Improving your odds in the COVID-19 lottery

The COVID-19 virus has created a public health lottery that everyone is playing, whether they want to or not. The winners in this lottery are those who get infected, so it is a lottery that you do not want to win. 

How does the COVID-19 lottery work?   

Consider the Powerball lottery. A person picks five numbers between 1 and 69, and one number, called the Powerball, between 1 and 26. A ball machine randomly picks five numbers and one Powerball number. How many of your numbers match those picked by the machine will determine whether you win and how much you win.  

The odds of winning the Powerball jackpot are around 292 million to 1. Even getting just the five main numbers correct has odds of just over 11 million to 1. Powerball lotteries operated by state lottery agencies are highly profitable, which means that the biggest losers are the people who play them.  

Suppose that the risk of getting infected with the COVID-19 virus is like playing a public health lottery, but with the more matching numbers you have, the worse your COVID-19 outcome. 

Like Powerball, your ball machine is filled with balls, each labeled with a number. Instead of the ball machine randomly selecting five balls and a Powerball, the machine selects just five balls. Everyone has a ticket with five numbers on it.   

If none of the numbers on your ticket match the balls selected, you lose — which actually means that you win, since you do not get infected.  

If one of your numbers is selected, you get infected, but you either have no symptoms or mild symptoms and fully recover.    

If two of your numbers are selected, you get moderate symptoms, and fully recover.

If three of your numbers are selected, you get severe symptoms and may require hospitalization. You may also experience lingering symptoms like fatigue and sporadic shortness of breath, referred to as post-COVID conditions. 

The big winners (or losers, in this case) are those who match four or five numbers.    

If four of your numbers are selected, you require hospitalization and spend time in an intensive care unit (ICU). If all five of your numbers are selected, you end up succumbing to COVID-19 and dying. The odds of these last two outcomes are small, but they are not zero.   

Not everyone in the population has the same odds of these outcomes. The odds are a function of the number of balls in your personal machine. In general, the more balls in the ball machine, the more likely your ticket will match zero; one or two of the numbers selected gives you better chances of good outcomes if infected. 

Based on a computer model that I built, unvaccinated men over 85 years old have around 10 balls in their machine. For the average person, it is closer to 15. If a person gets vaccinated, it is like having 25 to 40 balls in their ball machine. 

Every action that is taken to reduce your risk of infection equivalently adds balls to your personal ball machine. This includes wearing face coverings indoors when around other people, hand hygiene, good ventilation and physical distancing. The most effective way to add balls to your ball machine is vaccination.  

All these actions reduce your risk of matching three, four, or five numbers, which is when the virus outcomes are poorest. If the virus becomes more contagious or virulent, it effectively removes balls from everyone’s ball machine; if community transmission in your area increases or decreases, balls are removed or added, respectively. 

COVID-19 is a public health lottery that everyone must play. Each of us chooses actions that add or subtract balls from our ball machine, which affects our odds of winning or losing. But this is the one lottery that we want to lose, and the best way to increase our odds of losing is to take the right actions to improve your odds accordingly. 

Sheldon H. Jacobson, Ph.D., is a founder professor of Computer Science at the University of Illinois at Urbana-Champaign, with a background in probability models. He applies his expertise in data-driven risk-based decision-making to evaluate and inform public health policy. Visit http://shj.cs.illinois.edu for more details.