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Catherine Troisi

We’re (sort of) halfway vaccinated

It depends on how you’re measuring it. And it’s still not enough, no matter how you look at it.

Texas has hit the halfway point.

As of Friday morning, 50.1 percent of Texans 18 and older are fully vaccinated from COVID-19, according to the Centers for Disease Control and Prevention.

While this is a milestone for the state, Dr. Susan McLellan is not celebrating.

“It means that 50 percent are not vaccinated, and that’s a problem,” said McLellan, professor of infectious diseases at University of Texas Medical Branch. “It’s been available for everybody 12-and-older for months. I don’t think that’s a very wonderful milestone.”

McLellan and other Texas doctors are concerned about the coronavirus case rate and the country’s newly-introduced, highly-transmissible delta variant. Now the dominant COVID strain in the U.K., experts expect the delta variant to become the dominant strain in Texas, as well.

Early studies show vaccination provides better immunity than contracting the virus does, McLellan said.

“Right now, there are pockets in the population that are not getting vaccinated, and they tend to congregate,” she said. “Young adults may think it’s no biggie to not get vaccinated, and then they go to a bar with a lot of people like them. They easily expose each other and spread it around.”

State vaccination rates can be misleading as a large percentage of vaccinated people live in large urban centers, such as Houston, Austin and Dallas, said Dr. David Lakey, a member of the Texas COVID-19 Expert Vaccine Allocation Panel.

In Harris County, more than 1.8 million people are now fully vaccinated, followed by Dallas County at 1 million. In Travis County, more than 631,000 people are fully vaccinated, the DSHS reported Friday.

[…]

Texas ranks 33rd among all states for its rate of vaccination. And its proximity to states with low vaccination rates — including Louisiana, Mississippi and Alabama — could pose a threat to Texans, said Dr. Catherine Troisi, an epidemiologist with UTHealth School of Public Health.

“We don’t live in a bubble,” Troisi said. “People travel from state to state, and they can bring the infection with them.”

This story measured the vaccination rate for people 18 and older. Of course, kids are still vulnerable to COVID, and you can get vaccinated if you’re at least 12 years old, so that’s a somewhat odd way of measuring progress. The Trib identifies 40% of the state’s total population as being vaccinated, with Harris County continuing to be right at the same level as the state as a whole. They give totals for “people who are fully vaccinated”, which will include people who have had two Pfizer or Moderna shots plus people who got the one-shot J&J vaccine, and “total number of shots administered”, which includes people who have had just their first Moderna or Pfizer shot. I estimate from this that Harris is close to fifty percent of the total population having at least one shot, again consistent with the statewide number.

So that’s good and the number will continue to rise, but much more slowly since basically everyone who was eager to get a shot has had theirs. We’re fully into the “people who are hesitant” and “people who face obstacles” part of the journey, and that’s just going to take longer. In the meantime, the Delta and other variants are surging in the parts of the country (and elsewhere) that are less vaccinated, and while hospitalizations remain at manageable levels, that could change. A lot of the country, and a lot of Texas, remains at high risk because of low vaccination rates. I don’t know what more we can do about that.

Please get your second shot

I hope this is mostly a function of incomplete data.

Millions of Americans — including tens of thousands of Houstonians — either have delayed or are forgoing their second dose of a COVID-19 vaccination.

As of late last month, roughly 51,000 people who received their first inoculation through the Houston Health Department were “overdue” for their second dose. The department’s number is preliminary but includes any person who has gone at least 42 days since their first round without returning for a second shot.

Statewide, more than 630,000 of the roughly 11 million people who’ve received one dose are more than six weeks overdue, the Texas Department of State Health Services told the Houston Chronicle.

“We need a lot of those folks from February to come back in and get their second dose now,” Dr. David Lakey, a DSHS commissioner who sits on Texas’ COVID-19 Expert Vaccine Allocation Panel, said last week.

Part of the gap, however, is likely due to people who opted to receive their second dose through other health care providers as vaccine availability expanded.

It’s not cause for alarm just yet, said Rice University health economist Vivian Ho, though she said the trend does not bode well for the overall goal of herd immunity.

