If a person contracts COVID and influenza at the same, which leads to a flu infection then it can be termed as a co-infection.
With the onset of winter, the chances of contracting COVID and flu increase significantly. And, now World Health Organisation (WHO) has warned that, there might be a rise in Covid-flu coinfection cases too. Last week, WHO official Maria Van Kerkhove tweeted that there could be widespread circulation of COVID19 & flu (& other pathogens) this winter. But, she has specifically urged all not to use the term 'twindemic' to describe the disease are call it infection on infection. Here's all that you need to about COVID and flu coinfection.