University of Waterloo Study Reveals Vaccine Effectiveness Against COVID Variants

A recent study from the University of Waterloo has examined the effectiveness of current COVID-19 vaccines against newer strains of the virus. Conducted by a team including Yangjianchen Xu, an assistant professor in the department of statistics and actuarial science, the research analyzed data from approximately 1.8 million residents of Nebraska over a seven-month period from 2024 to 2025. The study aimed to evaluate how well vaccines are performing as the virus continues to evolve.

The observational study utilized data from the Nebraska electronic disease surveillance system, the hospital discharge data system, the Office of Vital Records, and the state immunization information system. Collaborating with researchers from the UNC Gillings School of Global Public Health and the University of Nebraska Medical Center, the team sought to fill gaps in existing research regarding vaccine efficacy.

Key Findings on Vaccine Effectiveness

Xu highlighted that the findings demonstrate that the latest vaccines remain particularly effective against severe outcomes of COVID-19, such as hospitalization and death. The study found that vaccines were most protective four weeks post-vaccination, showing an effectiveness of 44.7 percent against infection, 45.1 percent against emergency department visits, and 57.5 percent against hospitalization or death. However, effectiveness declined over time, dropping to 35 percent against infection at ten weeks and further to 16.7 percent by twenty weeks.

“This is the largest study I know so far about this vaccine,” Xu stated. “It’s important to have that sort of large sample to accurately estimate the effectiveness of the vaccine.” He anticipates that as the COVID-19 virus continues to evolve, new versions of the vaccine will be developed, and he hopes to extend this research to assess their effectiveness.

The lead author, Danyu Lin, a distinguished professor in the department of biostatistics at the Gillings School, emphasized that their research indicates that vaccines available during 2024-2025 are effective, especially against severe outcomes, although effectiveness diminishes over time. “Our study also showed that vaccine effectiveness was similar against different Omicron subvariants,” Lin added.

Public Health Implications and Recommendations

As winter approaches, public health officials are urging individuals to stay updated with their vaccinations. Dr. Nicola Mercer, the medical officer of health for Wellington-Dufferin-Guelph Public Health, noted that respiratory viruses, including COVID-19 and influenza, tend to spread more easily in colder months. She stressed the importance of vaccination not only for personal health but also for protecting vulnerable populations.

“If you have a newborn in your family, very young children, or elderly relatives, you can actually make other people ill,” Mercer stated. “We’re really encouraging those people to get the vaccines.” She also advised anyone skeptical about the vaccine to consult with healthcare providers to understand its significance as part of annual health checks.

David Aoki, the director of infectious disease and chief nursing officer with Region of Waterloo Public Health, echoed these sentiments, highlighting the continuous availability of free COVID vaccines. “Study after study have shown the effectiveness of them [vaccines] and the safety of them,” he said, urging the public to get vaccinated, particularly during the winter months when the risk of transmission increases.

As the research from the University of Waterloo underscores, remaining vigilant and proactive regarding vaccinations can significantly impact public health outcomes as society continues to navigate the evolving landscape of COVID-19 and its variants.