[…]

Ho said people shouldn’t be dissuaded from rescheduling appointments that they missed, as they’ve been shown to give additional antibodies even if they come late.

“The first dose really does boost your antibodies, but it’s the second that really gives you the second umph,” she said.

Houston Methodist radiologist Dirk Stotsman worried that some people are forgoing their second round of inoculations because the first doses of Moderna and Pfizer have been proven highly efficacious against the virus.

While the first dose offers a good level of protection, he said, the extra antibodies provided by the second dose will be integral to prevent the spread of more infectious and dangerous strains of the virus.

Getting just the one Pfizer or Moderna shot is better than nothing, but it’s not as good as it should be. If you’ve gotten one shot and for whatever the reason not gotten the second one, it’s not too late. Go ahead and make an appointment or do a walk-in where available.

In related news:

With the rescission of the mask mandate and full reopening of businesses, medical experts worried spring would bring a debilitating fourth wave of COVID-19 infections to Texas.

But as vaccination rates slowly leveled off in recent weeks, the rate of infections and hospitalizations did as well. More than a year after businesses closed, offices sent workers home and traffic vanished from Houston’s concrete jungle of freeways, public health officials are cautiously optimistic efforts to quell the spread of the virus and vaccinate as many people as possible are working.

Yet despite claims from officials like Gov. Greg Abbott that this downturn is linked to “herd immunity” — the mysterious target ranging between 60 and 80 percent fully vaccinated against COVID-19 — experts say Texas cannot rely on vaccinations alone to achieve what some think may mean the end of the pandemic.

“Nobody knows for sure what’s going to happen,” said Catherine Troisi, an infectious disease epidemiologist with UTHealth School of Public Health in Houston. “But my educated guess would be as more of the population becomes either vaccinated or immune through natural infection, we won’t see as many cases.”

Fewer than 3,000 patients have been hospitalized across the state for the past five weeks, according to a Chronicle data analysis. It’s the longest streak with that few patients since June 2020.

Dr. Carl Vartian, chief medical officer at HCA Houston Healthcare’s Clear Lake and Mainland hospitals, worries the public conflates “herd immunity” with “ending COVID-19.” But COVID-19 may not truly end. Rather, experts suspect it will become “endemic,” never fully leaving the population — like influenza, which still infects hundreds of thousands of people a year in the U.S.

Again, what we have now is better than what we had before, but not as good as it could be. Even at “herd immunity levels”, there’s still a lot of unvaxxed people. The difference is that it becomes harder for the virus to really take off as it has done before. But people can and will still get sick and die if they’re not vaccinated. It’s up to us what the level of those illnesses and deaths are.

We are not ready to re-reopen

I don’t know who needs to hear this, but…

Texas COVID-19 hospitalizations have declined the most significantly — 4,144 Tuesday, down from 10,893 on July 22 — but new cases, positive test rates, daily deaths and viral spread are all dropping. They are dropping enough that one Texas modeler, Spencer Fox of University of Texas at Austin, went so far as to say he thinks that Texas may have seen the worst of the pandemic — as long as people continue to wear masks and keep their guard up.

A number of other health experts warned against lifting restrictions, noting that the coming Labor Day weekend, the expected resumption of schools and seasonal weather changes have the potential to cause a resurgence like Texas experienced earlier in the summer. They also said the amount of transmission, although improved, is still way too high.

“I don’t want to be Debbie Downer, but we’ve been surprised before,” Catherine Troisi, an infectious disease epidemiologist at the UTHealth School of Public Health, said last Friday. “It’s a double-edged sword when things start looking better. The virus is still out there, but people think things can go back to normal.”

Troisi added that some experts are hesitant because of the state’s data reporting problems, because it’s possible some other issue will surface. Those problems include under testing, coding errors that caused backlogged results and combining positive diagnostic and antibody tests.

Chris Amos, a Baylor College of Medicine quantitative scientist, said “the timing could not be worse for rolling back.”

“Given the number who test positive reflect perhaps 10 times as many individuals who have not been tested but are positive,” said Amos, “there remains a large pool of individuals who can spread COVID-19 if they begin interacting with many others, and particularly if we allow large groups to start coming together again.”

