Monday, September 2, 2013

Nonsense: 1. Vaccinate for flu now 2. Protection starts decreasing about two weeks after a shot 3. Flu almost never appears before December / NBC News

Vaccinate your children for flu asap, say the experts.  From NBC News:
"Get your kids their flu vaccines now, pediatricians advise."
“With the exception of children less than 6 months of age, everybody should go out and get their influenza vaccine as soon as the influenza vaccines are available,” Dr. Michael Brady of Nationwide Children's Hospital and chairman of the Committee on Infectious Diseases for the Academy told NBC News...
It also takes a week or so for the flu vaccine to take effect and provide full protection.
“Most time, flu in the U.S. peaks in January, February, sometimes into March,” Brady said.  “If people go get their vaccines as soon as their provider has them available, they should feel comfortable that they'll have protection for the whole flu season.” 

There are two potential problems with getting flu shots early.  First, vaccine protection decreases rapidly and those who are older or have less robust immune systems may have lost protection before the flu appears.  

Second, frequently the vaccine does not protect against the strains that cause disease each season.  But until flu appears, we don't know if the vaccine will protect.  By waiting to vaccinate until late fall, you will know whether the flu shot is likely to provide any benefit at all against that year's flu strains.


Hal said...

First, vaccine protection decreases rapidly and those who are older or have less robust immune systems may have lost protection before the flu appears.

Can you cite reference for this claim?

Meryl Nass, M.D. said...

Yes, there have been a number of such studies over the years. There was another just out this week I ran across.

Meryl Nass, M.D. said...

Here is another 2013 study in which vaccinated individuals had no protection from flu late in the season.

Euro Surveill. 2013 Jan 31;18(5). pii: 20390.
Low and decreasing vaccine effectiveness against influenza A(H3) in 2011/12 among vaccination target groups in Europe: results from the I-MOVE multicentre case-control study.
Kissling E, Valenciano M, Larrauri A, Oroszi B, Cohen JM, Nunes B, Pitigoi D, Rizzo C, Rebolledo J, Paradowska-Stankiewicz I, Jiménez-Jorge S, Horváth JK, Daviaud I, Guiomar R, Necula G, Bella A, O'Donnell J, Głuchowska M, Ciancio BC, Nicoll A, Moren A.
EpiConcept, Paris, France.
Within the Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) project we conducted a multicentre case–control study in eight European Union (EU) Member States to estimate the 2011/12 influenza vaccine effectiveness against medically attended influenza-like illness (ILI) laboratory-confirmed as influenza A(H3) among the vaccination target groups. Practitioners systematically selected ILI / acute respiratory infection patients to swab within seven days of symptom onset. We restricted the study population to those meeting the EU ILI case definition and compared influenza A(H3) positive to influenza laboratory-negative patients. We used logistic regression with study site as fixed effect and calculated adjusted influenza vaccine effectiveness (IVE), controlling for potential confounders (age group, sex, month of symptom onset, chronic diseases and related hospitalisations, number of practitioner visits in the previous year). Adjusted IVE was 25% (95% confidence intervals (CI): -6 to 47) among all ages (n=1,014), 63% (95% CI: 26 to 82) in adults aged between 15 and 59 years and 15% (95% CI: -33 to 46) among those aged 60 years and above. Adjusted IVE was 38% (95%CI: -8 to 65) in the early influenza season (up to week 6 of 2012) and -1% (95% CI: -60 to 37) in the late phase. The results suggested a low adjusted IVE in 2011/12. The lower IVE in the late season could be due to virus changes through the season or waning immunity. Virological surveillance should be enhanced to quantify change over time and understand its relation with duration of immunological protection. Seasonal influenza vaccines should be improved to achieve acceptable levels of protection.