The World Health Organization (WHO) said that it was assessing the importance of public health of a mutation of the pandemic H1N1 virus detected in Norway and some other countries.

The WHO has been informed by the Norwegian Institute of Public Health of a mutation of the H1N1 virus found in two patients who have both died. One of them had severe illness.

Apart from Norway, other countries like Brazil, China, Japan, Mexico, Ukraine and the United States have also observed the mutation. The first one was detected in April as per the UN agency.

The statement also added, "The significance of the mutation is being assessed by scientists in the WHO network of influenza laboratories, although further investigation is underway, no evidence currently suggests that these mutations are leading to an unusual increase in the number of H1N1 infections or a greater number of severe or fatal cases."

The studies suggest that the vaccines which are currently available confer protection and the virus with this mutation remains sensitive to the antiviral drugs, oseltamivir and zanamivir.