Amos acknowledged that optimism about opening up is natural given the slowing of COVID-19’s spread. The spread is measured by a value, known as reproductivity, that suggests a slowing or growing of the virus. Over 1 means each infected person transmits it to an average of more than one person and the epidemic grows; under 1 means the virus is transmitted to less than one person and the epidemic won’t sustain itself.

The value for the state overall has been under 1 since July 20.

According to Amos’ calculations, if the state maintains the current trend, with the number around 0.87, it would take 38 days to reduce the COVID-19 burden by another 50 percent.

It’s important to keep reducing that burden before students resume in-person classes, Amos said. He and others advised against a one-size-fits-all approach.

“Not every community or county in Texas is experiencing the same burden of disease,” said Angela Clendenin, an epidemiologist with the Texas A&M School of Public Health. “In some places, it may be justified to roll back some restrictions whereas in others, it’d be ill-advised to do so. It will be critically important that rolling back restrictions does not send the message that we are somehow ‘all clear.’”

See here for the background. The basic fact remains that we are still at levels well above where we were in early June, when we first re-opened. There’s no question that if we re-reopened like we re-opened the first time around, we will get the same result. To me, three things are clear. One we shouldn’t change anything until we are back at early-June levels. Two, we should have sensible objective metrics that we can actually measure with accuracy and that we stick to, unlike the first time around. And three, give some discretion back to local jurisdictions so that the counties with a sufficiently low infection rate can be more open (though still within state guidelines) while those that aren’t ready for that kind of openness can continue to do what they need to do to get there. All of this should be screamingly obvious after what we just went through, but I see no reason to believe that Greg Abbott or Dan Patrick have learned anything from that experience.

Who needs testing?

It’s the surest way to see the infection rate decline, am I right?

The number of Texans being tested for the coronavirus has fallen sharply in recent weeks, a trend that has worried public health experts as officials consider sending children back to school while thousands more Texans are infected each day.

In the week ending Aug. 8, an average 36,255 coronavirus tests were administered in Texas each day — a drop of about 42% from two weeks earlier, when the average number of daily tests was 62,516.

At the same time, the percentage of tests yielding positive results has climbed, up to 20% on average in the week ending Aug. 8. Two weeks earlier, the average positivity rate was around 14%.

On Saturday, the state set a record for its positivity rate, with more than half of that day’s roughly 14,000 viral tests indicating an infection.

Taken together, the low number of tests and the large percentage of positive results suggest inadequacies in the state’s public health surveillance effort at a time when school reopenings are certain to increase viral spread, health experts said.

“Opening the schools is a really complicated problem, and the best thing we can do is get the number of cases down so kids can go back to school safely,” said Catherine Troisi, an infectious disease epidemiologist at UTHealth School of Public Health in Houston. “There are so many reasons why kids need to be in school, particularly younger kids, but we’re finding out more and more they can get infected, and the concern is them bringing it home and spreading in the community and spreading to teachers.

“I think the worst thing would be for schools to open, then close,” she said. “That really makes it hard on parents, that unpredictability, and there’s a lot of costs associated with opening the schools safely.”

[…]

The number of tests performed in Texas has “never been great,” said Vivian Ho, a health economist at Rice University and Baylor College of Medicine, but “it’s extremely troubling” that the numbers have dipped since last month.

“It’s troubling because we can guess at some of the reasons, but we’re not sure,” she said.

She suggested that some people may have been discouraged by long wait times for test results, or less concerned about the virus’ toll in Texas after a frightening peak in July began to flatten out.

A declining number of tests is a particularly thorny issue for schools, Ho said. “No public school has the resources to do testing under the current circumstances. There are huge class sizes and crowded hallways,” she said.

Does any of that sound good to you? Because none of it sounds good to me. Again I say, remember when Greg Abbott’s plans for reopening included sufficient testing capacity and a positivity rate under ten percent? Boy, those were the days. Oh, and as the story notes, the TEA still hasn’t yet released any specifics on which districts will be able to receive waivers to limit in-person instruction beyond eight weeks or under what circumstances. So, you know, the school situation remains a mess. Isn’t this fun?