Delta & Breakthrough Infections in the Vaccinated: Should You Worry?

FRIDAY, Aug. 13, 2021 -- Masks are making an unwanted comeback in many parts of the United States, after new data showing that fully vaccinated people with "breakthrough" coronavirus infections carry enough virus in their bodies to pose a potential risk to the unvaccinated.

But these breakthrough infections — which have become slightly more common with the highly transmissible Delta variant — pose little to no threat to most vaccinated folks who are unlucky enough to get them, infectious disease experts stressed.

Nearly all breakthrough COVID-19 cases occurring in the United States are symptom-free or mild illnesses that can be treated at home, if they require treatment at all, said Dr. Amesh Adalja, a senior scholar with the Johns Hopkins Center for Health Security, in Baltimore.

"The fact that the breakthrough infections are mild is evidence not of the vaccine's failing, but of the vaccine succeeding, because vaccines aren't force fields or bug zappers," Adalja said. "They are meant to minimize the symptoms that could occur with a breakthrough infection."

Instead, vaccinated folks are being asked to mask up to protect the unvaccinated, as well as themselves, so that enough hospital beds remain available for everyone.

The average number of people hospitalized daily for COVID-19 infection during the last week of July alone outpaced the total number of vaccinated people who have ever been hospitalized for a breakthrough infection, the U.S. Centers for Disease Control and Prevention noted.

The CDC estimates that 7,707 people per day, on average, were hospitalized with COVID-19 infections from July 28 through Aug. 3, 2021.

By comparison, all hospitalizations from breakthrough COVID-19 infections that have been reported to the CDC from the beginning of the U.S. vaccination program through Aug. 2 amount to just 7,101.

There also have been 1,507 deaths reported from breakthrough infections among the vaccinated -- just 0.6% of the nearly 241,100 total COVID-19 deaths that have occurred so far in 2021, CDC data show.

The COVID-19 vaccines now available in the United States were not designed to completely prevent infection, Adalja explained. Rather, they were intended to prevent severe illness that could land someone in the hospital or kill them; essentially taming a tiger of an infection down into a kitten.

A growing pile of data suggests that the vaccines are, in fact, working as intended:

• Fully immunized people account for less than 5% of hospitalizations and less than 6% of deaths from COVID-19, according to a New York Times analysis of data from 40 states.
• NBC News reports 125,682 breakthrough cases in 38 states, represent less than 0.08% of the 164.2 million-plus people who have been fully vaccinated since the start of the year, or about one in every 1,300.

The whole goal of vaccination was to make COVID-19 into just another seasonal bug, Adalja said. That's how it's working out for those who've gotten the full jab.

"What we've always tried to do with COVID-19 is make it a more manageable respiratory virus, like ones we deal with day in and day out," Adalja said. "That's what the vaccine is accomplishing. Breakthrough infections are going to be something we hear about and see. I think virtually everybody's going to get a breakthrough infection at some point," he added.

"The fact is, when you get those breakthrough infections it's going to be mild because of the vaccines, and that's all we've ever asked of the vaccines," Adalja concluded.

In fact, some experts suggest a mild breakthrough case could actually be helpful, further boosting and improving your immunity against COVID-19. The illness, though blunted by the vaccine, provides the immune system a chance to learn more about the coronavirus and strengthen its defenses.

The reason the CDC changed its tune in July and urged people to start wearing masks indoors again, at least in high-transmission areas, had nothing to do with the threat of breakthrough infections to vaccinated people.

Instead, the agency was responding to new data suggesting that people with breakthrough infections could carry viral loads as high as those of infected people with COVID-19.

Thanks to the vaccine, these people most often suffer only mild illness if any at all, despite the large amount of virus in their bodies.

But those large viral loads make it more likely that they could spread COVID-19 to unvaccinated people in their midst — and those unprotected folks are at greater risk of hospitalization and death from the highly infectious Delta variant.

Vaccinated people who are resentful about having to don masks again to protect their unvaccinated neighbors should consider it something of an insurance policy for their own access to health care, said Dr. Preeti Malani, an infectious disease professor and chief health officer for the University of Michigan.

"Something that gets lost in all this is when your health care system is overwhelmed by COVID cases, if you fall and break your leg or if you develop appendicitis or you have some other issue that requires care, it becomes more complicated to receive that care," Malani pointed out.

She said she's concerned about breakthrough infections in some vulnerable groups, mainly seniors or folks with conditions that compromise their immune system.

"We are seeing more people hospitalized who have breakthrough [infections], but these have tended to be individuals who were older. I saw someone who was 108, a couple of weeks ago. The people being hospitalized tend to be individuals who have more underlying health conditions," Malani said.

"For healthy people, overwhelmingly [breakthrough infections] are something that is an inconvenience and doesn't have long-lasting effects," she added.

Still, until vaccination rates approach herd immunity, COVID-19 surges in specific regions will continue to strain hospital resources and make prevention strategies like masking necessary, Malani said.

"Vaccination still is the only way out of this, but now what is clear is that more people need to be vaccinated," Malani said of the Delta surge. "At this point, what I'm recommending to my friends and family is in indoor crowded public spaces, wear a mask. It's not a big deal."