The US government is urging Americans to get vaccinated against the flu before the flu season sets in. And the Centers for Disease Control and Prevention (CDC) says there are more doses ready to administer this year than ever before, nearly 132 million of them.
The flu is not an illness to be complacent about said Dr Julie Gerberding, head of the CDC, earlier this week. Calling flu a “formidable foe”, she urged Americans to get vaccinated ahead of the flu season, which usually starts in November and peaks around February.
The flu shots are not just for people at risk of dying from the flu, they are for anyone who wants to avoid a week of misery, pain and discomfort.
Also, injection is not the only way to get vaccinated against the flu: there is a nasal spray version. In fact earlier this week the Federal Drug Administration (FDA) approved to extend the use of such an alternative, FluMist (made by MedImmune), from the current age range of 5 to 49 to include 2 to 5 year olds. This should make it easier for young children frightened of needles to get vaccinated.
Despite the campaign every year to encourage mass vaccination, the response has been very poor, according to new data from the CDC, and the take up varies widely across the country.
Every year a new vaccine is prepared that contains three strains of influenza virus. Two strains are of Type A (H3N2 and H1N1) and one strain is of Type B.
The decision as to which strains to use is made by trying to forecast which strains from the last flu season are most likely to cause infections in the coming season. The forecasting model uses the actual surveillance-based infection rates from the previous season.
Data from nearly 120 influenza surveillance centres in over 80 countries is analyzed every year by four World Health Organization (WHO) Collaborating Centers for Reference and Research on Influenza. One is based at the CDC in Atlanta, US; and the other three are in London, UK, Melbourne, Australia, and Tokyo, Japan.
Based on this analysis the WHO recommends which strains countries should use to make their batch of vaccines for the coming year. For the Northern Hemisphere the forecast is made in February and for the Southern Hemisphere it is made in September.
In the US the FDA makes the final decision as to which flu strains to use in vaccine production. Because of the manufacturing lead times involved the timescales are very tight and some manufacturers make their own prediction as to which strain is going to be recommended so they can start their production cycle earlier.
This year, the CDC is keeping a close eye on a strain called H3N2/Brisbane-like that has make an appearance at the end of Australia’s flu season. It is too late to incorporate it into this year’s vaccine batch, so if it makes an appearance in the US the vaccinations will not give full protection against it but it will give some, said the CDC, so it is still worth getting vaccinated.
About 1 in 5 Americans is infected with flu every year, and every year around 200,000 people end up in hospital and 36,000 die because of the flu.
High risk groups include the over 50s and the under 5s, women who are pregnant, anyone with a weak immune system or a chronic illness, and anyone with asthma or heart disease.
Relatives and carers of people with the flu could pass it on to other vulnerable people if they catch it, and the authorities recommend they get vaccinated too even though they may not be in a high risk group themselves.
This brings the total number of Americans who should be vaccinated each year to just under 220 million. However, the number that actually get vaccinated falls considerably short of this figure. Last year 18 million of the 120 million vaccinations had to be thrown away because of lack of demand.
The CDC has a new website on Influenza from which you can download a range of free materials aimed at high risk groups including caregivers and parents of infants, children with asthma and diabetes; and adults who live with seniors who are at risk.
Written by: Catharine Paddock