Planalp, Colin
Research Fellow

p 612-624-4850
e cplanalp@umn.edu

Vaccinating children may be key to reaching COVID-19 herd immunity

Few states could hit 80% vaccination rate until children are eligible

As more people become vaccinated against COVID-19, it’s understandable that many want to return to “normal.” Recognizing that desire, the U.S. Centers for Disease Control and Prevention (CDC) recently published guidance on activities people can engage in after being fully vaccinated; for instance, those who are fully vaccinated may socialize indoors, without a mask, with other fully vaccinated people.¹

However, as the U.S. still works toward a goal of “herd immunity,” in which a sufficient share of the population has been vaccinated to stem the spread of the virus, the CDC also recommends that everyone—including fully vaccinated individuals—continue to take precautions. For example, people should continue to wear masks and social distance in public, avoid large gatherings, and postpone travel plans until enough people are vaccinated.

While the herd immunity threshold to halt community spread of COVID-19 is yet unknown, experts such as Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, estimate the rate is somewhere between 70-90 percent of the population. The development and authorization of multiple vaccines raises hope for achieving herd immunity, but reaching that goal will be neither fast nor easy.

One major challenge on the path toward herd immunity is that current vaccines are primarily or entirely limited to adults. However, children make up a substantial share of the U.S. population—roughly 22 percent for the country overall, and ranging by state from a low of 18 percent in Vermont to a high of 29 percent in Utah.

State-level population data illustrate the impracticality of reaching herd immunity thresholds until COVID immunization is also broadly available for children. For instance, assuming a 70 percent threshold for COVID, which falls on the lower end of what experts predict, herd immunity would be challenging for most states and almost impossible for others.

Estimated Percentage of State Adult Populations Needed to Reach Total Population Herd Immunity

To reach 70 percent of the overall state population by immunizing only adults, Vermont would have to vaccinate 86 percent of the state’s adult population, while Utah would have to vaccinate 99 percent of its adult population. Achieving those goals would necessitate concerted efforts to overcome historic disparities in distribution of vaccines, as well as nascent inequities in the distribution of COVID vaccines, as SHADAC has documented in other analyses.^2,3,4

As herd immunity targets increase—from 70 percent to 80 percent to 90 percent—reaching herd immunity through only adults ultimately becomes mathematically impossible for all states due to their sizeable numbers of children, who are largely ineligible for vaccination as of yet.

Eventually, as COVID vaccine trials are completed and the immunizations are approved for children, herd immunity will become a tangible and achievable landmark. The U.S. has decades of experience in successfully immunizing its population against communicable diseases. For example, recent estimates from the CDC show that more than 90 percent of eligible children have received vaccines against chickenpox; hepatitis B; polio; and measles, mumps and rubella.⁵

But until COVID vaccines have been deeply distributed among both adults and children, it will likely remain important for people to take continued public health precautions such as social distancing and wearing face masks to slow the spread of the virus, as recommended by the CDC.

Related Reading
Measuring Coronavirus Impacts with the Census Bureau's New Household Pulse Survey: Utilizing the Data and Understanding the Methodology (SHADAC Blog Series)
State-level Flu Vaccination Rates among Key Population Subgroups (50-state profiles) (SHADAC Infographics)
50-State Infographics: A State-level Look at Flu Vaccination Rates among Key Population Subgroups (SHADAC Blog)
Anticipating COVID-19 Vaccination Challenges through Flu Vaccination Patterns (SHADAC Brief)
Ensuring Equity: State Strategies for Monitoring COVID-19 Vaccination Rates by Race and Other Priority Populations (Expert Perspective for State Health & Value Strategies)