It Could Take Another Year Until Missouri Reaches Herd Immunity
Even if the federal government boosts vaccine supply and every U.S. adult becomes eligible in May, widespread immunity could still take until 2022.
Missouri has vaccinated 20% of the state’s population and expects a significant jump in the vaccine supply by summer — enough for all adults in the state to obtain a COVID-19 shot.
But even if the federal government boosts vaccine supply so that all U.S. adults could sign up for an appointment slot by May, as President Joe Biden promises, the state is still a year away from reaching widespread immunity, estimates Enbal Shacham, a public health professor at St. Louis University.
That’s because a vaccine has not yet been approved for children.
“Ultimately, what we need to be able to identify is that the vaccines work as well for children, and they don't have any side effects that are concerning,” said Shacham, who studies infectious disease modeling.
People under 18 years old made up nearly a quarter of the U.S. population in the 2010 census. Without a vaccine available to children, it’s unlikely the U.S. will reach herd immunity, Shacham said.
Missouri Gov. Mike Parson announced Thursday that their states will expand vaccine eligibility to every adult by mid-April.
Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, and other health officials estimate up to 85% of the population needs to receive a vaccination or have had COVID-19 to stop the disease from spreading.
“We don't know the exact number,” Shacham said. “We know that the more is better. And we're urgently racing against strains and more infections.”
Pharmaceutical companies plan to conduct studies over the next year to make sure vaccines are safe for kids, Shacham said. Moderna administered its first shots to children 6 months to 11 years old on Tuesday. Pfizer is studying the effectiveness of its vaccine in 12- to 15-year-olds.
In the meantime, Shacham said it’s important to inoculate as many adults as possible. That could help determine if vaccinated individuals can spread the virus to others. Shacham said parents will be essential to determining if they can spread the virus to their unvaccinated children.
“That's one of the biggest frustrations is that we don't have the exact number that we have to aim for,” she said. “We're really good at getting to a deadline or getting to a number that we have to hit.
"But this pandemic has shown us that we have to be far more patient than we want to be.”
Officials in the St. Louis region have criticized Missouri Gov. Mike Parson’s administration for not placing enough vaccination sites in St. Louis and Kansas City, prompting many residents to hunt for vaccine doses in rural parts of the state. Last week, Missouri officials announced plans to switch distribution models from allocating based on population to assigning doses based on need. That change will go into effect within two weeks.
Shacham said the state should be focusing on vaccinating denser populations to speed up herd immunity.
This summer could be pivotal for the vaccine rollout because supply is expected to catch up with demand. But the St. Louis region will only achieve herd immunity if vaccinations cover the area of people who travel into the city for work and play.
“The boundaries that we draw out don't mean anything for the humans that live there. Whether it's ZIP code, county or state, we don't function in those roles,” Shacham said. “So Missouri, reaching herd immunity is also dependent on all the states that border it.”
In the four months since the Food and Drug Administration approved the first vaccines, more than 73 million Americans have received at least one dose, according to the Centers for Disease Control and Prevention.
A consistent vaccination rollout depends on multiple variables, including keeping infection rates low and gauging how many people are truly hesitant to get a shot, Shacham said.
Experts say they can more accurately estimate the number of people who are vaccine hesitant when long waiting lists dwindle and doses become more accessible. Conservative residents in rural areas of the state are more likely to refuse the vaccine, according to a January survey from the Missouri Hospital Association.
People who were initially skeptical about the shot are now getting vaccinated because it’s becoming a social norm, said Mary Politi, a public health professor at Washington University.
“I think that people are starting to see more and more of their neighbors, their friends or colleagues, their health care providers talking about the safety and importance of vaccines,” she said.
Until the nation reaches herd immunity, Shacham, the SLU professor, said it’s important to keep wearing masks and washing hands frequently.
“We want to be done with COVID. But COVID isn't done with us yet,” she said.
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