How breakthrough infection rates for vaccines will make a difference

The Centers for Disease Control and Prevention (CDC) now recommends that people who are fully vaccinated against COVID-19 can resume activities akin to what they enjoyed prior to the pandemic. With over 146 million people fully vaccinated, this means that well over one-half of all those 12 years of age and older can safely enjoy social and work activity with negligible risk of infection. 

But negligible risk is not-zero risk. Breakthrough infections, those that occur with people fully vaccinated, quantify such risk.   

As of April 30 , the CDC reported over 10,000 breakthrough infections out of over 100 million people fully vaccinated. Given that many such infections are asymptomatic or with mild symptoms, hence never detected, this value is likely significantly lower than the actual number of such infections. As such, the CDC stopped updating this data and began to report hospitalization and deaths amongst breakthrough infections — data that are easier to track.  

As of June 8, the CDC reported around 3,300 hospitalizations amongst the 140 million people fully vaccinated, a rate of one hospitalization for every 42,000 people. They also report a rate of one death for every 230,000 people. The CDC adds that some of the hospitalizations and deaths were likely unrelated to COVID-19, even though these people tested positive, which would make the breakthrough infection hospitalization and death rates even more favorable.    

The low breakthrough infection hospitalization and death rates are evidence that the COVID-19 vaccines are protecting people. Coupled with the low adverse event rates associated with the vaccines makes them a noteworthy public health success story. 

But the story does not end there. 

With three vaccines available (Pfizer, Moderna and Johnson & Johnson), and more on the way (like the Novavax vaccine), the CDC must take the next logical step and report breakthrough infection rates partitioned by each vaccine manufacturer. Given that the Pfizer and Moderna vaccines use the same messenger RNA (mRNA) technology, they are likely experiencing similar breakthrough infection hospitalization and death rates. Are such rates higher or lower than those for the Johnson & Johnson vaccine? 

It is understandable that if any one vaccine should have a less favorable breakthrough infection hospitalization and death rates, people might not want to take the vaccine, effectively ending its use in the nation, even if their absolute baseline rates are acceptable. However, the CDC has a responsibility to share such data with the public, since hiding the information will create controversy and credibility issues when it invariably becomes public in the future. 

With over 30 percent of the adult population continuing to be COVID-19 vaccine-hesitant, data transparency on the effectiveness of each COVID-19 vaccine is critical to get to 70 to 90 percent of the population fully vaccinated. Fully disclosing breakthrough infection data partitioned by each vaccine manufacturer may make one vaccine more attractive than the others in the eyes of the public, and possibly devalue one or more vaccines to the point that it will no longer be desirable. That is a byproduct of a free market system, where the most favorable products gain the greatest market share. 

The good news is that all three vaccine manufacturers have sufficient capacity to meet the remaining needs in our nation and, in time, the rest of the world. Even with the federal government acting as the sole payer for the COVID-19 vaccines, when given choices, people will choose the product that offers the best value and qualities. Breakthrough infection hospitalization and death rates provide objective efficacy measures that can help inform those who remain vaccine-hesitant. 

Expecting all three vaccines to yield identical efficacy profiles is naïve. With three vaccines available, and more in the pipeline for FDA approval, breakthrough infection hospitalization and death rates can provide a basis for choosing. Transparency with such data is critical to reinforce credibility of the CDC and their role in leading our nation forward to a safe and secure public health environment for all.   

Sheldon H. Jacobson, PhD, is a founder professor of Computer Science at the University of Illinois at Urbana-Champaign. He applies his expertise in data-driven risk-based decision-making to evaluate and inform public health policy.