Q My husband has low back pain, and says we should lie on a very hard mattress. I feel much more comfortable on one that will give' a little more. Do I really have to change our mattress for his sake? I don't have back pain.

A You asked this question at the right time! About four years ago a really well-conducted trial of types of mattress for back pain sufferers was published. It showed that over 90 days, people with back pain did better sleeping on medium firm than on very firm mattresses. So you don't have to sleep on a hard bed - a reasonably firm one will do. You need a little give' that will help the mattress mould around your shape. I've found that memory foam mattresses or a mattress topped by a memory foam cover has helped people with back pain. It should help both of you to sleep.

Q My neighbour gives her eight-year-old son echinacea every day to ward off colds and flu. She also gives him added vitamins. She says I'm neglectful of my children for not doing so. What do you think?

A Colds and flu are virus infections that are passed from child to child (or adult) by inhaling droplets of saliva from a cough or sneeze. You are susceptible to the infection regardless of how much vitamin or any herbal or other medicine you have in your body. Echinacea does not kill viruses and there is no controlled trial to show it protects against any infection. There are plenty of trials to show that in a developed country extra vitamins don't protect against these infections. So be confident that you are doing the right thing by your children. All you need to ensure is that they eat a good range of food, take normal exercise, get normal amounts of sleep, and are confident in their good relationship with you.

Q Flu has hit our area and I wasn't vaccinated against it. Is it a good idea to get vaccinated now?

A January is too late for a flu virus that is around now (though there isn't much evidence of it yet this winter). The vaccine takes about two weeks for your antibodies to build up to a level that would protect you against the current virus, and by that time you would have been almost certainly infected. A true flu epidemic takes only about a month or so from start to finish. However, the injection will help you against any other flu germ that might come along, say in a month's time or more. So if you are susceptible to serious reactions to flu (say if you have a chronic chest or heart problem or are on immune suppressant treatment or have had a transplant) there is still time for a jab'. If you are young and normally healthy, you shouldn't take up an injection that could be given to someone else. If you do take the injection in the next few days and then get flu within the next fortnight, don't blame the vaccine. Your symptoms will be due to the current virus - you will have been incubating it at the time, or just after, you had the injection.