Imaging and COVID Vaccine Effectiveness

In the debate over how long the protection from COVID-19 vaccines last, radiology has now entered the chat. A new study in Radiology shows that people with COVID who got vaccinated more than eight months before COVID diagnosis had more severe clinical findings on imaging exams. 

The rapid development of COVID vaccines and their rollout worldwide has been one of the biggest public health success stories of the last 100 years. 

  • Still, even the most effective vaccines lose their potency over time, and COVID vaccines are no different. 

The question is, how long does the COVID vaccine’s protection last? 

  • Previous research documented a decline during the Delta and Omicron waves in vaccine effectiveness against hospitalization, from 92% to 79% after 224-251 days, and a drop in efficacy against death from 91% to 86% after 168-195 days in those with severe COVID.

To shed more light on the issue, researchers in South Korea performed imaging exams on 4.2k patients with COVID from June 2021 to December 2022. 

  • They correlated the severity of clinical outcomes like pneumonia visible on imaging exams to the length of time between patient diagnosis and when they had been vaccinated. 

Compared to those vaccinated in the last 90 days before COVID diagnosis, people vaccinated more than 240 days …

  • Had almost twice odds of severe outcomes (OR = 1.94)
  • Had higher odds of severe pneumonia on chest radiographs (OR = 1.65)
  • But there was no difference in the odds of severe outcome between those vaccinated in the last 90 days and those vaccinated 91-240 days before diagnosis

In an interesting wrinkle to the study, the researchers found no statistically significant difference in odds of severe pneumonia visible on chest CT scans between those vaccinated more than 90 days before diagnosis and those vaccinated within 90 days.

  • The authors proposed that the low use of CT for pneumonia assessment in their study population (20%) and its use primarily for critically ill patients could have introduced bias into the results. 

The Takeaway

The new findings shed light on the declining potency of COVID vaccines over time and could inform public debate over the length of time between boosters. The research also dovetails with other studies showing that the vaccine’s effectiveness does indeed begin to wane at six months.

Developing the Eighth Modality

Radiology has adopted seven mainstream modalities over its 127 years, and 4DMedical is determined to create the eighth imaging modality with its new XV Scanner.

The XV Scanner would be the first dedicated lung imaging system, giving radiologists four-dimensional and color-coded visibility into patients’ lung airflow and blood flow, and potentially a new way to assess lung diseases. 

  • The XV Scanner integrates fluoroscopy with advanced analytics software, producing qualitative and quantitative 4D lung function metrics 
  • It simultaneously acquires images from different angles, then measures lung tissue motion, and calculates ventilation at each breathing stage and every lung location
  • XV scans take 5 seconds to perform and deliver less radiation than a typical chest X-ray

4DMedical’s XV technology is also backed by a growing number of positive clinical studies, solid post-IPO funding, and an impressive expansion across Australian imaging giant I-Med Radiology’s 250 locations.

Although the XV Scanner hardware is still forthcoming, 4DMedical will initially launch XV software that can be installed on existing fluoroscopy systems (FDA cleared for ventilation, later adding perfusion) and will also support existing CTs in the future. 

  • Software-only might prove to be a logical starting point, providing 4DMedical with a low-friction way to demonstrate XV’s impact on patient care and test whether this impact is great enough to entice imaging departments to add a whole new scanner to their fleets.

The Takeaway

Creating medical imaging’s eighth mainstream modality might be among the most ambitious goals you’ll hear at RSNA 2022, but if the XV Scanner proves to be much better than existing lung imaging techniques, radiology might have to make room for one more.

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