The team's paper, which was posted Aug. 7 on medRxiv, looked at more than 14,000 blood samples from 10,482 Texans. These samples were obtained throughout the state beginning Sept. 30, 2020. Estimates done by the UT System researchers found that 35.3 percent of Texans possessed natural antibodies, amounting to a total immunity of 69.1 percent.
The UT System researchers who penned the study put forward three assumptions. First, they assumed reinfection with COVID-19 within a few months is rare. Second, neutralizing antibodies following a bout of natural infection typically lasted for at least five months. Third, COVID-19 vaccines produced "a robust and reasonably long-term antibody response."
"This means 70 percent of the population benefit from some degree of protection from reinfection from SARS-CoV-2 and acquiring COVID-19," the study authors wrote. They continued: "We conclude the seroprevalence of SARS-CoV-2 is four times higher than the state-confirmed COVID-19 case [at 8.8 percent.] Seroprevalence referred to the percentage of people in a certain population who have antibodies to a particular virus.
The researchers defended the methodology they used for the study. "In contrast to model-based approaches, the current research will allow researchers and health departments to calculate regional estimates of total immunity in the least biased manner," they wrote. The study authors further added that the model they used may be replicated in any state or regional area to help policymakers when it comes to public health decisions.
Herd immunity is impossible with the vaccine-driven delta variant
Herd immunity happens when enough people in a certain population become immune through a disease. This can be achieved through either natural infection or mass vaccination. When a population achieves herd immunity, pathogens will have a less chance to spread and those who are not immune will be protected likewise.
Initially, the percentage for herd immunity was pegged at 70 percent. This was later increased to 85 percent, then 90 percent. But now, a number of experts have claimed that herd immunity is impossible due to breakthrough infections caused by the more transmissible B16172 delta variant. Three British medical experts expressed their thoughts on the matter. (Related: TRICKSTER: Fauci moves goal posts AGAIN, now says 90% vaccination is necessary to reach covid "herd immunity".)
Dr. Andrew Pollard of the University of Oxford was one of the medical experts that put forward the claim. According to him, vaccines did little to stop SARS-CoV-2 transmission as evidenced by the fact that vaccinated people still caught COVID-19. "I think we are in a situation here with this current [delta] variant, where herd immunity is not a possibility because it still infects individuals," he said.
Pollard also warned of the possible emergence of new, more transmissible variants that circulate among vaccinated individuals. He said: "I suspect that what the virus will throw up next is a variant [that] is perhaps even better at transmitting among the vaccinated populations. [That's] even more of a reason not to be making a vaccine program around herd immunity." (Related: Scientists: Mass vaccinations will not stop COVID-19 transmission, herd immunity not achievable.)
Dr. Andrew Freedman of Cardiff University School of Medicine agreed with Pollard's assessment that herd immunity was unlikely. "The delta variant is highly transmissible, meaning the proportion of people needing to be fully vaccinated for herd immunity is probably not achievable," he told CNBC. Freedman also noted that while the COVID-19 vaccines worked against severe disease, hospitalization and death, they are "less effective in preventing infection, mild disease and [viral] transmission" from infections caused by the delta variant.
Imperial College London professor Danny Altmann also told CNBC that he agreed with Pollard's view. He explained that the herd immunity mathematical model could not easily be applied to an "unprecedented" virus such as SARS-CoV-2. According to Altmann, the virus responsible for COVID-19 is "still little understood" – given that new variants of it are emerging and circulating around the globe.
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