Iowa infection experts: Delta is different — COVID-19 breakthrough infections explained

‘If I can still be infected, why get vaccinated?’ The key is in your body’s response.

After the Centers for Disease Control and Prevention (CDC) recommended loosening safety measures in May, their new recommendation to return to masking in public indoor settings may feel like a confusing change of direction. The guidance has changed because the situation has changed.

The delta variant, which is now causing the vast majority of COVID-19 cases in the U.S., is fundamentally different from the earlier versions of the virus.

What makes delta different

Compared to previous strains, the delta variant is better at latching onto cells in the nose and airway.

Once inside a cell, the variant also appears to be better at creating copies of itself (a virus’ ultimate goal), meaning the variant can quickly reproduce vast quantities of viral particles.

These new particles can either infect more cells inside the infected person — causing sickness — or can be shed from the nose and mouth and infect other people.

It is for these reasons that the delta variant is much more contagious than previous versions of the virus.

The guidance has changed because the situation has changed.

— Daniel Diekema, Melanie Wellington and Stephanie Holley

These new particles can either infect more cells inside the infected person—causing sickness—or can be shed from the nose and mouth and infect other people.

It is for these reasons that the delta variant is much more contagious than previous versions of the virus.

‘Breakthrough’ cases broken down

Simply put, breakthrough cases occur when vaccinated individuals contract the disease they’ve been vaccinated against. While that may initially sound startling, breakthrough cases are expected since no vaccine is 100 percent effective at preventing infection.

In general, breakthrough cases are rare. The rate of breakthrough cases among fully vaccinated individuals is between 0.01 and 0.29%, according to the Kaiser Family Foundation research project, which is currently tracking the public’s attitudes and experiences with COVID-19 vaccinations.

However, even if you are fully vaccinated, if you are exposed to a large dose of virus from an infected person, the virus will have an opportunity to infect your nasal cells and start to copy itself. As such, it may be possible for you to spread COVID-19 to others, even if you do not become symptomatic yourself. Therefore, it’s best to maintain safety practices like mask wearing, social distancing, and hand hygiene whenever possible.

If I can still be infected, why get vaccinated?

The key is in your body’s response.

If you are vaccinated, your immune system is primed to be hypervigilant for this invader and has the tools to rapidly shut down the infection and clear the virus.

If you do get infected with COVID-19, you may have some mild symptoms and you may be able to infect other people. But it’s highly unlikely you’ll get very sick, and even more unlikely that you’ll die from the virus.

In fact, the rate at which vaccinated individuals are dying from COVID-19 is close to zero in all but two states reporting numbers — Michigan and Arkansas — where the rate is 0.1%.

If you are unvaccinated, your immune system does not have that head start on the virus. The alarm and response process of your body’s defenses are much slower, less targeted, and less effective, which means it takes longer for your immune system to react to the virus. In this case, while your body is taking time to respond, the delta variant is efficiently infecting cells and creating copies.

In the race between your immune system’s efforts to eliminate the virus and the virus’s infectious power, the delta variant has a serious advantage.

The good news

Fortunately, despite the delta variant’s supercharged nature, the tools we’ve been using to defeat earlier versions of the virus are still effective. The vaccines provide excellent protection against serious illness, hospitalization, and death.

In addition, masks, social distancing, and hand washing all prevent the variant from spreading from person-to-person, which helps protect members of our community who can’t be vaccinated, like younger children.

When we use all these tools, we protect individuals and make our whole community safer for everyone.

This editorial was published in The Gazette on Aug. 24, 2021.

Daniel Diekema, MD, MS, and Melanie Wellington, MD, PhD, are infectious disease specialists at University of Iowa Health Care. Stephanie Holley, MBA, BSN, RN, CIC, FAPIC is an infection preventionist.