Marc Pelletier of Futures in Biotech and Vincent Racaniello of This Week in Virology discussed the current influenza situation in a live video broadcast hosted on the TWiT network this past Friday. We are very grateful to Leo LaPorte and the TWiT network for providing the video feed for the show. The audio was recorded and will be posted as an upcoming episode of Futures in Biotech. Many thanks to Colleen and Dane for their great help with the session. Above is a screen capture taken at the end of the show. Colleen is at the microphone and Marc and Vincent can be seen on two monitors of the skypesaurus. It was amazing to be part of a TWiT production, especially after having watched so many of them. The video and audio were excellent and I enjoyed seeing the technical underpinnings of TWiT live. This live video solution will, in my opinion, revolutionize science teaching.
A video of the entire session at On-Demand TWiT Video. Look for ‘Futures in Biotech 42’; you might have to scroll down the page a bit as other videos are added.
Thank you for a comprehensive overview of the issue. However I was somewhat confused by your explanation of the vaccine development process. If the decision is made in March why is it based on the strains circulating in the Southern Hemisphere? At this point the flu season there had not started yet. I got the impression that Marc also did not understand but did not pursue it.
Sorry I did not make that clearer. Here is the proper explanation from
the CDC. Strain information from the southern hemisphere is used
because those strains will make their way north. Even though in the
beginning of the year the flu season has not yet begun in the south,
some strains circulate all year and the identity of these are
informative.
The viruses used in making flu vaccine are chosen each year based on
information gathered over the previous year about the strains of flu
viruses that are infecting humans and how they are changing.
Circulating influenza strains and information on disease trends are
gathered by 122 national influenza centers in 94 countries and the
viruses and other data are further tested and combined data are
analyzed by the four World Health Organization (WHO) Collaborating
Centers for Reference and Research on Influenza located at the Centers
for Disease Control and Prevention (CDC) in Atlanta; London, United
Kingdom; Melbourne, Australia; and Tokyo, Japan. Based on this
information, experts forecast which viruses are likely to circulate
the following season and WHO recommends specific virus strains that
can be used to make vaccines to protect against them. For vaccines
being made for the Northern Hemisphere, the recommendation is made by
WHO in February each year. For vaccines being made for the Southern
Hemisphere, the recommendation is made by WHO in September. Each
country then can use the recommendations made by WHO to assist with
national decisions about what viruses to use in influenza vaccines for
their country. In the U.S., an advisory committee convened by the Food
and Drug Administration (FDA) makes the final decision about vaccine
strains in February. Manufacturers grow vaccine strains based on these
recommendations; but they often begin the production process as early
as January based on their assessment of which strains will be chosen
for the vaccine.
Thank you. So if I get it right, the idea is that if you want to identify strains that will become widespread six months from now, you should be looking at new strains in the Southern hemisphere, which are not very active yet, but can be expected to circulate widely by the end of the Southern flu season. There would not be much point to look at the current epidemic strains in the Northern Hemisphere because much of the population already has immunity against them.
Or would it be more accurate to say that whatever strains are present in the Southern Hemisphere in the beginning of their flue season will proliferate and have a good chance to jump back to the North later, even if it is the same strain that we already had last year? How significant would the herd immunity typically be at the end of a flu season and would it typically prevent active circulation of the same strain next year?
Your statement is accurate. Herd immunity depends upon
cross-reactivity of antibodies in the immune population with the
virus. Therefore, if the virus had undergone antigenic drift in the
southern hemisphere, then herd immunity in the north would be less
protective.
Your statement is accurate. Herd immunity depends upon
cross-reactivity of antibodies in the immune population with the
virus. Therefore, if the virus had undergone antigenic drift in the
southern hemisphere, then herd immunity in the north would be less
protective.