Editorial: Silent spread of H7N9

With the continued spread of influenza A(H7N9) virus to 127 people in China and a concomitant increase in the number of deaths (26), the outbreak has confirmed what the World Health Organisation had earlier noted — H7N9 is “definitely one of the most lethal influenza viruses we have seen so far.” Nineteen people infected with the virus in a short span of a week is proof that the virus is gaining momentum in jumping from its animal host to humans. Surprisingly, the virus does not exhibit the same virulence in those infected. Twenty-six people have recovered and a few asymptomatic cases have also been found. Though recovery from infection is good news, the presence of asymptomatic cases does not augur well. Scientists are yet to confirm with certainty the host that harbours the virus, and the infected birds show no visible signs of illness. Though the virus has been detected in a small number of poultry and a link found between poultry and four patients who had occupational exposure to poultry, over 20 per cent of those infected have had no contact with poultry. While sustained human-to-human transmission has not been seen, there have been proven clusters of such a spread. A May 1 paper in The Lancet clearly brings out the complexity of H7N9’s origin. According to the study, the virus has originated from “multiple reassortment events” and might have evolved from “at least four origins” involving migratory birds and poultry, and has evolved to at least “two different lineages.”

The only silver lining in the latest episode is the willingness of China to readily share live virus samples with WHO and other laboratories and upload the genetic sequence of the virus to the Global Initiative on Sharing All Influenza Data (GISAID) database the very same day the first human case of infection was reported. This is a huge leap forward compared with its near secrecy during the 2002 SARS outbreak. But the darker side of data sharing has already reared its ugly head. According to Nature, Novartis in Basel and the J. Craig Venter Institute in Rockville, Maryland planned to use the data to make H7N9 vaccines but without informing or involving the Chinese team. Though the issue seems to have been ironed out, the episode brings back memories of what Indonesia faced following the H5N1 outbreak. In 2007, the country refused to share samples after an Australian drug company developed a vaccine using the Indonesian strain but without their knowledge or consent. This episode confirms that GISAID, launched in 2008 to bring in more transparency and engagement, is struggling to fully deliver on its promise.

Published in The Hindu on May 3, 2013