Vincent Racaniello

"The 'normal' influenza vaccine, or the seasonal vaccine, consists of three different viruses: seasonal H1N1 and H3N2, and an influenza B virus strain. It is made in the same way as the 2009 H1N1 vaccine; the only difference is that vaccine contains only one virus, the pandemic H1N1 strain. Side effects such as swelling at the injection site, fever, and rashes were reported in the clinical trial and are not unexpected when the vaccine is used in the general population. Clinical trials cannot prove that a vaccine is 100% safe; but they can provide information on commonly occurring side effects." - Vincent Racaniello

"This information is incorrect. The vast majority of the influenza vaccine is produced in chicken eggs. The virus is purified and disrupted; the vaccine has trace amounts of egg proteins, detergent, and formaldehyde, but none of the other ingredients which you list. The vaccine has been produced in this way for over 40 years and has an excellent safety profile." - Vincent Racaniello

"There are amino acid changes in the influenza HA that are known to allow cleavage by cellular proteases that are in many tissues, ie not restricted to the respiratory tract. But no 2009 H1N1 isolate has these mutations. As far as I know this strain is not neurotropic." - Vincent Racaniello

"That's never been shown to be a consequence of original antigenic sin. If immunization is against antigenically distinct strains one would simply expect that the new strain would not be recognized by the memory response. No reason to believe infection with the novel strain would be worse." - Vincent Racaniello

"Thanks for that letter. Interesting that pigs are discussed as possible vectors for influenza. It is my understanding that influenza went into pigs for the first time in 1918, and wasn't known before that." - Vincent Racaniello

"The data for that statement are included in the Science paper referenced at the bottom of the post." - Vincent Racaniello

"Thank you for picking up those errors; I've corrected them. For some reason, when it comes to alpha(2,3) and alpha(2,6) preferences, I always mix them up. I just did it last week when I lectured medical students. One emailed me afterwards to let me know about it. At least I know some people are listening!" - Vincent Racaniello

"Maybe after they read this post they will realize that the mutation doesn't matter." - Vincent Racaniello

"I haven't tried mixing virus with ZnCl2 before plating, but it's worth a try. I'll do it next week." - Vincent Racaniello

"It's just the first three letters of the alphabet." - Vincent Racaniello

"As far as I'm concerned, viruses are not alive - but many disagree with me and their arguments are cogent. It's one of those questions with no single answer and which can be debated forever. That's evident from the poll results." - Vincent Racaniello

"That would depend on your definition of life! According to some, computer viruses would be included as living. Which means that we have to be careful about how we define life. In my view neither viruses with nucleic acids, nor computer viruses, are living." - Vincent Racaniello

"AS03 adjuvant has been tested together with the H5N1 vaccine in 39,000 individuals and has an acceptable safety profile. Testing with an H1N1 component (Arepanrix) is ongoing; limited data are available at Canada Health, http://bit.ly/8bbIhK and in the product leaflet: http://bit.ly/4uxYPE." - Vincent Racaniello

"Fabulous! I should have included that as a possible answer to the survey question." - Vincent Racaniello

"Yes, the current vaccine will definitely protect even against a H1N1 strain resistant to Tamiflu. I'm shocked that the CDC rep didn't know that." - Vincent Racaniello

"That is a great question which no one has ever been able to answer. It's been seen before. For example, in 1957, when the H2N2 pandemic strain emerged, the H1N1 strains that had been circulating since 1918 disappeared. In 1968, when the pandemic H3N2 strain emerged, the H2N2 strains went away. One idea is 'antigenic sin', which says that when the new strain emerges, it stimulates a strong memory response to influenza viruses that have previously infected the host. But it's not clear if that explains everything." - Vincent Racaniello

"The H1N1 strain is not going to escape the vaccine this season. It might drift sufficiently next year so that another vaccine is needed; but the seasonal flu strains (which is what the N1N1 strain will soon become) change every few years anyway. There is ZERO evidence that the 1918 influenza virus mutated to a more lethal form with subsequent waves of infection. This is a hypothesis for which there is not evidence. So is the cytokine storm pathogenesis of severe influenza disease an hypothesis. The vaccine is protective and safe and should be the main means of preventing infection." - Vincent Racaniello

"It is possible that some 2009 H1N1 virus was circulating early in 2009; in fact sequence analysis suggests that the virus originated towards the end of 2008. However I believe it's likely the strain would have been detected. Even though many strains are not subtyped, enough of the swine-origin virus would have cropped up as 'untypable' to warrant further analysis. Which is what happened in California and Texas in April 2009." - Vincent Racaniello