When could we reach herd immunity?

HOUSTON, Texas (KTRK) -- On day one of the Lone Star State removing all COVID-19 restrictions, hospital leadership in the Texas Medical Center answered questions on a number of topics related to the coronavirus.

Four leaders in the Texas Medical Center and health field participated in the nearly one-hour discussion.

  • Bill McKeon, President & CEO, Texas Medical Center
  • Paul Klotman, MD, FACP, President, CEO and Executive Dean, Baylor College of Medicine
  • David Persse, MD, Chief Medical Officer, Houston Health Department
  • Esmaeil Porsa, MD, MBA, MPH, CCHP, President & CEO, Harris Health System


During the talk, McKeon said that within the last month, we've gone from 90,000 vaccinations a week to over 232,000, explaining that while at first vaccinations were limited to hospitals and health care workers, we've seen growth in the vaccinations because of pharmacies being able to distribute it and give people more access.

While the entire briefing is worth a watch as our state and country continue to fight our way out of this pandemic, we have listed four key takeaways. Remember that you can watch the entire discussion in full in the video player above, or if you prefer to see it on a bigger screen, switch over to the free ABC13 streaming apps for Roku, Fire TV, Android TV and Apple TV.

How did the winter storm affect the vaccine rollout and rate?



Dr. Persse pointed out that the ice storm that hit in mid-February shut down vaccination programs for days, creating challenges in getting people rescheduled for their appointments. But that struggle wasn't limited to the city of Houston. It affected any community providing the vaccine.

"Across the community, it probably set us back thousands of doses per day, at least two or three days of vaccinations weren't done," Dr. Persse said. "But we're catching up."

The winter weather also caused the area to shut down testing sites.

"We've also seen a lot fewer people going to get tested, so I'd like to reinforce to folks it's still important that people go ahead and tested. Certainly if you haven't been vaccinated. But even for folks who have been vaccinated, remember, these vaccines are not 100% protective, so certainly if you have been vaccinated, you develop symptoms, you really need to go get tested," Persse said.

Persse said that even though he has been vaccinated, he still gets tested because he doesn't want to spread COVID-19 to family members and there's greater risk of developing mild illness, if infected.

If I've already had COVID-19, do I still need to be vaccinated?



In short, yes.

But Dr. Klotman with Baylor College of Medicine also gives this much more scientific answer:

"The natural infection with this virus leads to your body developing antibodies to all parts of the virus," Dr. Klotman said. "There's the envelope, the surface of the virus. There's the protein that attaches to the cell, and that protein is in three or four different conformations. Some of them are not important. Others are really important."

Dr. Klotman said some of the antibodies are very effective at stopping infection, which is what helps you to recover from the virus, and then your natural immunity wanes over time.

It's not clear how long natural immunity lasts.

"The point is, when you get a vaccine that is directed only to the spike protein and only to the conformation of that protein that attaches to the receptor, you get a ton of antibodies generated just to the most important part of the virus," Dr. Klotman continued. "So even if you've been infected, yeah, you have a low level. It's enough to prevent you from getting really sick, you recovered, but it may not prevent you from carrying the virus."

The bottom line?

"Even if you've had the disease and gotten over it, we recommend that you get vaccinated because it's a much more targeted antibody response," Dr. Klotman said.

Why is the vaccine race against the different COVID-19 variants so important?



Simply put, the variants are more infectious.

"The major issue is it's spreading faster, so our race is to get you vaccinated and reduce the spread around the community," Dr. Klotman said. "We know that morbidity and mortality is really based on the number of infections, so the more people are infected, the more problems it's going to be, the more hospitalizations it's going to be and the more death there's going to be."

But there is a positive.

Dr. Klotman said it seems that all of the vaccines are effective against the variants, including the Brazilian variant.

Dr. Persse summed it up like this.

"The sooner we can get the pandemic under control, not only nationally but globally, the less likely we'll have a mutation that actually does get around the vaccine," he said. "Right now, the vaccines we have are highly effective. We need to use them now. Put this dragon back in its bottle before it figures out a way to get us around us."

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When could we reach herd immunity?



Dr. Klotman explains that herd immunity is not a made-up number. It's a calculated amount based on how infectious the virus is.

With the original strain, he says, you needed 60-65% vaccinated to reach herd immunity. But with the new variants, that number could go up to 75%.

Still, Dr. Klotman estimates that we could hit that 65%, in conjunction with following public health measures, by mid-July or mid-summer.

"If you look at the fact that probably close to a 1/3 of the population of the United States has probably been infected already... if we could get to 50% of the population vaccinated, the combination of vaccinated and people who have been infected, we would be ok by July," Dr. Klotman said.

He warned that if public health measures stop, we'll get to herd immunity faster but for a grim reason: a lot more people would be infected and could die in the interim.

Among the other topics discussed were:

  • the recent authorization of the Johnson & Johnson vaccine
  • the efficacy and science of the three vaccines
  • the latest COVID-19 data trends


Effective at 12:01 a.m. Wednesday, Texas' mask mandate lifted and all businesses were allowed to open at 100% capacity.

The doctors touched on the lifting of the mask order, saying they were concerned, but especially about spring break and the possibility of a surge that could affect hospitals with a large number of infections.

"I want everybody to remember the virus is the enemy. Mask wearing is a strategy, a very effective strategy to minimize the spread of virus," Dr. Persse said. "Let's try to get away from the politicization of it. The point is, this virus doesn't care about any of that. This virus is an opportunistic entity. If you give it an opportunity, it'll take it."

While the work isn't over yet to stamp out this pandemic, the medical professionals praised the efforts to have mass COVID-19 vaccination sites.

Just this week it was announced Rice Stadium would serve as a site starting March 15.

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