The flu season has began within the UK this yr – with cases rising weeks sooner than in previous years. This has led to fears that the UK is on target for one among its worst ever flu seasons.
In the UK and other Northern Hemisphere countries, flu season runs from mid-November to mid-February. In the Southern Hemisphere, it runs from May to July.
It is difficult to know the precise variety of flu cases the UK is currently seeing because most individuals don’t report having the flu. Most just stay in bed and recuperate. To get an image of this yr's flu season, we depend on hospital data and GP reports. It often only represents essentially the most severe cases of the flu.
We know that flu season “starts.” 10% of suspected cases Come back positive for influenza virus.
It's flu season within the UK Already well underway – and frequently before it starts. This is because at first of November we were already looking 11% of daily test Come back positive for the flu. At the identical time last yr, only 3% of tests were positive. The UK crossed the ten% threshold a full month sooner than last yr.
School-age children are currently essentially the most affected, with 38% test Coming back positive for the flu – up from 30% just every week ago. Around this time last yr, the number of kids testing positive for the flu was Just under 7%.
UK Health Security Agency
Similar increases have been observed elsewhere, akin to in Japan And All over Europe.
What is causing this early flu season?
UK flu vaccine increases look like roughly the identical as previous years, so the rise in cases can’t be explained by a drop in vaccination rates.
One possible factor contributing to the UK's early rise in flu cases is the strain of influenza virus that’s circulating.
The flu is brought on by influenza viruses – mainly the influenza A virus. There are many kinds of this virus, so that they are often designated by a mixture of H and N numbers. For example, H5N1 is the foremost reason for the continuing Avian flu epidemics In birds and other animals. Seasonal flu in humans is often brought on by H3N2 and H1N1.
The seasonal flu vaccine is designed to guard against these two strains, in addition to the influenza B virus. This vaccine is between 20-70% effective Flu prevention times by yr. This vaccine is best for school-age children, especially in prevention Severe forms of the disease.
A brand new vaccine is developed annually because circulating strains of influenza reduce the effectiveness of the vaccine over time.
Twice a yr (once for every hemisphere), the World Health Organization convenes an authority panel to determine, based on the strains circulating the previous yr, which influenza strain needs to be used. Make a vaccine For the upcoming flu season. Vaccines almost at all times include H1N1, H3N2 and influenza B strains.
In general, the formulation of vaccines based on those previously circulated is kind of effective. This is because there are not any genetic changes in these strains between flu seasons large enough to render the vaccine ineffective.
But it seems there was an exception this yr. A brand new strain of influenza, influenza A H3N2 subclade K, is now infecting the vast majority of people. is on this strain Seven variations which differentiates it from previous H3N2 strains. This is way more genetic variation between seasons than is often seen.
It is simply too early to know why this strain has developed so many genetic mutations. But we do know that these changes appear to have made this strain barely more transmissible than previous strains.
R number of stress . This implies that 20% more people can be infected than we might normally expect.
Preliminary research This strain suggests that the vaccine continues to be very effective in stopping severe types of the disease in children. But in adults, the effectiveness stays between 30% and 40%.
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However, we cannot yet say whether reduced vaccine efficacy in adults and latest mutations within the H3N2 strain are the explanations behind the present increase in flu cases.
It's also too early to know whether this yr's flu season can be more severe than previous years. But based on its early onset, the high R variety of the strain and the low effectiveness of the vaccine in adults, we are able to expect higher numbers than usual.
And, if we have a look at the Southern Hemisphere flu season data – that sometimes gives us a great idea of ​​what to anticipate. Worst flu season ever. They reported 10% more cases than last yr.
How to guard yourself
It's vital to notice that, especially in children, vaccines are still the perfect type of protection. The flu will be very severe in each young and old, leading to hospitalization and sometimes death. Vaccination (including by those that recurrently Get in close contact (with the elderly and the young) is essential.
It's also vital to know the way flu symptoms differ from the common cold so you’ll be able to recuperate and stop others from catching it. The presence of fever, headache and a powerful cough often indicates the flu.
If you will have these symptoms, you need to rest and follow up Standard flow guidance. Also do not forget that you might be contagious every week or so after symptoms start, so isolating at the moment will prevent the virus from spreading. Along with gagging, wearing a mask and following good hand hygiene can provide help to avoid getting sick and stop you from spreading the flu in the event you are sick.