By Dr Jeremy Rossman
Thousands of people are reporting coming down with bad colds following the relaxing of lockdown measures, UK Health Secretary data shows.
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.
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now, is what to expect for the coming winter given that the use of COVID-19 preventative measures have largely been repealed in the UK.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.