maybe costly — intervention from the federal government, both for logistics and financial support, to immunize on the order of 10,000 to 20,000 people per day in major metro areas. Setting up vaccination hubs won’t require only space; it also means hiring hundreds or thousands of vaccinators and support staff, and paying for security and parking attendants.

A massive vaccination campaign won’t work with our current fussy and intricate criteria for who gets a shot and when. We learned in 2020 that our health system simply cannot do complicated things. Yes, the Phase 1a rollout for health-care professionals and nursing home residents made sense, but beyond that, we have no mechanism for gate-keeping at scale. There is no obvious path for vaccinating tens of thousands of people while ensuring that the first ones in line qualify by essential occupation or underlying health condition. Confirming such criteria is complicated at best, and it’s probably not even feasible to try under conditions of duress.

We will need additional vaccines. It is unlikely that sufficient amounts of the two mRNA vaccines will be made available in 2021, so the government will have to approve emergency release of adenovirus, particle and recombinant protein vaccines now completing clinical trials. But the unproductive discussions about administering only a single dose of the mRNA vaccines, or delaying the second dose, should stop: That would only ensure failure by reducing the efficacy of the one thing that we know actually works. The recent announcement by the incoming Biden administration about releasing all existing mRNA vaccine doses in stock now should not be interpreted as an endorsement of a single-dose vaccine strategy; rather, it’s a means to immunize as many people as possible now with the first dose, to get more people fully protected earlier once they also receive their second dose.

Finally, we need to communicate these programs in a meaningful way to the American people. Public service announcements will help, but they are not a substitute for frequent and regular communication from government leaders and scientists. The U.S. vaccination program will not go smoothly, even once it gets going faster — some vaccines may turn out not to produce lasting or durable immunity, and they could require third or even fourth boosts. Some virus variants may emerge that partly escape the virus-neutralizing antibodies induced by immunization with the current vaccines. By the summer, we may begin vaccinating adolescents and children. Each time a complication arises, anti-vaccine groups will spread their falsehoods unopposed on the Internet, dominating social media and inflicting great harm in terms of vaccine confidence. This, too, must be addressed.

This disaster in the making was entirely avoidable. By last summer, it was already clear that the Trump administration had declined to launch a national strategy to stop the spread of the virus. The White House did little to slow a massive second surge of infections in the Southern states, or the vast and terrifying third surge that followed and is now causing the deaths of 2,000 to 3,000 Americans every day.

Its only real stated intervention was to eventually vaccinate. Vaccines were coming “momentarily,” we were told, and a four-star military general was appointed to oversee the logistics. However, the reality was that President Trump put us in a precarious position by doing nothing else to fight the virus: In the absence of a national strategy for containment, we have no choice but to vaccinate our way out of this pandemic.

Now the current default path is untenable. We are projected to lose half a million American lives as we head into the second quarter of 2021, and eventually we could eclipse the death toll from the infamous 1918 flu pandemic in the United States. We cannot allow it. Vaccination must become our No. 1 homeland security priority.