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To Boost Or Not To Boost

To boost, or not to boost: that is the question:

Whether 'tis nobler in the lungs to suffer

The slings and arrows of an outrageous virus,

Or to take one more shot against a sea of troubles

The highly contagious BA.5 variant has resulted in a surprisingly large number of infections, even among the vaccinated and boosted. And another wave of infections in the Autumn is likely. Given that we all prefer to stay well, how important is it to get another booster?

Fortunately, deaths and severe cases of COVID-19 are greatly reduced from their peaks as most Americans have had vaccination, infection, or both. But the US is still (at the time of this writing) experiencing an average of 500 deaths per day, a rate that is on track to kill more Americans this year than car accidents, colon cancer, and influenza combined!

It might seem like our vaccines no longer offer much protection and, unfortunately, when it comes to infection, this is true. But when it comes to hospitalization and death, our vaccines continue to deliver. For those who qualify, a booster is likely to confer health advantages since booster eligibility is based on research on populations most likely to benefit. Although a bivalent vaccine booster that includes an Omicron subvariant will soon be available, public health professionals stress not waiting if you qualify for a booster now, especially if you are 50 years old or older. Increasing age is a potent risk factor for severe COVID-19.

How much do boosters add to existing protection from vaccines and/or infection?

It depends. It depends on: the time elapsed since the last shot, underlying conditions, past exposure to other coronaviruses, the circulating variant, etc. From a public health perspective, the most impactful and actionable factor is age. Older age is a powerful and easily identifiable risk factor. Current evidence supports it being a primary focus of public health campaigns that seek to reduce hospitalizations and deaths from COVID-19. A study conducted by the Kaiser Family Foundation* concluded that during the early 2022 surge of the Omicron variant, COVID-19 was the leading cause of death for Americans aged 45-84 years old.

To illustrate how much age matters, a client asked Data-Driven to look

at the burden of death in those aged 50+ compared to those under age 50.

The difference is dramatic.

While individuals aged 50+ represent only 36% of the entire US population,

they account for over 89% of COVID-19 deaths in the United States.

Yet looking at the number of deaths does not take into account that a younger person who dies has been robbed of many more years of life. In a second analysis, we accounted not only for the number of lives lost but also the years of potential life lost, referred to in public health parlance as “YPLL”.

For this second analysis (details of which are located here for you math nerds) we looked at the mortality rate and YPLL by vaccination status (fully vaccinated versus not). There were 17,667 deaths in the group under age 50 attributable to inadequate vaccination, compared to 72,833 in the group aged 50+. What we found next was fascinating. Despite the years of potential life in the younger group being vastly greater, and the fact that a majority of Americans are younger than 50 years old, when you multiply the number of lives lost by the average expected years of remaining life, the 50+ under-vaccinated group would have had a whopping 1.4 million potential years lost due to inadequate vaccination compared to 802,000 in the under 50 population.

As we age, we experience immune senescence.

Just like our minds, our immune system is not quite as sharp as it once was.

To aid our minds, we can write a post-it note to remember that upcoming event. Similarly, we can get an extra shot to remind our immune system to recognize and fight the SARS-CoV-2 virus.

Because available data from the Centers for Disease Control and Prevention (CDC) used in the YPLL analysis did not distinguish between 2, 3, or 4 shots, we looked at available studies to assess the impact of boosters (specifically 3rd and 4th doses) on death as compared to deaths among those having only the primary two-dose mRNA vaccination. The results of these studies are highly variable, with much of the variation arising from which variant was active at the time of the study (e.g., Delta vs. Omicron) and the variation in the length of time since the last shot. The studies report the benefit of a third dose (1st booster) is a 20%-90% reduction in mortality or severe disease, and the benefit of a fourth shot (2nd booster) as compared to the third shot is a 14% to 71% reduction in mortality or severe disease. This is a wide variation and there is no perfect apples-to-apples comparison here, but there is a consistent pattern evident across all studies: the greatest beneficiaries of boosters are people aged 50+.

Focusing on encouraging vaccinated, unboosted individuals age 50 and older to get boosted is a worthy effort. Someone who has not yet been vaccinated nearly 15 months after vaccines first became available is not likely to be vaccinated now, much less, to get boosted. Yet even among the vaccinated, substantial gaps remain in the US population aged 65+, with only 70% of those aged 65+ who were fully vaccinated getting a booster, and only 39% of those who got a first booster opting for a second one.

This is a real opportunity to encourage boosters, especially among older Americans. For Public Health officials who are looking to focus their efforts: encouraging and facilitating boosters for older adults is an opportunity likely to pay off in lives saved.

Each of us can play a role. All of us will need boosters over time to maintain our immunity. And one day, we may well have a vaccine that covers coronaviruses more broadly allowing us to stay ahead of a shape-shifting virus. But until that day is here, encouraging someone aged 50+ to remain up-to-date on boosters could make a difference if (or increasingly, when) they get COVID. Discussions with older friends and family, offering a neighbor who does not drive a ride to get a booster, and staying up-to-date on your own boosters (especially if you are age 50+) have the potential to reduce deaths, decrease hospital strain, and protect future years of life from this virus.

* Ortaliza, J., Amin, K. & Cox, C. COVID-19 leading cause of death ranking. Peterson-KFF Health System Tracker

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