Researchers find vaccines have helped in Missouri

Annika Merrilees
St. Louis Post-Dispatch

ST. LOUIS — A data analysis by St. Louis University researchers shows just how much COVID-19 vaccines have prevented infections: The researchers found that, on average, for each additional percent of a county's population that received a first dose of vaccine, there were four fewer weekly infections.

The data was released Monday on the website medRxiv, where researchers post study results of urgent interest, prior to peer review.

Enbal Shacham, a professor at St. Louis University's College for Public Health and Social Justice, and the lead author, said the analysis has been submitted to an academic journal to be considered for publication.

Shacham said that, while the three COVID-19 vaccine products available in the U.S. have been shown to dramatically reduce infections, the researchers wanted to study the actual relationship between a community's vaccination rates and its case rates.

"I think everyone wants to know, if I do something, like get a COVID vaccine, are there actually less cases in my county?" Shacham said. "And, yes. That's true."

The researchers looked at all of the counties and two cities in Missouri over a 25-week period from Jan. 4 to June 26. They used data from the Missouri Department of Health and Senior Services.

One of the most significant findings, Shacham said, was that, even in counties with relatively lower vaccination rates, the vaccines still helped. Those counties did not have to reach a certain threshold of vaccinations before they began to see a benefit.

The data, the authors wrote, suggest that "each person getting vaccinated has an impact."

Shacham said that the analysis did not account for other public health measures, like face mask requirements.

Missouri has seen increasing COVID-19 infections since early June, and health officials have tried to spur vaccinations in order to prevent further spread. The state's seven-day average of new confirmed cases has doubled in less than four weeks, to 706 on Tuesday, from 342 on June 12, according to a Post-Dispatch analysis.

Statewide, 2.7 million people, or about 44.8% of the population have received at least one dose. And of those, 2.4 million people, or 39.3% of the population, are fully vaccinated, according to the state.

The Centers for Disease Control and Prevention said Tuesday 55% of the U.S. is partially vaccinated and 47.5% is fully vaccinated.