How More Prompt Action Could Have Saved Thousands of U.S. COVID-19 Deaths

Though the United States saved over 40,000 lives due to COVID-19 from September 2021 to June 2022 from the help of boosters, 29,000 lives could have been saved if the U.S. moved at a faster speed resembling Israel’s booster rollout.

According to a study recently released in Health Affairs, Israel was the first country in the world to launch COVID-19 boosters, in late July 2021, with strong public health messaging.

The booster campaign in Israel successfully turned increasing infection rates associated with the Delta variant, leading to a decrease in hospitalizations and death.

However, the U.S. booster rollout was slower with a rollout in mid-September 2021, and public health messaging was mixed.

Researchers of the study compared each country’s experience to ask the question: How many lives could the U.S. have saved if boosters were authorized sooner?

In attempt to answer this question, a two-step observational approach, utilizing individual-level mortality data and COVID vaccination records for Milwaukee County, Wisconsin, was conducted from 2017 to 2022.

Milwaukee, with a diverse population of 928,000 in 2021, provided vaccination and mortality data for the entire adult population.

Applying the Milwaukee-based data to national data, researchers estimated that among 300,791 COVID deaths in people aged 55 years and older, 56,566 were among vaccinated, booster-eligible individuals, with 52% potentially preventable deaths if operated under an Israeli strategy.

Researchers also explored different scenarios. They estimated potential lives saved if the U.S. booster campaign had matched Israel's uptake speed, considering later initiation, and examined the additional lives lost with a slower U.S. booster authorization.

Weekly analyses were done on non-immunocompromised individuals aged 55 and older, categorized by age groups. Researchers then factored a four-week lag after vaccination to consider vaccine effectiveness against death.

Israeli vaccination rates came from TIMNA, while Milwaukee data relied on linked vaccination and mortality records.

Using a Markov model with states representing vaccination status and COVID death, researchers looked at transition probabilities based on CDC data and mortality risk estimates specific to Milwaukee.

The model effectively replicated actual U.S. data, with a 1.5% difference in predicted deaths (296,412) compared to actual deaths (300,791) over the study period.

A breakdown by vaccination status revealed 51% were unvaccinated, 14% were one-dose recipients, 29% were fully vaccinated and 5% were booster recipients.

The study estimated 77,156 deaths among vaccinated individuals without a booster and 28,821 deaths with a booster.

Data revealed that a faster booster rollout could have potentially saved approximately 29,418 lives if the U.S. matched Israel's pace.

Delaying booster approval cost around 800 lives per week, but even an eight-week delay would have saved 22,900 lives, the study found.

Overall, booster authorization ultimately saved 41,639 lives by June 30, 2022.

Additionally, it was found weekly estimates revealed notable effects during the Delta-Omicron wave in the end of 2021 and early 2022. The benefits of prompt action and the drawbacks of delayed responses leveled as the Delta-Omicron wave eased off in the spring of 2022.

Delayed booster authorization would have left more people vulnerable during the Omicron period.

Researchers noted limitations within the study.

Some of these limitations include the limited sample size in Milwaukee that led to uncertainties in their estimates, potentially not representative of the entire U.S.

Researchers also focused on Pfizer and Moderna recipients, acknowledging potential variations for Johnson & Johnson.

They also noted their assumption that boosters wouldn't alter infection rates may have led to “conservative projections,” due to challenges in modeling.

Though researchers didn't specifically measure the effects on various racial and ethnic groups, higher COVID-19 mortality rates in these populations suggest the timing of booster shots might have a bigger impact on them.