Chris -   Well, actually, it’s part right, part wrong.  Mostly part wrong.  The “feed a cold” is absolutely right.  A “starve a fever” is probably absolutely wrong.  There was a paper that got published and we reported it on The Naked Scientists last year - in the Physiological and Biochemical Zoology journal by Lynn Martin. She reported taking deer mice and starving them, in other words, they gave them 30% fewer calories than they would normally need in a day.  The mice didn’t show any obvious behavioural differences compared with well-fed mice.  But when they did blood tests on them they had far fewer memory B cells.  These are the cells that make antibodies that defend you against infections in the future.  So this shows that if you aren’t getting a good enough diet you will therefore have too little energy to put into mounting an effective immune response and therefore you’ll be more prone to an infection in the short term and more prone to an infection subsequently as well.  This also fits with other studies that have been done where people receiving measles vaccine have been followed up.  People who weren’t eating enough had far fewer anti-measles antibodies subsequently compared with people who are much better fed.  So, you should always ‘feed a cold’ is the moral of that story, but you should definitely not “starve a fever.”

Helen -   I just try and eat a thing, basically.  And if you’re feeling awful, try and get something down.  Exactly.

Chris -    Basically, you need energy to master your immune response.  You have to grow lots of cells.  And that takes energy.  And you got to feed yourself.

Helen -   Makes sense.

Chris -  The answer is that you put the vaccine virus into the egg, which has a chick inside.  The chick turns into chicken soup with some 'flu added.  You get the 'flu out, purify it and you end up with about three doses per egg. 

So, if you do some maths, if you want to immunise the entire population of the U.K. with, let’s say (for "eggs-ample"), 60 million to make the numbers easy, you would need - just for the U.K. - 20 million laboratory grade chicken’s eggs.  So a lot is the answer.

In terms of egg-safety, the eggs used are laboratory grade eggs.  They are high-grade, disease-free, guaranteed to be safe chickens' eggs.  And also, the testing that goes on is incredibly rigorous.  The eggs are tested, the vaccine progeny is testesd and what comes out is tested to make sure that there’s nothing in there that shoudn't be.

Chris -   The way flu gets hold of cells is down to proteins on the surface of the virus particle. Each virus particle is tiny, about 1/10,000th for the millimetre across.  If you could zoom in on the surface, you’d see that it had these spikes on the surface.  These spikes are a structure called haemagglutinin, which is a tiny protein resembling a molecular grappling hook.  It’s viral Velcro.  It gets hold of something called sialic acid, which is a chemical on the surface of the cells that line our nose and throat, and this enables the virus to grab hold of those cells and pull itself in very close. 

Through this interaction the cell thinks the virus is something that it has to take inside the cell.  So the cell then does something called receptor-mediated endocytosis, which basically means it pulls the virus inside the cell. Once inside the virus releases it’s genetic material and productively infects the cell.

It’s a bit like a Trojan horse actually because the Trojan horse was this juicy tidbit sitting outside the gate of Troy. The guys inside the city thought, “Wow!  That looks fantastic.  We’ll pull that inside because it looks good.”  And it goes inside the city.  And then of course, lurking inside are all these people who are then wreak havoc inside the city.  And that’s basically what a flu virus does.  It hijacks the cell, turns it into a virus factory and then it infects all of the cells around it and all the people around you!

Chris -  It depends what virus you’re dealing with.  If you’re dealing with 'flu, they work quite well because 'flu is what’s called an enveloped virus. On the surface of the virus particle is an oily bag which, if you add alcohol from a hand rub or cleansing gel, breaks it apart, denaturing the virus.

If, on the other hand, you’re playing around with something like norovirus, the winter-vomiting bug, this does not have one of these oily envelopes around the outside of the virus; these are known as non-enveloped viruses. Instead they comprise a very tough particle assembled from proteins linked together. As a result of it does not respond to alcohol in disinfecting hand rubs.  These are impervious to the alcohol in hand rubs, so these sorts of cleansers are not effective against viruses like noro. All all you get is a pure culture of norovirus on your hand after using one! Instead, the way to deal with these is actually soap and water; not because the soap kills the noro but by rubbing the skin actually detaches it and this gets rid of it.

Chris -   Well, we think flu spreads better in winter because of human behaviour because it does this reproducibly in every country in the world and in which it is winter time - it doesn’t mean it goes away completely in summer but it does come much more commonly in winter. 

We think that’s because it spreads better in winter because of what humans do.  We go indoors more in winter so there are more people together indoors with the windows closed.  Also, unlike summer time, it’s less light and therefore there's less ultraviolet radiation to dry out the virus and kill it.  So 'flu finds it easier to persist on surfaces spread by coughs and sneezes, and it hangs around for longer.

As a result you have a higher chance of passing it on so that’s what we think goes on.  And then the big determinant, the disproportionate determinant, is the school year.  The long summer school holiday powerfully knocks 'flu on the head because kids stop mixing and spreading the infection amongst themselves.  What normally happens is that they become infected and then go home and give it to their parents and the parents then carry the infection to all of the other parts of the social and age strata, usually through their workplace.