A Tough Covid Challenge: Reinforcing Our Wall of Immunity

As pandemic measures unwind, can regular boosters make us safer from a persistent virus?

Dr. Tom Frieden
5 min readMay 8, 2023
Photo Credit: Kaja Reichardt/Unsplash

Covid hasn’t gone away, but it also no longer poses the serious threat to most people today it did in the first months and years after its emergence. Vaccination has saved millions of lives and continues to shield people from the worst effects of the virus. Effective treatments are available and cut the risk of bad outcomes.

Our wall of immunity, built from vaccinations and previous infections, is strongbut it’s far from impervious.

The waning of protection and the unwinding of the public health emergency have raised questions and highlighted lingering challenges. Can a spring booster help? Who is still at high risk of severe Covid now? There are no easy answers.

Lingering challenges

The SARS-CoV-2 virus that causes Covid continues to mutate and evolve. This means that versions of the virus circulating now are quite different from those we faced initially. Because of this, they’re harder for our immune systems to recognize and fight.

The protection our immune systems develop after an infection or vaccination (or both) wanes over time. First, our immune systems lose the ability to prevent an infection — this protection wanes within 2–3 months for most people, and faster for some people. Then, protection against severe illness, hospitalization, and death wanes, generally 4–6 months after vaccination. This is of particular importance for people who are older or medically vulnerable. And although an infection is still less likely to make most of us seriously ill than it was early in the pandemic, when our immune systems were naïve, it remains lethal for many older adults and medically vulnerable people.

Today, many people are no longer focused on how they can avoid Covid. And the sad reality is more than 1,000 people in the United States, and 7,000 globally, died from Covid last week. That’s a steep toll which only may seem like progress because the pandemic has been so awful for so long. Those infected with the virus remain susceptible to long Covid, which can be debilitating. We don’t know nearly enough about the syndrome and especially not enough about how best to treat it.

Boosters — a lasting solution?

Updated Covid vaccine recommendations from CDC may ease some concerns of older adults and medically vulnerable people wondering when they could get another shot. Individuals in those two categories are eligible for a booster shot today if it’s been at least four months since their last one (and two months for immunocompromised people) and are likely to be eligible for another one in the fall. People who have had Covid might wait 3 months after their infection before getting a vaccination.

Anyone 6 years and older who has received one dose of the bivalent vaccine (the fall Omicron booster) is considered up to date on Covid vaccination, regardless of their vaccine history.

If you’re age 65 or older, immunocompromised, or among the 4 in 5 Americans haven’t yet gotten a booster, you should get one now.

To make these recommendations, the FDA and CDC each have advisory committees with experts from around the country including scientists, doctors, and academics. The ACIP, CDC’s advisory committee, takes information from FDA on safety and efficacy and crafts it into guidance for who, when, and why a vaccine should be available. And because the characteristics of the virus continue to change, recommendations for vaccines and treatments should change with them.

The waning of protection and the unwinding of the public health emergency have raised questions and highlighted lingering challenges. Can a spring booster help? Who is still at high risk of severe Covid now? There are no easy answers.

Vaccines will be essential to continue to help us fight Covid, but striking the right balance is a challenge. A spring booster will help protect people with weakened immune systems and those who didn’t receive their fall Omicron booster. Annual boosters may not be enough to drive down deaths and hospitalizations for older or medically vulnerable people. And recommending that everyone get a shot every 4–6 months seems excessive.

One possible future scenario is a recommendation for annual vaccination for most people and twice-yearly vaccination for those at higher risk. But only time will tell. It’s possible that we’ll get longer-lasting vaccines, that the virus will change in surprising ways, or that we will learn more about immunity in ways that change our thinking about vaccination.

On the question of who faces the most risk of hospitalization or death from Covid, the disappointing answer is that we don’t have enough data to know. I wish we knew more. CDC should work with state and local health departments to collect and quickly publish data regarding exactly who is dying from Covid now so we can better protect people with conditions that put them most at risk.

Going forward

The World Health Organization has declared the global health emergency over, but Covid transmission hasn’t yet settled into a pattern that we can predict reliably. Precautions remain helpful for many, and there’s work to do to fix what Covid has broken and exposed in our health system and society.

The deep impact of the pandemic and the challenges we continue to grapple with point to a need for 3 R’s: Renaissance in public health, Robust primary care, and Resilient individuals and communities. Collaboration to improve public health, primary care, and community resilience is essential to build healthier, more productive societies better prepared for future pandemics and other health threats and better structured to promote health now.

Globally, we must strengthen health systems at all levels to address the dangerous aftershocks of the pandemic, such as missed childhood vaccinations and a health care workforce that needs much more support. Global colleagues and I wrote in The Lancet Public Health about the need for epidemic-ready primary health care that can prevent, detect, and respond effectively to disease outbreaks while maintaining routine health services.

It’s not clear how long the current Covid equilibrium will last, even as emergency measures wind down and countries around the world shift their focus to other priorities. We can’t be sure what the future will hold. The Covid vaccine — developed based on years of research and configured in less than 9 months — is the closest thing we have to a silver bullet in this pandemic. But improved public health systems are key to managing existing disease threats and preventing new ones.



Dr. Tom Frieden

President and CEO, Resolve to Save Lives | Former CDC Director and NYC Health Commissioner | Focused on saving lives. twitter.com/drtomfrieden