# 6900
Even though I get the flu shot every year - and urge others to do the same - a frequent topic of discussion in this blog are the often disappointing influenza vaccine effectiveness studies we’ve seen – particularly among those over the age of 65.
As an example, in October of 2011, in CIDRAP: A Comprehensive Flu Vaccine Effectiveness Meta-Analysis, we saw a major review indicating the TIV (Trivalent Influenza Vaccine) - during 8 of 12 flu seasons (67%) – produced a combined efficacy of only 59% among healthy adults (aged 18–65 years).
They found the protective effects of the flu vaccine could vary considerably from one season to the next, as well as among different age groups (see Study: Flu Vaccines And The Elderly).
Some years, and in some cohorts, there was little evidence of protection.
Yet the CDC’s advice remains - that while less than perfect – The single best way to protect against the flu is to get vaccinated each year.
It’s a tough sell, however, convincing people to get the flu shot when we see effectiveness studies such as those that were published yesterday in the Eurosurveillance Journal.
I’ve likened it in the past to being like trying to market a bullet proof vest that is `guaranteed to stop roughly one out of two bullets’.
A couple of quick notes.
Last year’s flu season was late in coming in Europe (and almost non-existent in North America), and so the time between receiving the shot and the arrival of the flu was greater than most years, possibly accounting for some of the decline in vaccine effectiveness.
Also, this year’s flu shot incorporates an updated H3N2 strain.
So far, the VE (Vaccine Effectiveness) numbers being reported out of Canada and the UK (the first two studies) are higher (range 45%-51%) than those reported at the end of the previous flu season.
And a couple of weeks back, in FluView Week 1 & MMWR Vaccine Effectiveness Report, we saw the CDC’s first estimate of this year’s flu vaccine’s effectiveness, which they report as around 62%.
Some links this morning to this week’s Eurosurveillance Journal which is dedicated to vaccine effectiveness studies, and then a link to a CIDRAP NEWS report by Robert Roos that does a far better job of summarizing these studies than I could.
Rapid communications from the United Kingdom and Canada with 2012/13 mid-season estimates for influenza vaccine effectiveness and papers on end-of-season estimates for 2011/12
Eurosurveillance, Volume 18, Issue 5, 31 January 2013
by J McMenamin, N Andrews, C Robertson, DM Fleming, H Durnall, B von Wissmann, J Ellis, A Lackenby, S Cottrell, B Smyth, M Zambon, C Moore, JM Watson, RG Pebody
The early experience of the United Kingdom (UK) is that influenza B has dominated the influenza 2012/13 season. Overall trivalent influenza vaccine (TIV) adjusted vaccine effectiveness (VE) against all laboratory-confirmed influenza in primary care was 51% (95% confidence interval (CI): 27% to 68%); TIV adjusted VE against influenza A alone or influenza B alone was 49% (95% CI: -2% to 75%) and 52% (95% CI: 23% to 70%) respectively. Vaccination remains the best protection against influenza.
by DM Skowronski, NZ Janjua, G De Serres, JA Dickinson, A Winter, SM Mahmud, S Sabaiduc, JB Gubbay, H Charest, M Petric, K Fonseca, P Van Caeseele, TL Kwindt, M Krajden, A Eshaghi, Y Li
The 2012/13 influenza season in Canada has been characterised to date by early and moderately severe activity, dominated (90%) by the A(H3N2) subtype. Vaccine effectiveness (VE) was assessed in January 2013 by Canada’s sentinel surveillance network using a test-negative case–control design. Interim adjusted-VE against medically attended laboratory-confirmed influenza A(H3N2) infection was 45% (95% CI: 13–66). Influenza A(H3N2) viruses in Canada are similar to the vaccine, based on haemagglutination inhibition; however, antigenic site mutations are described in the haemagglutinin gene.
Surveillance and outbreak reports
by J Castilla, I Martínez-Baz, V Martínez-Artola, G Reina, F Pozo, M García Cenoz, M Guevara, J Morán, F Irisarri, M Arriazu, E Albéniz, C Ezpeleta, A Barricarte, Primary Health Care Sentinel Network, Network for Influenza Surveillance in Hospitals of Navarre
by RG Pebody, N Andrews, J McMenamin, H Durnall, J Ellis, CI Thompson, C Robertson, S Cottrell, B Smyth, M Zambon, C Moore, DM Fleming, JM Watson
by E Kissling, M Valenciano, A Larrauri, B Oroszi, JM Cohen, B Nunes, D Pitigoi, C Rizzo, J Rebolledo, I Paradowska-Stankiewicz, S Jiménez-Jorge, JK Horváth, I Daviaud, R Guiomar, G Necula, A Bella, J O’Donnell, M Głuchowska, BC Ciancio, A Nicoll, A Moren
The CIDRAP report (which I highly recommend), puts this avalanche of VE data into perspective:
Studies: Flu vaccine effectiveness waned over 2011-12 season
Robert Roos
News Editor
Jan 31, 2013 (CIDRAP News) – It's been more or less an article of faith that influenza vaccination in the fall will protect a person through the winter flu season, but three studies published today in Eurosurveillance are challenging that view.
All three studies suggest that during the 2011-12 flu season, the vaccine provided modest protection at first, but its effectiveness dropped sharply after 3 or 4 months.
As we’ve discussed before, there is a pressing need for better flu vaccines (see CIDRAP: The Need For `Game Changing’ Flu Vaccines) - but until they can be developed - the flu shots we have remain the best preventative action you can take against the flu.
Beyond the vaccine, the CDC also reminds us:
Take everyday preventive actions to stop the spread of germs.
- Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
- Wash your hands often with soap and water. If soap and water are not available, use an alcohol-based hand rub.*
- Avoid touching your eyes, nose and mouth. Germs spread this way.
- Try to avoid close contact with sick people.
- If you are sick with flu–like illness, CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. (Your fever should be gone without the use of a fever-reducing medicine.)
- While sick, limit contact with others as much as possible to keep from infecting them.
