By Emma Wilkinson
BBC News health reporter
It is the time of year when coughs, colds and flu seem to spread like wildfire.
Scientists hope to learn more about how flu is transmitted
One person in the office gets sick and it is not long before half the workforce has taken to their bed.
And all those Christmas parties probably aggravate the situation as we mix with more people than we usually would.
But how much do we actually know about how colds and flu spread - for example how many others does one cold sufferer infect?
Researchers are hoping a big-brother style experiment will provide some answers, at least where influenza is concerned.
Next year, Professor John Oxford, an expert in virology from Queen Mary's School of Medicine and Dentistry, in London, will lock volunteers in a hotel for a week, deliberately infect some with the flu virus, and wait to see what happens.
"To start with, we'll take 15 volunteers, with no immunity to the particular flu virus and infect five of them," he said.
"Using CCTV, we'll keep an eye on them and look for patterns of transmission."
It will be the first study looking at the spread of flu by directly infecting volunteers and sitting back to see what happens.
Knowing how easily flu can spread will help officials planning for pandemics, said Professor Oxford who is applying for government funding for the research.
"The second phase will be seeing if we can break the chain of transmission with things like hand-washing or wearing a hygiene mask."
He hopes the experiment, being done with Professor Jonathan Van Tam from Nottingham University, will get underway next year.
It is certainly true that "coughs and sneezes spread diseases".
And it would also seem to make sense to stay away from work or school to avoid sharing the bugs around.
But there are a fair few gaps in our knowledge when it comes to the common cold, says Dr Douglas Fleming, director of the Royal College of GPs Research Unit in Birmingham.
"The problem is the common cold is not thought to be serious enough to investigate properly," he said.
COLDS AND FLU
Colds and flu are both common respiratory illnesses caused by viruses
Whereas there are hundreds of different types of cold viruses, flu is caused by the influenza virus of which there are three major types, A, B and C
The influenza virus constantly changes its structure which is why a new vaccine has to be developed every year
A cold lasts only two to four days and causes a stuffy or runny nose, sneezing, sore throat, cough, mild fever and tiredness
Flu is more severe, can last a week or more and is associated with a high fever, chills, headache, intense muscle pains, exhaustion, loss of appetite, cough and sometimes a blocked nose and sore throat
"Nearly everyone gets better so there isn't the attention given to it, but I think we should be trying to get to know much more about common respiratory infections."
For example, he said people might complain that colds seem to last longer than they used to but is that a sign of age or a sign of the changing nature of the cold virus.
"We don't have the facts - I can say I've never had a cough like that before but is it because you shake things off better in your youth.
"Whether people are having colds that last longer than they did years ago we simply don't know."
He said much of the lack of understanding around colds could be solved by more investment in surveillance.
It's not even entirely clear why we get more colds in winter.
Over, the past decade there has been much research into the structure of the cold virus with rhinovirus - one of the most common cold viruses - being the most understood.
This includes how it attaches to the lining of the nose to cause infection.
However, even with this information it is unlikely there will ever be a "cure" for the common cold for several reasons.
A cold is caused by many different viruses, by the time you know you have a cold it is probably too late to treat it, and as colds are fairly minor and self-limiting any side effects from medication, however minor, would probably not be worth the hassle.
Also there would be dangers of viruses becoming resistant to effective medications, rendering them useless, just as we are seeing with antibiotics.
So what do we know about colds?
Well according to the Common Cold Centre at Cardiff University, it has been estimated that adults suffer two to five colds per year, and school children may suffer seven to 10 colds per year.
Children to blame
Young children are mainly responsible for spreading common cold viruses and infection usually occurs at home or in the nursery or school.
The incubation period for a common cold is usually around two days before the symptoms begin and a person is most infectious when they are in the early stages of sneezing, runny nose and cough.
Professor Steve Field, chair of the Royal College of GPs said there is certainly a lot of cold and flu circulating this Christmas and it's hard to avoid catching one.
"We really need to try and encourage children and adults to use handkerchiefs and afterwards wash their hands, so if you're shaking people's hands and if you're in close contact you prevent passing it on.
"But if you have got really horrible flu, the only thing to do is stay away from people," he said.