ST. LOUIS — It's become part of our new pandemic vocabulary, but what exactly is "herd immunity?"
Defined by the CDC as “when a high percentage of the community is immune to a disease (through vaccination and/or prior illness), making the spread of this disease from person to person unlikely,” it's essentially when enough people have protection against a virus or disease that it no longer wreaks havoc on the population.
Health experts warned since COVID-19 is so deadly to so many, the protection of a vaccine is critical.
In the St. Louis area, the Metropolitan Pandemic Task Force is targeting 75% of the adult population being vaccinated as having achieved herd immunity. They estimate if we maintain the current rate of 77,000 first doses per week, we should reach herd immunity by the week of June 20.
“Of course if you increase your vaccination rate then that date shifts to the left, and so, then we get there even faster,” said Dr. Alex Garza, head of the task force.
And that could happen, with expanding eligibility and many more large vaccination events planned.
While Dr. Garza said they do factor in people who’ve gotten COVID-19 or have been exposed to it in determining how immune the population is overall, it's proven tricky to really understand a survivor’s level of immunity. Vaccination rates are hard data, which is why it's the foundation for their projections.
“That's a true marker of, 'Yes we've established immunity,'” he said.
Soon the challenge could be making sure 75% of the adult population wants the vaccine, which Dr. Garza said underscores the importance of reaching out to populations and communities that might have higher levels of hesitancy.
He also said it is important not to reduce mitigation strategies like handwashing, mask-wearing, avoiding large groups and travel, and social distancing to ensure the timeline isn’t impacted by a surge in COVID-19 cases.
“Do not tempt the pandemic gods, that's all I’ve got to say.”