Several weeks ago, most of the Houston area’s COVID-19 metrics were trending in the right direction. According to the Texas Medical Center, the spread of the coronavirus was slowing down, not speeding up, and that combined with low daily new case counts and falling hospitalizations put the region temporarily in the realm of “community control.” Things were getting better.

Still, local health experts were concerned that the arrival of the highly contagious Delta variant of the disease coupled with the Fourth of July holiday weekend could be the source of another spike in local cases, as folks gathered with loved ones to grill and watch fireworks in a community with a still disconcertingly high amount of people who’ve chosen not to get vaccinated against COVID-19 out there.

Unfortunately those fears were justified according to Dr. Maria Rivera of Harris County Public Health.

“Over the last couple of weeks — and especially over the last week, and even this weekend specifically — we have seen a pretty significant increase in the number of cases in Harris County,” Rivera said, “as well as in the test positivity rate, and a less dramatic increase in the number of hospitalizations due to COVID-19, both in the general beds and in the ICU.”

“It’s not entirely surprising that now, almost exactly two weeks after the Fourth of July weekend, we’re now seeing these surges and increases,” Rivera said, given that public health experts tend to expect coronavirus spikes related to changes in people’s behavior to take a couple of weeks to show up in the data.

“We are concerned that this is a true surge. It seems to be heading in that direction,” Rivera warned. “What we don’t know is how high it’s going to go, how many cases we’re going to see, how many hospitalizations we’re going to see, but it’s definitely concerning that cases are increasing so rapidly. And so we’re treating it as a new surge.”

Perhaps most troubling is the change in the Houston area’s reproduction rate, as measured by the Texas Medical Center. For multiple weeks in late June and early July, the reproduction rate was below 1.0, meaning that coronavirus’ spread was slowing down. But for the past two weeks, the Houston area’s reproduction rate has ramped up significantly, hitting 1.58 two weeks ago and 1.33 last week.

The local test positivity rate has been trending up steadily across Harris County for the past two weeks now. Statewide, the number of COVID-19 tests coming back positive is the highest it’s been in months — Texas’ seven-day average positivity rate now sits at 10.08 percent, the first time it’s hit double-digits since late February after previously hitting a pandemic-low of 2.26 percent in the middle of June of this year.

The U.S. Centers of Disease Control and Prevention’s Director Dr. Rochelle Walensky said Friday that “This is becoming a pandemic of the unvaccinated” in the United States, given that the overwhelming percentage of new positive cases and hospitalizations are showing up among those who have so far refused the potentially life-saving shots from Pfizer, Moderna and Johnson & Johnson. That trend has held true in Harris County as well, Rivera said.

But several breakthrough infections over the weekend among five of the Texas House Democrats who flew to Washington, D.C. to halt the state Legislature’s special session have become the latest high-profile examples that even the vaccinated aren’t wholly safe from the coronavirus, even though they’re virtually guaranteed not to suffer severe symptoms or to be killed by the disease.

In response to a healthy bit of mockery directed toward the absentee Democrats from Republicans and other contrarian critics given that multiple photos of the maskless state Democrats in close quarters on one of the private planes that took them to D.C., State Rep. Gene Wu (D-Houston) admitted Monday that he and his fully-vaccinated colleagues “got complacent because we felt safe.”

Let our mistake be the object lesson.

All of us had been fully vaccinated since March. We got complacent because we felt safe. We had no positives for months, and we got sloppy.

Being vaccinated doesn't ALWAYS stop you from spreading the virus.

ALWAYS MASK UP INDOORS! pic.twitter.com/aeCPxvacxD

— Gene Wu (@GeneforTexas) July 19, 2021

He said that even given the CDC’s guidance that people who are fully vaccinated can do away with masks in virtually all settings, the weekend’s rash of infections among his colleagues was proof that “Being vaccinated doesn’t ALWAYS stop you from spreading the virus,” and signaled that he’d be keeping his mask on indoors for the foreseeable future.

In an interview with Yale Medicine's blog, the medical school’s Dr. F. Perry Wilson explained how the Delta variant spreading across Houston and the globe is particularly concerning given how much more quickly it can be transmitted compared to both the original form of COVID-19 and its previously most well-known variant, Alpha, which used to be called “the U.K. variant.” According to Wilson, the Alpha variant was 50 percent more contagious than the original strain of COVID-19, and Delta is 50 percent more contagious than Alpha.

Rivera said the high-profile positive cases among the vaccinated Texas Democrats wasn’t surprising given the stubbornly high number of people who still refuse to get vaccinated combined with Delta’s high transmission rate. There were always going to be breakthrough cases considering that even the most effective vaccines are only approximately 95 percent effective in preventing transmission, Rivera said, and explained that Delta’s rapid spread among the unvaccinated will mean more vaccinated people will end up getting COVID-19 than they would have otherwise.

That said, the county’s guidance that fully-vaccinated residents can go about their normal lives mask-free except when required by law (like when using public transportation or flying on airplanes) isn’t going to change based on a few notable breakthrough infections, Rivera told the Houston Press.

“From our point of view, the guidance stays the same,” Rivera said.

“What we know is what we already knew: that no vaccine is 100 percent effective. And as cases start to increase in the community, the number of breakthrough cases by default is going to increase as well,” she said.

The key thing Rivera is worried about is the decline in how quickly Harris County residents are getting vaccinated. “Late spring, we peaked, and since then it's started to decrease, and over the last couple of weeks has really plateaued,” Rivera said. There was a small uptick when some vaccines were authorized for use in 12 to 15-year-olds, but that’s since leveled off as well, she said.

Rivera stressed that vaccines are still free and widely available across the county, and that vaccine demand has fallen so significantly that people can just walk up to most county clinics for a shot without having to make an appointment ahead of time.

“We’ve only vaccinated around 50 percent of Harris County residents,” River said, “and around 60-ish percent of people that are eligible, but it’s still not at high enough rates as we would like.”

While all of the currently available vaccines still offer strong protection against severe sickness, hospitalization and death from the coronavirus — even the Delta variant — Rivera said that the more people out there who don’t get vaccinated, the greater number of opportunities there will be for COVID-19 to continue to mutate.

Each infection provides an opportunity for the virus to evolve, Rivera explained, and it’s definitely within the realm of possibility that a mutation could arrive someday that proves too much for the vaccines to handle.

“It’s not something that we’ve seen yet, and it’s something that I hope we don’t see,” Rivera said, “but if we don’t continue to get a larger percentage of the population vaccinated, then that is a possibility that there could be a variant where the vaccines are no longer effective.”