In light of their findings, Ghazi Kayali of St Jude Children's Research Hospital in Memphis in the US and colleagues there and at Egypt's National Research Center in Giza recommend that the H5N1 prevention and control strategy in Egypt be updated and reinforced. Special consideration should be given to the vaccination strategy, they say, and the use of vaccines based on currently circulating viruses is advisable.

In a paper published in Poultry Science, they explain that, after emerging in Egypt in 2006, HPAI H5N1 viruses continued to cause outbreaks in Egyptian poultry and sporadic human infections.

The strategy used by Egyptian authorities relied on vaccinating poultry, depopulating infected areas, and increasing awareness and biosecurity levels. Despite these efforts, H5N1 has become endemic and vaccine-escape variants are thought to have emerged even though commercial poultry vaccines were protective in laboratory settings.

The group studied the cross-reactivity of six commercially available H5 poultry vaccines against recent H5N1 Egyptian isolates in a field setting in Egypt. Only one vaccine based on an Egyptian H5N1 virus induced high cross-reactive antibody titres.

The scientists suggest their results may be explained by the fact that the seed viruses in these vaccines are genetically distinct from H5N1 viruses currently circulating in Egypt.

Reference

Kayali G., A. Kandeil, R. El-Shesheny, A.S. Kayed, M.R. Gomaa, M.A. Kutkat, J. Debeauchamp, P.P. Mckenzie, R.G. Webster, R.J. Webby and M.A. Ali. 2013. Do commercial avian influenza H5 vaccines induce cross-reactive antibodies against contemporary H5N1 viruses in Egypt? Poult. Sci. 92(1):114-118. doi: 10.3382/ps.2012-02637

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