The curious case of the delayed flu

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All I hear these days are the sounds of sniffles, coughs and sneezes.

The weather in Regina has finally started to become a little less brutal and a little more warm and forgiving. But before people can breathe a “warm” breath of relief they must win against the antagonist that rears its head every once a while and particularly when the weather transitions: the flu.

The winter of 2025 has been full of surprises with multiple snowstorms, temperatures remaining consistently around -30°C or less for weeks in Regina and the surprisingly late onset across the country of the annual influenza season . People usually brace themselves for the flu’s arrival in late December, with the number of cases peaking in early January. This year however there has been a noticeable delay in the onset of the flu season which has caught people off guard. In a conversation with CBC, Dr. Karim Ali, medical director for infection prevention and control and head of services for infectious diseases at Niagara Health in Ontario, said, “We haven’t seen this amount of influenza cases as well as severe illness in almost a decade.” Clearly the flu has not only arrived late but also with increased virulence.

The flu’s late onset can be attributed to a confluence of factors. Global warming can actually be one of the reasons for the late onset of the flu. Unseasonably warm temperatures in the early winter months affect the influenza virus’s ability to infect people. A research study published by the university of Colorado in 2023 explains that the flu virus tends to thrive better in colder and drier conditions and warmer weather hinders its ability to infect its hosts.

People have also become more cautious with hygiene and health practices after the COVID-19 pandemic. Additionally, they expect influenza to strike in the earlier months. Increased vigilance on people’s end may also have reduced the spread of the virus in early winter months from one individual to another.

Building on increased vigilance, the rate of vaccination is also higher in the early winter months which provides a certain degree of immunity within the community against the virus in the early stages. Especially for previously known variants of the virus for which effective vaccines are already present.

Curiously enough, sometimes the spread of another virus can hinder the spread of influenza as well. Other viruses such as the Respiratory Syncytial Virus (RSV), which also infects people in the early winter months, can sometimes cause a “traffic jam” in the respiratory system. It can thus block the flu virus from spreading by preventing it from gaining a foothold in the respiratory tracts of hosts. A CBC report states that the number of flu cases saw a rise in 2025 when RSV cases declined.

Perhaps the most important reason behind the flu arriving late and with increased virulence is the emergence of more infective strains of influenza. Viruses mutate rapidly to avoid host immune responses. As a particular strain of influenza mutates, it can sometimes give rise to new strains which are better at infecting human hosts and spread rapidly from one person to another. These strains can even manage to avoid vaccine-mediated immunity which we get from flu shots. A new variant of influenza can explain the late onset and larger spread of influenza in 2025.

It is however important to keep in mind that these factors intertwine and influence each other. This makes it harder to isolate a single cause. That being said, it is important to take care of oneself as well as those around us. Flu can strike at any time of the year and taking proactive steps can ensure prevention of infection or if infected it can reduce the probability of health complications and the spread of infections.

Flu vaccinations are indispensable in conferring immunity against not just one but at times multiple strains of the flu virus expected to be in circulation. Vaccination prepares the body’s immune system for any future attacks from the virus. Especially in individuals with previously compromised immunity, vaccination can prevent infection or significantly reduce the severity of symptoms if an infection does happen to occur. Getting regular flu shots should therefore always be on everyone’s health-related itinerary.

Proper hygiene practice is another major step to prevent infections. Viruses belong to the class of disease-causing organisms which are called obligate parasites. This means that a virus has no means of reproducing and producing more of its kind unless it is inside its host, which in this case are humans. This explains why prevention of infection is far more important that treating an infection.

It is therefore imperative to properly wash hands, maintain social distancing, wear masks and observe other measures that can physically stop the flu virus from spreading from one person to another.

At times however, despite our best efforts, infections do occur, that is where having a healthy lifestyle can help. Having a balanced diet, taking time to exercise and having proper sleep cycles can boost the body’s natural immunity and its ability to cope with infections.

It is also important to seek medical help early on if one experiences flu-like symptoms. Getting help early can reduce the probability of developing serious symptoms. Isolation while recovering is a must, too.

Ultimately, staying informed and on top of things is a person’s best defence against viral infections. Reliable sources like the Center for Disease Control and Prevention (CDC) and the local health department can provide valuable information about circulating flu strains, vaccination recommendations and preventive measures.

Whether it be late or early in the season, dealing with circulating viruses and mitigating the probability of the spread of infection is not the just a responsibility of the healthcare staff but a community effort. Healthy habits, healthy lifestyles along with research-backed medical assistance are our best allies in the fight against influenza.