Deadly H7N9 influenza virus: a pandemic in the making or a warning lesson?
Robert A Lamb
Am J Respir Crit Care Med. 2013 Jul 1;188(1):1-2. doi: 10.1164/rccm.201305-0914ED.
This is a clear editorial providing a short description of the mutations encoded by the H7N9 viruses infecting humans. It closes with “it cannot be predicted whether avian/human H7N9 influenza viruses will remain a zoonosis in China or become a global pandemic with dire consequences.”
This is in keeping with other papers discussing the great difficulty in predicting influenza pandemics. Bob Lamb has published more than 140 papers on influenza and its viruses.
Sunday, July 21, 2013
Friday, June 21, 2013
June 21, 2013
H5N1 hybrid viruses bearing 2009/H1N1 virus genes transmit in guinea pigs by respiratory droplet.
Zhang Y1, Zhang Q, Kong H, Jiang Y, Gao Y, Deng G, Shi J, Tian G, Liu L, Liu J, Guan Y, Bu Z, Chen H.
Science. 2013 Jun 21;340(6139):1459-63. doi: 10.1126/science.1229455. Epub 2013 May 2.
Comment to be posted.
Zhang Y1, Zhang Q, Kong H, Jiang Y, Gao Y, Deng G, Shi J, Tian G, Liu L, Liu J, Guan Y, Bu Z, Chen H.
Science. 2013 Jun 21;340(6139):1459-63. doi: 10.1126/science.1229455. Epub 2013 May 2.
Comment to be posted.
Thursday, January 31, 2013
Sample size considerations for one-to-one animal transmission studies of the influenza A viruses.
Nishiura H, Yen H-L, Cowling BJ (2013)
PLoS ONE 8(1): e55358. doi:10.1371/journal.pone.0055358
A very detailed scientific analysis of the number of ferrets needed to generate statistically significant results.
“The most important caveat in the present study in relation to the common practice is that n = 3 is not enough to show a significant difference as well as Ro>1 for one-sample comparison while it can demonstrate Ro>0. Moreover, comparing a group with n = 3 against a reference group with the same sample size does not allow researchers to demonstrate any significant difference in the transmissibility between two sample groups. If two samples have to be compared, n = 4 would be regarded as minimum, and moreover, k = n for n = 4 and k = n or k= n-1 for n = 5, respectively, would have to be required along with the absence of infected pairs in the control group.”
More prosaically, this says that in an influenza A virus transmission experiment the use of three pairs of ferrets (infected donor and uninfected receiver animal, n = 3) is enough to demonstrate transmission (Ro>0) but not to know whether the virus would spread (Ro>1). If a GOF flu virus is to be compared to a another, say a human influenza virus, a minimum of four pairs of ferrets (n = 4) with all four receiver ferrets becoming infected (k = 4, and hence k = n), would be necessary. If five ferrets were used (n = 5) then a significant result would be obtained if 4 of 5 receiver ferrets were infected (k = n-1 for n = 5).
As n=2 or 3 in the Fouchier and Kawaoka experiments little can be deduced except to say that the viruses were transmitted. Nothing can be said about their potential to spread. In short the conclusions are qualitative.
Nishiura H, Yen H-L, Cowling BJ (2013)
PLoS ONE 8(1): e55358. doi:10.1371/journal.pone.0055358
A very detailed scientific analysis of the number of ferrets needed to generate statistically significant results.
“The most important caveat in the present study in relation to the common practice is that n = 3 is not enough to show a significant difference as well as Ro>1 for one-sample comparison while it can demonstrate Ro>0. Moreover, comparing a group with n = 3 against a reference group with the same sample size does not allow researchers to demonstrate any significant difference in the transmissibility between two sample groups. If two samples have to be compared, n = 4 would be regarded as minimum, and moreover, k = n for n = 4 and k = n or k= n-1 for n = 5, respectively, would have to be required along with the absence of infected pairs in the control group.”
More prosaically, this says that in an influenza A virus transmission experiment the use of three pairs of ferrets (infected donor and uninfected receiver animal, n = 3) is enough to demonstrate transmission (Ro>0) but not to know whether the virus would spread (Ro>1). If a GOF flu virus is to be compared to a another, say a human influenza virus, a minimum of four pairs of ferrets (n = 4) with all four receiver ferrets becoming infected (k = 4, and hence k = n), would be necessary. If five ferrets were used (n = 5) then a significant result would be obtained if 4 of 5 receiver ferrets were infected (k = n-1 for n = 5).
As n=2 or 3 in the Fouchier and Kawaoka experiments little can be deduced except to say that the viruses were transmitted. Nothing can be said about their potential to spread. In short the conclusions are qualitative.
Thursday, January 3, 2013
January 3, 2013
Safety survey reveals lab risks
Van Noorden R.
Nature. 2013 Jan 3;493(7430):9-10. doi: 10.1038/493009a.
The study, which was partly financed by Nature, shows that scientists are overconfident and systematically underestimate risk. This is why scientists need help form outside in assessing risk.
Van Noorden R.
Nature. 2013 Jan 3;493(7430):9-10. doi: 10.1038/493009a.
The study, which was partly financed by Nature, shows that scientists are overconfident and systematically underestimate risk. This is why scientists need help form outside in assessing risk.
Saturday, December 22, 2012
June 7, 2012
Science versus spin: how Ron Fouchier and other
scientists miscommunicated about the bioengineered bird flu controversy
For a lucid history of the early phase of the GOF H5N1 flu virus see
the story by Peter Sandman, a risk communicator. The contradictions between the
early and late versions of the “Fouchier” experiment by Fouchier himself are
indeed worrying and highly irregular. This is not representative of what
happens in the vast majority of labs.
Friday, June 22, 2012
June 22, 2012
Airborne transmission of influenza A/H5N1 virus between ferrets.
Herfst S1, Schrauwen EJ, Linster M, Chutinimitkul S, de Wit E, Munster VJ, Sorrell EM, Bestebroer TM, Burke DF, Smith DJ, Rimmelzwaan GF, Osterhaus AD, Fouchier RA.
Comment to be posted.
Herfst S1, Schrauwen EJ, Linster M, Chutinimitkul S, de Wit E, Munster VJ, Sorrell EM, Bestebroer TM, Burke DF, Smith DJ, Rimmelzwaan GF, Osterhaus AD, Fouchier RA.
Comment to be posted.
Wednesday, May 2, 2012
May 2, 2012
Experimental adaptation of an influenza H5 HA confers respiratory droplet transmission to a reassortant H5 HA/H1N1 virus in ferrets
Imai M1, Watanabe T, Hatta M, Das SC, Ozawa M, Shinya K, Zhong G, Hanson A, Katsura H, Watanabe S, Li C, Kawakami E, Yamada S, Kiso M, Suzuki Y, Maher EA, Neumann G, Kawaoka Y.
Comment to be posted.
Imai M1, Watanabe T, Hatta M, Das SC, Ozawa M, Shinya K, Zhong G, Hanson A, Katsura H, Watanabe S, Li C, Kawakami E, Yamada S, Kiso M, Suzuki Y, Maher EA, Neumann G, Kawaoka Y.
Comment to be posted.
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