ADVERTISEMENT

The Case for a Covid Vaccine Lottery

Hopes for a Covid-19 vaccine breakthrough by the holidays have never been higher.

The Case for a Covid Vaccine Lottery
A lab technician handles a bottle containing growth media during coronavirus vaccine research in Vienna. (Photographer: Akos Stiller/Bloomberg)

Hopes for a Covid-19 vaccine breakthrough by the holidays have never been higher, with Pfizer reporting that its vaccine prevented 90% of infections in trials. A vaccine should be available in early 2021 – or possibly earlier – if Pfizer and other strong candidates continuing large-scale clinical trials around the world receive an emergency use authorization.

The big question is daunting: Who should be vaccinated first? Distributing the vaccine quickly will require overcoming numerous ethical and logistical challenges. And it is complicated by a stubborn fact: We won't have enough for everyone right away. But if we allocate the limited supply with a lottery mechanism, we could keep the process fair and also produce valuable new information about vaccine safety and efficacy.

The National Academy of Sciences has proposed a four-phase framework that puts those at especially high risk at the front of the line: health workers, first-responders, older adults living in nursing homes, and people with comorbidities that make the risks associated with Covid-19 infection far greater. Up next would be K-12 teachers, critical workers in high-risk settings like public transit, and those at moderately high-risk, among others. The third phase includes young adults and children and other workers at increased risk -- followed by everyone else in phase four.

Vaccinating health care workers, first-responders, and adults in nursing homes makes good sense both because those groups are at risk themselves and because they are at high risk of transmitting the disease to others. But there is another reason to start with them: logistics. Two vaccines likely to be approved first in the U.S. -- the Moderna and Pfizer vaccines -- both require cold storage. The Moderna vaccine can be stored in ordinary freezers but the Pfizer vaccine will be shipped from a giant distribution center in Kalamazoo, Michigan, using a custom-built "cool box" that stores 1,000 to 5,000 doses for up to 10 days at -94 degrees Fahrenheit. (That's substantially lower than the average temperature in Antarctica.) We don’t want any vaccine to be wasted, especially in the first phase. And limiting distribution to a small number of known, well-resourced sites such as hospitals, fire and police stations and nursing homes will make it easier to handle the requirements of cold storage. 

But even the first-phase rollout requires tough choices on distribution. The NAS estimates that there are 16 million people working in health care, 2.1 million first-responders, and also 2.1 million elderly people living in nursing homes and other residential facilities. We won’t have that many doses available in the first weeks after vaccine approval.

When potential vaccine recipients have equal claims according to our ethical principles and estimates of risk, a natural – and fair – way to choose recipients would be to use a lottery. That way, everyone with an equal claim to the vaccine has the same chance of receiving it. A team of economists at MIT and Boston College have recently designed a way of organizing these sorts of lotteries. And their system has already helped ration Covid-19 treatments such as the anti-viral drug remdesivir.

To further simplify the logistical challenges of distributing the vaccine, it might make sense to run such a lottery by place rather than by individual. Each hospital, fire station, police station and nursing home would be entered into the lottery -- weighted according to the number of individuals at each place. The lottery would then determine the order in which those sites would receive vaccines.

Serving places in tranches has other important benefits. First, it would reduce the number of locations on the initial list, making the entire delivery effort more manageable. As more vaccine doses become available and distribution logistics improve, the rollout would expand. 

Second, a lottery would let scientists gather more information about the efficacy and safety of a vaccine as the vaccination plan proceeds.

The U.S. clinical trials for Covid-19 vaccines that are currently running typically compare 15,000 to 20,000 people who got the vaccine with 15,000 to 20,000 people who received a placebo. But these trials can take months to reach a conclusion. Statistical comparisons require waiting until enough people are exposed to the virus in the ordinary business of their lives.

If we allocate a vaccine by lottery, we implicitly create a very large randomized trial. For example, if we have 5 million doses ready to go upon approval, then we can vaccinate one quarter of the first-wave group and compare their outcomes with those in the 15 million strong unvaccinated group. That's exactly the type of randomization we would need for a clinical trial, and with millions of people, it will quickly become clear how well the vaccine is working among different subgroups. In addition to improving our understanding of the vaccines themselves, that will help us target vaccine distribution better in future rounds. The randomization of remdesivir is already producing similar data which could help to guide future treatment decisions.

A vaccine lottery is a fair, logistically efficient, and informative method of distributing a vaccine. Lotteries are also reasonably straightforward to implement. The main issue would be to ensure that the lottery process is clear and transparent -- and thus trustworthy. We could also impose some set of geographic balance constraints so that whole areas or regions aren't accidentally left out as a consequence of randomization.

And of course, the goal would be to wind down allocation by lottery and begin widespread distribution as quickly as possible. The faster we can produce enough doses for everyone, the faster we all win.

And of course, whether you're in the control or treatment group is determined at random.

Parag Pathak, the MIT economist involved in the lottery design proposal, has used similar empirical methods in evaluating student outcomes under lottery-based school choice programs.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Scott Duke Kominers is the MBA Class of 1960 Associate Professor of Business Administration at Harvard Business School, and a faculty affiliate of the Harvard Department of Economics. Previously, he was a junior fellow at the Harvard Society of Fellows and the inaugural research scholar at the Becker Friedman Institute for Research in Economics at the University of Chicago.

Alex Tabarrok is the Bartley J. Madden Chair in Economics at the Mercatus Center at George Mason University.

©2020 Bloomberg L.P.