A new study from the University of Waterloo analysed how COVID-19 continues to evolve within the dominant Omicron family and assessed whether current vaccines remain effective against these emerging sub-variants. The research underscores the importance of annual COVID-19 vaccination, particularly as immunity from previous doses wanes and the virus undergoes subtle genetic shifts.
While the early years of the pandemic saw dramatic variants such as Alpha, Delta, and Omicron, today’s changes in the virus are more subtle but still significant.
“There are no brand-new variants of concern this year, but the virus undergoes subtle shifts all the time,” said Dr. Matthew Tenenbaum, Associate Medical Officer of Health at Wellington-Dufferin-Guelph Public Health. “These shifts can affect immunity, which is why annual vaccination remains important.”
Dr. Yangjianchen Xu, a professor in the Department of Statistics and Actuarial Science at the University of Waterloo and co-author of the study, said multiple JN.1-related lineages dominate in 2025, including KP.2, KP.3, LB.1, XEC, XFG, and LP.8.1.
“These are all descendants of the Omicron JN.1 variant, differing mainly in spike-protein mutations that improve immune evasion,” Xu said.
The study found that updated 2024–2025 vaccines provide strong but time-limited protection. Four weeks after vaccination, researchers observed a 44.7 per cent reduction in symptomatic infection, 45.1 per cent reduction in emergency department visits, and 57.3 per cent reduction in hospitalisation or death. At 20 weeks, effectiveness declined but remained meaningful, especially against severe outcomes.
“Updated vaccines significantly enhance protection against current JN.1 subvariants,” Xu said. “Every updated dose consistently lowers hospitalisation and death rates, even after accounting for prior vaccination and infection.”
Locally, vaccine uptake has fallen sharply since 2021, when more than 500,000 doses were administered to a population of roughly 300,000–350,000. In 2025, only about 39,000 doses have been delivered so far. Tenenbaum said the drop reflects lower perceived risk and milder symptoms for many people.
“COVID-19 doesn’t hold the same level of concern it once did,” Tenenbaum said. “Many individuals experience only mild symptoms like a runny nose or cough and may question the need for vaccination.”
Xu noted that while new JN.1 lineages are not inherently more dangerous, they pose challenges because of high transmissibility, immune evasion, and low booster uptake—especially heading into a season when influenza and respiratory syncytial virus (RSV) circulate simultaneously.
“We could face a difficult winter season due to overlapping respiratory threats and declining vaccine confidence,” Xu said.
Symptoms of current COVID-19 remain largely consistent—fever, cough, sore throat—and overlap with other respiratory viruses. Public health guidance now treats COVID-19 similarly to influenza and RSV: stay home if sick, get vaccinated annually, and consider mask use in crowded indoor settings.
Updated vaccines became available for high-risk groups on September 22 and for the public on October 27. Children under five without a primary care provider can access shots through public health clinics.
“Vaccines are developed to best match the variants predicted to be most prevalent,” said Region of Waterloo Public Health. “Staying up to date every year is critical. Vaccination is the best defence against serious illness.”
Local health systems are better prepared than in early pandemic years, with surge planning in place and antiviral treatments available for high-risk patients.
Tenenbaum said the study reinforces a simple message: “Even if individual risk feels lower than in 2020 or 2021, vaccination protects not only you but the broader community. It’s a small effort for significant protection.”
The University of Waterloo research serves as a reminder that while the virus continues to evolve, updated vaccines remain highly effective, safe, and cost-saving—particularly for older adults. Staying current with boosters, researchers say, is the most reliable defence against serious illness and long-term complications.
Contributed Photo/Sangjun Han
