Modeling Confirms High COVID-19 Vaccination Rates Are Necessary to Reduce Cases, Control Pandemic

Aislinn Antrim, Associate Editor

If half of the US population is vaccinated by the summer rather than the fall, 5.8 million cases of COVID-19 could be prevented.

Maintaining high COVID-19 vaccination rates is essential to determining the course of the pandemic and controlling infection rates, according to findings from 2 recent studies.

In the first study, investigators with the Mayo Clinic found that vaccination rates have been essential to maintain manageable COVID-19 rates. The study was led by investigators Curtis Storlie, PhD, and Sean Dowdy, MD, who developed the computer model for forecasting COVID-19’s impact on hospital usage. Their work has helped guide the Mayo Clinic’s response to the pandemic, and their predictive modeling has been shared with Minnesota public health leadership to help inform critical decisions over the course of the pandemic.1

According to the study, vaccination is key to ending the pandemic. The team’s projections take new variants of the SARS-CoV-2 virus into account, as well as current public health measures and masking standards.1

For instance, vaccinations are making a significant difference in Minnesota, where health care providers have been able to maintain the current level of positive cases and keep it from becoming an emergency.1 The Mayo Clinic researchers estimate that a peak of more than 800 patients would be hospitalized in intensive care units (ICUs) in Minnesota in spring 2021 if no vaccines had been developed. The predicted ICU levels would be more than double the number of COVID-19 patients hospitalized in Minnesota ICUs on December 1, 2020, at the height of the most recent surge last year.1

“It is difficult to untangle how much of this elevated rate of spread right now is due to new variants as opposed to changes in social behavior,” the study authors said in a press release.

However, they said “regardless of the reason, the absence of vaccinations in the current environment would have been likely to result in by far the largest surge to date.”1

According to the press release, if Minnesota had achieved vaccination of 75% of the population by early April, the 7-day average of cases per 100,000 residents, the number of COVID-19 patients hospitalized, and the number of patients in ICUs would decrease dramatically by early July.1

“According to the model, this level of vaccination would completely suppress the growth (even in the face of the recent elevated spread rate) and immediately drive cases and hospitalizations down to very low levels,” the authors said in the press release.1

A second study, published in the Journal of Infectious Diseases, has found that even small increases in vaccination coverage could minimize lost lives, medical costs, and hospitalizations. A team of researchers developed a computer simulation model of the entire United States and the spread of COVID-19 throughout the country. They simulated vaccinating different proportions of the population at different rates with different types of vaccines.2

According to the study, going from 30% vaccination coverage to 40% coverage could save 24.3 million cases and $33.1 billion in direct medical costs and productivity losses. Similarly, going from 50% vaccination coverage to 70% coverage could save 9.5 million cases and $10.8 billion in direct medical costs and productivity losses.2

Furthermore, these higher coverage levels should be achieved as soon as possible, according to the researchers. Speeding up vaccinations to reach a 50% coverage by July instead of October could save an additional 5.8 million cases, 215,790 hospitalizations, 26,370 deaths, $3.5 billion in direct medical costs, and $4.3 billion in productivity losses.2

Getting as many people vaccinated as possible is especially important before winter, according to the study results. The investigators incorporated changes in the transmission of the virus that occurred as the seasons changed in 2020 and projected what may happen in 2021. For example, if 50% of the US population is vaccinated by October 2021 instead of the end of December 2021, 6.6 million cases, 252,260 hospitalizations, 29,380 deaths, $4 billion direct medical costs, and $8 billion productivity losses could be avoided.2

“The results of this study can give policymakers, community leaders, and other decision makers a sense of how much can be invested into vaccinating those who may be harder to get vaccinated,” said lead study author Sarah Bartsch, MPH, in the press release. “Such investments may end up paying for themselves. For example, the potential cost savings exceed the $1.5 billion Biden Administration community outreach and media campaign. Our results show that increasing total vaccination coverage by just 1% could cover the costs of this effort.”2

Finally, the study results showed that increasing vaccination coverage levels is more valuable than simply using vaccines with higher efficacy. Moreover, as more contagious variants circulate, potentially decreasing the efficacy of currently available COVID-19 vaccines, using all options could help address concerns about continuing with the existing vaccines or waiting for an updated version.2

REFERENCE

1. High vaccination rate is key to future course of COVID-19 pandemic, Mayo Clinic computer modeling shows [news release]. Mayo Clinic; April 23, 2021. https://newsnetwork.mayoclinic.org/discussion/high-vaccination-rate-is-key-to-future-course-of-covid-19-pandemic-mayo-clinic-computer-modeling-shows/. Accessed May 10, 2021.

2. Achieving high COVID-19 vaccine coverage levels by summer can prevent millions of cases [news release]. CUNY SPH; May 6, 2021. https://sph.cuny.edu/life-at-sph/news/2021/05/06/vaccine-coverage-prevents-millions/. Accessed May 10, 2021.