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CDC study shows effectiveness of COVID-19 vaccine declines after months

ALABAMA – The Centers for Disease Control and Prevention has released data from a study showing that the effectiveness rate of COVID-19 mRNA vaccines has declined over several months.

The study focused on adults who were tested for COVID-19 who were hospitalized or visited emergency rooms and urgent care. It looked at data from 10 hospitals from August 2021 to January 2022.

Vaccine efficacy rates were higher during the delta wave than during the omicron surge. In both periods, vaccine effectiveness was higher for people who received a booster dose.

Overall, in emergency rooms and urgent care, mRNA vaccine efficacy was 92% for those who received two doses of an mRNA vaccine and their booster less than 2 months previously . It decreased to 75 percent after 4 months.

Regarding hospitalizations, vaccine effectiveness for patients receiving a booster within two months of admission was 95%. It decreased to 81 percent after 4 months.

Dr. Wes Stubblefield of the Alabama Department of Public Health says the CDC has recommended booster shots to combat a drop in COVID antibody levels. He says the results are not surprising.

In Alabama, where the vaccination rate isn’t as high as in other states, Stubblefield says the vaccine becomes less effective over time, raising some concerns.

“When the effectiveness of the vaccine goes down and a substantial part of the population is not vaccinated, then you have more pool of infectivity there, so that if something happened, another variant, something more serious, potentially more people could be infected, and potentially with poor outcomes,” Dr Stubblefield said.

Stubblefield can’t say if there will be a recommendation for more doses in the future, but he had this to say about the verbiage surrounding a person’s vaccination status…

“We are trying to change our strategy from talking about being vaccinated to fully vaccinated to being up to date. And being up to date means you got everything you could get for your age and situation. And these are different,” Stubblefield explained.

He also stresses the importance of being vaccinated, pointing to data that shows vaccinated people tend to suffer from less severe disease.

On February 11, the CDC updated some of its guidelines for booster shots for people who are moderately or severely immunocompromised, including shortening the time between completing the mRNA vaccine series and receiving the booster injection.


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