Why do we get a ‘common cold’ season and typically when does it occur in the UK?
Every winter we have the ‘cold and flu’ season when cases of respiratory virus infections increase. These winter respiratory viruses include the flu virus, which can cause severe infections, and rhinoviruses, which causes more mild ‘colds’, though there are many other respiratory viruses that spread in the winter.
In the UK the cold and flu season is typically between October and March and coincides with the onset of winter weather. It is thought that there are three main reasons for this seasonal increase in respiratory virus infections.
First, many viruses transmitted in the air by aerosols and respiratory droplets survive and spread better in cold, dry weather. Second, our behaviour tends to change in the winter, with people spending more time with others indoors where respiratory viruses transmit better. Finally, for many people, our immune systems do not perform as well in the winter, due to lower levels of vitamin D and melatonin.
Read more about viruses:
- Meet the scientist who defeated ‘the world’s worst bacteria’ to save her husband’s life
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How have COVID restrictions affected the cold season?
The 2020-2021 winter cold and flu season was unique in seeing some of the lowest rates of respiratory virus infections in recent history. It’s thought that this dramatic reduction was due to the COVID-19 precautions that we were taking over the last winter. COVID-19, just like flu and many winter cold viruses, spreads through the air.
Because of this, the measures that are so effective at reducing COVID-19 transmission, e.g. face masks, indoor ventilation, physical distancing and hand hygiene, will also be effective at reducing the transmission of many other respiratory viruses and their use is why we had such a mild cold and flu season last year.
What is a 'super cold'?
The question many of us are asking now, is what to expect for the coming winter given that the use of COVID-19 preventative measures have largely been repealed in the UK. It has been suggested that we might see a ‘super’ cold and flu season. It is possible that we will see a robust cold and flu season this winter where we have widespread transmission of ‘typical’ strains of cold and flu viruses.
In this situation, the infections would not necessarily be any more severe than in a typical winter - though a flu infection can still be very severe. This could occur because our collective immunity to typical cold and flu viruses may have waned over the past year and so more people may be susceptible to infection with these viruses.
We are already seeing indications of increased respiratory virus infections in children, specifically the dangerous respiratory syncytial virus, or RSV. Over the past summer we saw high levels of RSV infections in areas where COVID-19 precautions were relaxing. It is very possible the level of RSV and other respiratory viruses will continue to increase over the coming winter in areas without mitigation measures in place.
Read more about colds:
- Natural remedies: Can honey really help cure a cold?
- A scientist’s guide to life: how to beat a cold
- Can people have two colds at the same time?
Another concern is that there will be a ‘super’ strain of cold or flu viruses that will spread better or cause more severe disease, just as we’ve seen with some of the COVID-19 variants. Whilst there’s no specific super cold that we should be worried about, viruses like the flu continue to change and evolve during the course of the year. Thus, it is possible that the version of the flu virus that we see spreading this winter will be more severe or transmissable than we’ve seen before; however, there is no reason to assume that will be the case.
It is just as possible this year’s flu strain will be milder than we’ve seen in past years. Of greater concern is co-infection. Studies have shown that co-infections between flu and COVID-19 are possible and can greatly increase virus transmission and disease severity.
What are the best ways to protect yourself from catching or spreading a cold?
Regardless of the exact strains of cold and flu viruses that are going around this winter, we know what we need to do to reduce the spread and protect ourselves: wear face masks in indoor spaces, practice physical distancing, pay attention to hand hygiene, ensure good indoor ventilation and get vaccinated - both for COVID-19 as well as the flu. All of these measures will also help to protect against the spread of COVID-19, which still has high transmission rates in the UK and will likely continue to pose a risk to health and wellbeing throughout the winter.
