How long after you have taken Tamiflu is it still effective?

Can you get the H1N1 flu after you have taken tamiflu?

• Answer:

  In short - yes, but some explanation is warranted. In the way the question is worded, the asker is either currently on tamiflu, or has taken tamiflu in the past but is no longer currently taking it. If the asker has taken tamiflu in the past but is not currently taking it, it won't serve to prevent them from becoming infected with the novel h1n1 (or any other flu virus they haven't established immunity to. Antivirals function somewhat similarly to antibiotics - they acts to inhibit the pathogen from successfully completing its reproductive life-cycle. The difference with oseltamivir and zanamivir (aka Tamiflu and Relenza) is that they bind specifically to the active sites in certain types of flu virus. Neither one will act as any sort of 'immunization' to prevent future infections. It simply limits the virus from making more of itself once you have contracted it. If one is currently taking the drug, it may prevent contraction from becoming a full-blown infection, or limit the severity, but it won't cause the body to recognize the virus any faster, it just gives the immune system more time to respond. In one recent study published in Japan (where Tamiflu is widely used), they did have at least one case of H1N1 flu in someone who was taking the drug as a prophylactic (preventative) measure. However, they note that those taking Tamiflu in close contact with confirmed cases of the flu did not develop severe illnesss. Here is a link to a pdf of the study for further reading: http://www.eurosurveillance.org/images/dynamic/EE/V14N35/art19320.pdf Regards, Perry Arellano-Jones