With the rising variants of COVID-19 lurking throughout the country again, Dallas County’s progress in reaching herd immunity may diminish. Steve Miff, Ph.D., President and CEO of Parkland Center for Clinical Innovation, explains precisely what herd immunity means.
“The term ‘herd immunity’ describes a situation where a high enough percentage of the population is immune to an infection that the infectious organism can no longer circulate at high enough levels and continue infecting people. The population percentage at which herd immunity is reached changes with the infectiousness of the infecting organism,” he said.
Miff went on to say that after viruses begin to spread, they change, which we’ve seen with such variants as the Delta and Lambda. The Delta variant is changing the herd immunity because it is highly contagious and can be spread by more people through one person.
“By being much more infectious – every COVID infected person can transmit to 5 or 8 people (called the reproductive number and symbolized as R0 5-8) as opposed to the Alpha variant which transmits to 3 to 5 people (R0 3-5), the Delta variant is about 60% more infectious than the original SARS-CoV-2 virus (COVID virus) was. Because of this, we will need to have a much higher bar for immunity.”
The best way to stop these variants from spreading throughout the public is to maintain high vaccination rates. All three vaccines have proven to be a protective barrier in reducing the new COVID-19 variants.
“The most recent research is shedding new light on the number of true protection individuals have, from COVID-19 infection, to include the new strains – like Delta. Being vaccinated with two doses of one of the mRNA vaccines offers the strongest protection. Having only one dose of a vaccine is still protective, but to a lesser degree than having received both shots.”
People who COVID-19 previously infected still need to get a vaccine because they are not fully protected just by having the virus and still have a high chance of getting one of the more robust variants, said Miff.
Miff said herd immunity is not one-dimensional and will ultimately change to follow the path that COVID-19 takes. The best way to continue an upward path is to get vaccinated. However, people still question the safety of vaccines.
As of July 15, 49.2% of Dallas County had at least one dose of the COVID-19 vaccine, with 39.9% being completely vaccinated, he said. The remaining residents need one of the vaccines for the herd immunity that Dallas County has achieved to be maintained.
“Despite the increase in the prevalence of the Delta variant, vaccinations continue to be highly effective. At this point in the pandemic, the key to reaching and maintaining herd immunity is for each of us to receive our vaccinations since vaccines continue to stand up to the virus and be highly effective. That will help mitigate the spread of COVID-19 in all of its variations. The message is simple: don’t wait to get vaccinated. For those still hesitant, the safety and efficacy studies to date are overwhelmingly positive.”
Despite the risk of adverse side effects, the CDC says COVID vaccines are safe to use to prevent COVID-19. Dallas County has a good chance of keeping the population’s immunity if everyone contributes to the effort.
“The key to remaining safe is for each of us to be fully vaccinated and, as appropriate, maintain social distancing, use face covering, continue diligent hand washing and other recommendations of public health authorities such as the Centers for Disease Control (CDC) and the Dallas County Health and Human Services Department.,” said Miff.