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Updated COVID-19 vaccines have high effectiveness

Last updated on March 10th, 2024 at 02:07 pm

Recently published research provides firm evidence that the updated COVID-19 vaccines have high vaccine effectiveness in preventing serious outcomes such as emergency department visits and hospitalization. This is more data supporting the effectiveness of the COVID-19 vaccines compared to not vaccinating against the disease.

I think that there is a myth that COVID vaccines are not effective in preventing a COVID infection, but the data hasn’t supported these types of claims. This study shows that COVID vaccines are indeed very effective in keeping the vaccinated person from developing the most serious outcomes of COVID-19.

As I usually do, I’ll guide you through the key results and then give an analysis of the new study.

vaccine bottles on blue background
Photo by Maksim Goncharenok on

COVID-19 vaccines effectiveness against serious outcomes paper

In a paper published on 29 February 2023 in the CDC’s Morbidity and Mortality Weekly Report, researchers examined data from 369 emergency departments and urgent care clinics and 229 hospitals across eight states in VISION (Virtual SARS-CoV-2, Influenza, and Other Respiratory Viruses Network), along with 26 hospitals in 20 states in the IVY (Investigating Respiratory Viruses in the Acutely Ill) network.

The researchers analyzed emergency department and urgent care visits included 128,825 adults (median age 52 years, 61% female, 64% white) who visited facilities within VISION for COVID-like illness, including 17,229 case patients (those who received a positive SARS-CoV-2 test) and 111,596 controls (those who received a negative SARS-CoV-2 test). Approximately 8% of the case patients and 12% of controls had received the 2023-2024 COVID vaccine dose. This is, by any definition, a large cohort study (which rates high on the hierarchy of medical research).

Here are the key results from the study:

  • COVID-19 vaccine effectiveness (VE) against emergency department and urgent care visits was slightly higher for those who had received the vaccine 7-59 days before the visit compared to those who received the vaccine 60-119 days earlier, 50% vs 45%, respectively. This means that those who received the updated COVID vaccine had a 50% or 45% lower risk of requiring an emergency room or urgent care visit than those who had NOT received the vaccine.
  • VE against emergency department and urgent care visits was higher for adults ages 18-64 years old than for adults ages 65 years and older, 50% vs 45%, respectively.
  • VE against COVID-related hospitalizations was higher in the first 7-59 days after vaccination compared to 60-119 days after vaccination, 53% vs 50%, respectively.
  • VE against COVID-related hospitalizations was higher among patients 65 and older compared with adults under 65 years, 53% vs 43%, respectively.

The researchers concluded:

…updated COVID-19 vaccine dose provided increased protection against COVID-19–associated emergency department and urgent care encounters and hospitalization compared with no receipt of an updated vaccine dose among immunocompetent U.S. adults during a period of multiple cocirculating SARS-CoV-2 Omicron lineages.


This research shows that there is a high level of effectiveness of the updated COVID-19 vaccines against serious outcomes such as emergency department and urgent care visits along with hospitalization.

These results imply the following:

  1. Even if you contract COVID-19 after vaccination, there is a lower risk of requiring further medical attention, such as hospitalization.
  2. The vaccines lower your risk of contracting the disease, so there is a lower risk of further medical attention.
  3. Those who have not had the updated COVID vaccines are much more susceptible to needing further medical attention if they contract the disease.

This is just more data that getting the updated COVID vaccines provide excellent protection against serious medical outcomes.


Michael Simpson

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