How Many Might Die Even With a COVID Vaccine?

— Some grim back-of-the-envelope math

A photo of a nuclear weapon test by the U.S. military at Bikini Atoll, Micronesia, on 25 July 1946

On July 16, 1945, the U.S. performed the first atomic bomb test in New Mexico. As the blast wave reached Enrico Fermi, the noted physicist and inventor of the world's first nuclear reactor, who was among those watching the explosion some 10 miles away, he dropped bits of paper in order to see how far they would be blown. Fermi reasoned that the distance traveled by the paper could be used to make a quick calculation of the bomb energy yield.

His estimation was 10 kilotons of TNT. The actual energy of the blast was 18.6 kilotons of TNT.

Fermi's quick calculation was within an order of magnitude and therefore within the mathematics of such things. His estimate was impressive. Fermi was famous for many things, but his bits-of-paper trick cemented his fame in what is now referred to as a back-of-the-envelope calculation: the use of estimated or rounded numbers to make rapid ballpark calculations, usually done on a scrap of paper like the back of an envelope.

Americans consistently score low on tests for mathematics. Most Americans consider themselves bad at math and nearly one in five adults suffer from high levels of math anxiety. This is a particularly bad time to be bad at math as we try to make sense of numbers about infection and death by COVID-19.

What Fermi understood is that the real test of math aptitude is the ability to logically estimate. The trick is to break down a seemingly complex equation into smaller parts where the number becomes manageable and relatable.

This is particularly important when the number is really big or really small. What Fermi was actually contemplating with falling bits of paper was the number of people that the bomb would kill.

Recently, Pfizer announced it had a vaccine that is looking like it will be 95% effective against COVID-19. Pfizer, like Fermi, is also thinking about death.

Sometimes an estimation needs a little more background and an understanding of what is at stake. Census data from 2019 estimated the U.S. population at 328.2 million people. We know that about 10 million people in the U.S. have so far contracted COVID and we will assume that prior infections confer immunity and those individuals will not be vaccinated. We can now work with the total population uninfected and unvaccinated to be 318.2 million people.

Many people have said they would refuse a COVID vaccine, and this position, known as vaccine hesitancy, makes it difficult to predict how many people would actually accept a COVID vaccine. For DTP (diphtheria, tetanus, pertussis), a required vaccine, the vaccine rate was 83% of the target population. Polio vaccine uptake was 92.7%. These are long-standing and generally well-accepted vaccines, but for other equally effective vaccines, the vaccine acceptance rate is actually falling.

Let's assume a relatively high rate of 80% uptake for a new COVID vaccine. This means 20% of 318 million people won't get vaccinated -- about 64 million people. Recall that the Pfizer vaccine is claimed to be 95% effective, so 5% of the vaccinated population will get no benefit and will still be at risk for catching COVID-19. The number of the original vaccinated population that will get no benefit is 13 million and when we add this to 64 million unvaccinated people, we get 77 million people.

COVID-19 does not kill everyone who becomes infected. The amount of killing is called the infection fatality rate and for COVID-19, that number has been estimated to be 0.65%, but may be as high as 2%. If every unvaccinated or ineffectively vaccinated person still got COVID-19, the number of Americans that would still die would range from 500,000 to two million -- and that's with a vaccine that is 95% effective.

To put that into perspective, that means COVID-19 would kill the equivalent of every single person in a city the size of Tampa, Miami, Long Beach, or Minneapolis -- or even in a city as large as Phoenix, San Diego, or Philadelphia.

We have left off important information from our back-of-the-envelope equation: How long will it take to vaccinate 254 million people? How long will it take to make enough vaccine doses for 254 million people?

In 1972, smallpox was considered eradicated in Europe. In March of that year, the former country of Yugoslavia suffered an outbreak. The government sprang into action and reacted swiftly. On March 16, 1972, martial law was declared, population movement was severely restricted, and in effect, the entire country was placed under quarantine. The army was used to enforce the quarantine and over a period of approximately 3 months, the entire population of 18 million was vaccinated and the outbreak ended.

Of course, 18 million is a much smaller number than 254 million and I doubt Americans would look kindly on the imposition of martial law for months and months while we carry out vaccinations. As a result, we can expect that our back-of-the-envelope calculation, which assumes mass, instantaneous vaccination, actually underestimates the number of people still vulnerable to COVID-19.

There are other complications: Moderna's and Pfizer's vaccines use mRNA technology, which requires very cold storage with dry ice. We now learn that although the toilet paper shortage is under control, the dry ice shortage is getting worse. Moderna claims its mRNA vaccine only needs more conventional freezer and refrigeration temperatures.

To produce the needed quantity of vaccines is no small feat and might require a level of commitment that up until now we have failed to achieve.

We must also consider who will benefit from this vaccine aside from those whose lives are saved. It was recently reported that Pfizer CEO Albert Bourla sold 62% of his stock in the company on the same day the company announced the results of its COVID-19 vaccine trial. The value of his stock sell-off was about $5.6 million earned in a single day. Others in the company also sold stock and earned millions of dollars.

In 2018, the median individual income in the U.S. was $33,706 per year. It would take that person with that income about 169 years to earn $5.6 million dollars.

The lived reality of COVID-19 is that it has become a new cause of premature death. To get a sense of how many Americans have died so far from COVID-19, you would need to add up all the American deaths in the Korean War, the Vietnam War, and the Iraq and Afghanistan Wars, as well as the number of people killed annually in car accidents and by firearms, as well as the number of people killed annually by the flu.

A 95% effective vaccine will likely reduce the number of people killed by COVID-19, but that will not be nearly enough to bring death by COVID-19 to a halt. In order to do that, we will likely need a plan of action far beyond what to this point we have been willing to do.

The announcement of the development of 95% effective vaccines is good news, but it is no cause for celebration. Even with a perfect, instantaneous rollout, hundreds of thousands of people would continue to die.

At the end of the day, the real tragedy might be how little we did for so long and how we can abide 260,000 deaths in this country so far and not really feel it.

Joel Zivot, MD, is at Emory University School of Medicine in Atlanta. His clinical expertise and research interests include care of critically ill patients in the OR and ICU, education, and scholarly work in bioethics, the anthropology of conflict resolution, pharmaco-economics, and a variety of topics related to anesthesiology/critical care monitoring and practice.