Dr Gavin Jamie, a clinical researcher within the Oxford-RCGP RSC, is eager to share his knowledge and heighten awareness within the primary care sector. Therefore, we would like to introduce to you our first blog in a series that will look at various aspects of primary care including important topics such as circulating viruses. quality data/coding and vaccinations. We will also look at recent publications and news stories.
Influenza is commonly thought of as a seasonal virus which comes to a peak in January or February each year. It never completely goes away though and there are very few weeks when we don’t pick it up on at least one sample.
There are two common types of flu virus that we look for in the UK – types A and B. Influenza A is most common, especially in adults and tends to be a little more severe. It is also the type that produce epidemic infection which we last saw in the UK with Swine flu in 2009. That virus has adapted and is now part of our regular annual wave of flu.
These Influenza A viruses are commonly named after two of the proteins on their surface, haemagglutinin and neuraminidase – each type receives a number. The current types most commonly seen in the UK are H1N1 and H3N2 and we can test for these from swabs to see which is most active. Haemagglutinin helps the virus to bind to cells in the respiratory tract. There are three types of haemagglutinin (H1, H2, H3) that can infect humans. We currently test swabs for the H1 and H3 types.
There are many other types, and we can see a flu pandemic when a new type appears that people have little immunity to – either through previous infection or vaccination. The last time that this happened was “swine flu” in 2009-10. Many animals have their own flu viruses and can act as a reservoir of the virus. You might have heard about H5N1 which has been active in birds around the UK over the winter although H5 type does not allow the virus to be transmitted between humans.
Influenza B also has two main types, Victoria and Yamagata although it is thought that Yamagata may have become extinct around the time of Covid pandemic. It is a little more common in younger children and throughout the year.
Current flu vaccines contain protect against four different strains of the influenza vaccine, two A and two B. The vaccines are important as flu can be a serious disease in a minority of people, particularly the very young, the old and those who have other long term diseases. There are a significant number of deaths each flu season due to the virus and some of these can be prevented by vaccination.
Flu can change quite quickly and the vaccine takes nine months or more to produce. Every year the World Health Organisation makes a prediction of which viruses are most likely to cause significant disease and which strains the vaccine should protect against. Most of the time this is correct but, like any prediction it is sometimes wrong.
Taking swabs from people with symptoms can not only tell us which viruses are in circulation but, if we can combine this with information about who has had the vaccination, we can also find out how effective the vaccines have been. Both of these are important pieces of information. In recent years we have seen changes not only in the viruses that the vaccines protect against but also in the type of vaccines that are given. People who are over 65 years old now have a boosted (“adjuvanted”) vaccine which increases its effectiveness.
The flu virus contains RNA genetic material surrounded by a thin envelope with proteins attached