Winter viruses are back and it’s time to rethink our defences

Flu and COVID-19 aren’t going away. Vaccination, ventilation, and masks still matter, even if they’re not perfect

Winter is coming, and with it the usual surge of respiratory viruses. Every year, we see an epidemic of influenza (the flu), and now that COVID-19 has shifted from a pandemic to a regular seasonal virus, it is also is likely to rise in winter. 

Influenza or COVID can knock a healthy person flat for three to four days. Most recover, but some develop serious complications. Older adults and those with chronic conditions (such as heart or lung disease, diabetes or cancer) face highest risks, and some will die. 

These viruses spread through droplets and aerosols — tiny particles that float in the air and can penetrate deep into the lungs. Aerosols are created when people shout, sing, cough or sneeze. Indoors, without good ventilation, the concentration of virus particles can build quickly. Outdoors, they disperse. A person can be infectious one or two days before symptoms begin and for a few days after the illness starts.  

How can we protect ourselves?

Protection from viral infections comes from three things: immunization, masking, and hygiene. These work as layers of defence. None is perfect on their own, but together they provide strong protection. 

Vaccination

Vaccines offer strong protection. In Alberta, we are part of the four -province Sentinel Practitioner Surveillance Network (SPSN), that has tracked influenza vaccine effectiveness for 18 years. Flu vaccines reduce your chance of infection by 40 to 70 per cent.

Most years, each of us has about a 30 per cent chance of getting influenza. Cutting that by half would mean that one year in six we would avoid an attack, while one year in six we would still get an infection. This is indeed imperfect, but the vaccine also reduces hospitalization and deaths. Each winter hospitals overflow with patients who have severe infections. It would be great not to be one of them. 

In the four years since COVID-19 spread through the world, nearly everyone has had an infection, and most have had more than one. Therefore, most of us have an immune response to the virus that is partially protective. However, like Influenza, the virus changes rapidly so immunity reduces over time. 

COVID-19 vaccines offer similar partial protection as influenza vaccines. The SPSN found that newer COVID vaccines reduce infection risk by about half for the first three months. Protection fades over time, but boosters still help, especially in preventing hospitalization and long COVID. Governments should make it easier and more affordable to stay protected. 

Masks, ventilation, and hygiene

Masking also works, again, imperfectly, but measurably. Even basic surgical masks reduce the amount of virus people breath out and take in. N95 masks provide even stronger protection. In crowded or poorly-ventilated spaces, wearing a mask is a smart precaution for those who are worried about infection. 

Air purifiers with HEPA filters are also useful to reduce viral particles. These are best if installed in heating and air-conditioning systems, but in-room air filters also reduce virus concentration. 

We can reduce the risk of infection from winter viruses using vaccination, masking, better ventilation and air filtering, along with hygiene and hand washing. This not only benefits ourselves and our families, but also the community. If we do not get infected, we will not pass it to those around us. Reducing infections reduces the overload from winter epidemics and enables clinics and hospitals to continue caring for all other health issues, from broken bones to chronic disease. 

This winter let’s re-think our defences. No single solution is perfect, but together, we can keep more people healthy. 

Dr. James A. Dickinson, MBBS PhD FCFP 

Adjunct Professor, Departments of Family Medicine and Community Health Sciences, Cumming School of Medicine, University of Calgary

Member, O'Brien Institute for Public Health