Coronavirus Chronicles

What to Know about the Delta Variant and Breakthrough Cases in Seattle

The most frustrating phase of the pandemic yet is roiling our reopening.

By Benjamin Cassidy August 19, 2021

A “hot vax summer” sounds a lot more exciting than a summer of risk management, but the latter is what we now find ourselves in, even in the very vaccinated city of Seattle.

Both locally and nationally, the Delta variant of the coronavirus has caused Covid cases and hospitalizations to surge, dimming visions of a rollicking reopening. Last week, with breakthrough cases and hospitalizations climbing, the U.S. announced that moderately to severely immunocompromised people can now receive an additional mRNA shot. On Wednesday, president Joe Biden’s administration said that booster jabs would be available for people eight months post–full vaccination, with health care workers and older folks first in line this September. In Washington, governor Jay Inslee reinstated an indoor mask mandate and extended vaccination requirements to school teachers and staffers.

Naturally, all of these measures have raised questions about the Delta variant, children's safety, and vaccines.

What is Delta?

A word that once evoked frat parties and flights to Atlanta is now linked to a coronavirus strain that is ruining our reopening. Or, more accurately, it’s ruining our reopening because people who delayed or refused vaccination allowed it to spread in the U.S.

Delta is now the most common coronavirus variant, which is to say it has mutated from prior forms to infect cells. Unlike other variants, Delta might be as contagious as chicken pox, spreading faster and causing more infections. The CDC says it’s at least two times more contagious than its predecessors. Though the variant first surfaced in India back in December, it wasn’t until this summer that it became the dominant coronavirus strain in Washington. In late July, more than 95 percent of cases in the state were of the Delta variety; it’s probably closer to 98 percent now, per yesterday’s press conference in Olympia.

How does the Delta variant affect vaccinated and unvaccinated people?

Delta is devastating for the unvaccinated among us; there’s some evidence it causes more severe illness than previous strains for those without shots, the CDC reports. But it can still infect vaccinated people.

What is a breakthrough case?

For Covid-19 purposes, when a fully vaccinated person tests positive for the disease two weeks or more after receiving their final shot, they count as a breakthrough case. If they start feeling symptoms after their second shot but before that 14-day period is up, they’re not considered a breakthrough case, as they’re still building protection against the disease during that time.

How common are breakthrough cases in Washington?

This is difficult to say for certain because the state’s Department of Health sometimes identifies breakthrough cases long after a positive test is first documented; each Covid-19 specimen must be sequenced and analyzed, which can take a while. But according to the DOH’s most recent breakthrough surveillance report, there were 5,879 confirmed breakthrough Covid cases between January 17 and July 31 in Washington. Of course, people are more likely to go get tested if they’re feeling sick, so some asymptomatic cases likely go undetected.

Still, even those invisible infections wouldn’t give us the full picture. An important piece of context is missing in the state’s report: the number of people fully vaccinated as of July 31. Upon request, the state couldn’t provide that data point, instead pointing to the number of doses administered (8,194,645). Currently, somewhere north of four million people are fully vaccinated statewide. Even if we cut that figure to 3.5 million, the rate of breakthrough cases in fully vaccinated people would still be well under 1 percent. But again, both the numerator and denominator are fuzzy here, and cases have continued to rise since July 31. Assume it's much higher than we can say for sure right now.

About those graph curves. They’re rising like it’s winter again. So those are basically all unvaccinated people, as far as we know?

Seems that way, with the caveat that breakthrough case IDs are still rolling in. From February 1 of this year through August 10, 93.7 percent of the state’s cases were not fully vaccinated (91.8 percent in King County through July). Through August 3, 94.5 percent of those hospitalized were not fully vaxxed. And as of July 20, 92.9 percent of those who have died of Covid-19 since February 1 were not fully vaccinated.

While those graph curves may look similar to those during the brutal winter wave, focusing on the negative space above the undulating lines distinguishes this phase from the worst one. Last year, we had nothing to stop those curves from going up and up and up as the vaccine rollout crawled. Now we have three widely available shots that, even as they lose some stamina (more on that later), are still more effective than many experts could have ever hoped.

Yes, but breakthrough cases are climbing. How severe have they been in Washington?

Generally not severe. About 88 percent of confirmed breakthrough cases reported Covid symptoms (again, which is likely an overrepresentation since people generally wait until they’re sick to get tested), but only about 7 percent were hospitalized. As of July 31, 66 fully vaccinated people that got a breakthrough case have died.

Okay, but that doesn’t take long Covid into account.

A very fair point. A major concern for everyone, but perhaps parents especially, is the uncertainty surrounding the long-term ramifications of a bout with Covid-19. While it’s easy to shrug off a mild cold, many older patients have experienced fatigue, insomnia, and brain fog months after their diagnosis. Some have estimated as many as 30 percent of Covid patients will have symptoms long after their initial infection; it’s likely that breakthrough cases could have the same problems, though that’s still being studied.

In children, “excess fatigue” and struggles with daily tasks are the primary long Covid symptoms, according to this very helpful explainer from Johns Hopkins.

You mentioned kids. Are hospitals filling up with sick children?

The Delta variant is spreading like wildfire among people who are unvaccinated. That includes kids who aren’t fully vaxxed, of which there are many; people under 12, you may have heard, aren’t eligible for shots yet. Hospitalizations among people 17 and under in the U.S. have recently reached their highest rate of the pandemic, but that number has been low compared to other age groups. And the rise, at least locally, isn’t without precedent. “We have seen an increase in severe pediatric Covid-19 cases in recent weeks compared to earlier this summer, an uptrend similar to the increases we have seen with each regional wave of Covid-19,” says Dr. Danielle M. Zerr of Seattle Children’s. Still: “A higher percentage of the kids being admitted are to the ICU, rather than acute care units, which suggests that the severity of the disease is higher.”

As always, it’s worth stressing that Covid is still primarily a threat to older people. In King County, for every 100,000 people who are nine or younger, there are 27 hospitalizations. For people who are between 10 and 19, that number is 43. For people in their 70s, the rate rises to 927. For 80 and up, it’s 2,080.

A total of three kids have died since Covid-19 arrived in King County; none were under 10.

When will kids under 12 be eligible for shots?

Those between five and 11 years old may be able to get jabs of Pfizer starting sometime in September.

Can vaccinated parents transmit the virus to their unvaccinated, or vaccinated, children?


Are vaccines losing effectiveness over time?

Yes. Though they’re still highly effective at preventing serious illness, they aren’t quite as good at stopping breakthrough cases as they were pre-Delta. That’s a major reason why the White House has decided to offer booster shots to vaccinated people beginning in September. The New York Times cites an epidemiologist saying that new CDC studies “indicate overall that vaccines have an effectiveness of roughly 55 percent against all infections, 80 percent against symptomatic infection, and 90 percent or higher against hospitalization.” Originally, the Moderna and Pfizer vaccines were deemed more than 90 percent effective at preventing infections.

Why has a booster dose of the Johnson and Johnson vaccine not been approved yet?

Researchers are still collecting data on the one-dose program; it received emergency use authorization later than the Moderna and Pfizer shots. It’ll probably end up getting greenlit for a booster.

How can people protect themselves before?

If you’re a moderately to severely immunocompromised person who received a Moderna or Pfizer vaccine, you can go get another shot right now. If you’re not, wait your turn for a booster and mask up indoors. The state also recommends donning a face covering in crowded outdoor spaces while it gathers more information about Delta’s alfresco transmission.

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