A simple question at the pharmacy counter
An older adult stands in front of the vaccine booking screen. The flu shot is easy. The COVID shot gives them pause.
Does it still work? For how long? Is it worth rolling up my sleeve again?
Quebec just ran one of the largest real-world checks on those exact questions — and the numbers are honest, useful, and a little sobering.
Why this keeps mattering
COVID has not gone away. It has settled into a pattern of waves, especially in winter and late summer. And the people most likely to end up in the hospital are still adults over 60, particularly those with chronic conditions.
Each year, the vaccine is retuned to match the strains in circulation. The 2024/25 version was targeted at the KP.2 sub-variant of Omicron.
Governments keep offering free boosters to older adults. But uptake has slipped — partly because people are not sure how much protection they actually get.
The old question, the new answer
Earlier studies suggested COVID vaccines prevent severe illness but fade over time. This new Quebec analysis puts a clearer number on both parts of that story.
It confirms the shot works. It also confirms the protection is short.
That dual finding is important. Neither cheerleading nor dismissing the vaccine is supported by the data. The truth sits in between.
How the study worked
The researchers used a test-negative design. That is a clever way of comparing vaccination rates between people who went to the hospital with COVID-like symptoms and tested positive versus those who tested negative.
If the vaccine works, vaccinated people should be overrepresented in the test-negative group — because the shot kept them from catching COVID in the first place.
This design controls for who bothers to seek care, which is a major bias in old-style vaccine studies.
The team pulled records from Quebec adults over 60 tested in acute-care hospitals between October 2024 and August 2025. They linked vaccination history, hospital data, chronic disease records, and lab results.
Just under 50,000 of the 116,000 participants — about 43% — had gotten the updated shot.
Overall vaccine effectiveness against COVID hospitalization was 34%. That means among people who would have otherwise been hospitalized, the vaccine prevented about one in three cases.
Not dramatic. But not small — especially for a population at higher baseline risk.
The effect was strongest in the first eight weeks after the shot: around 43% protection against hospitalization.
Then came the fade. By roughly 32 weeks — about eight months — protection had dropped to near zero.
Here's where the honest part lives
A 34% average with fading tails is not a failure. It is a realistic picture of a vaccine against a virus that keeps shifting.
Many treatments we accept as useful have similar or lower numbers. Statins prevent a smaller percentage of heart attacks than this vaccine prevents hospitalizations. Seasonal flu shots often hover in the same range.
What this study does is remove the guesswork. You can now plan around it.
An expert lens
Public health researchers have been warning for two years that the era of "one and done" COVID vaccination is over for older adults. Immunity from mRNA and similar shots wanes within months, not years.
This Quebec dataset — large, recent, and real-world — puts a concrete shape on that warning. It also suggests that timing matters more than people realize. Getting the shot too early in the season means the protection may be fading by the time winter waves peak.
That argues for aligning boosters with your local surge pattern, not just with the first day they become available.
If you are over 60 and in Canada, the U.S., or a similar country, the practical takeaway is simple.
The booster is worth getting, especially if you have chronic conditions or live with someone vulnerable. It will not make you invincible, but it measurably lowers your chance of ending up in a hospital bed during an active wave.
Timing matters. If your region typically sees COVID peaks in December and again in summer, getting boosted in October or early November gives you maximum coverage right when you need it.
Talk to your pharmacist or doctor about the best window for your area.
The limitations you should know about
The study was observational, not a randomized trial. Even with careful statistical adjustment, vaccinated people may differ from unvaccinated people in ways that skew results.
It also only measured protection against hospitalization — not against milder infection, long COVID, or transmission.
And the waning curve will look different for a younger, healthier population. These numbers apply specifically to adults over 60.
Two things are likely to shape the next round. First, ongoing work on longer-lasting COVID vaccines — including mucosal (nasal) versions — is under way.
Second, expect public health agencies to push for better booster timing rather than just higher uptake. A shot given at the right moment may be worth two given at the wrong one.
Until then, short-lived protection is better than none — as long as you know what you're getting.
