GSK announces big jump in swine flu vaccine orders

GlaxoSmithKline (GSK) says total orders for its H1N1 adjuvanted vaccine have reached 291 million doses and are set to rise.

In addition to orders for 195 million doses taken on July 22, GSK has received a further nine government contracts for an additional 96 million doses of its vaccine.

GSK did not put a value on the new orders but noted previously announced contracts with the US government to supply pandemic products worth US$250m.

First supplies of the vaccine will be available to governments from September, with delivery expected in the second half of 2009 and early 2010.

To ensure the vaccine is available to developing nations, and subject to the yield and existing contractual commitments, GSK has allocated 20% of production at its Canadian manufacturing site to developing countries from early September onwards.

Included within this capacity is GSK's donation of 50 million doses of the H1N1 vaccine to the WHO.

Vaccines supplied direct to developing countries will be priced on a tiered basis.

According to research published in The Annals of Internal Medicine, both GSK's Relenza (zanamivir) and Roche's Tamiflu (oseltamivir) are "highly effective" in preventing flu symptoms.

Many countries have been building up stocks of these two antivirals in case of a pandemic, with a view towards using them for both prevention and as a treatment since vaccination may not be immediately available and could be unsuitable for some patient groups.

Both zanamivir and oseltamivir are neuraminidase inhibitors and the stockpiles seem to rely more heavily on oseltamivir than zanamivir. However, resistance to oseltamivir has been reported, particularly in current A(H1N1) pandemic strains.

Dr Nayer Khazeni of Stanford University in California, US and colleagues set out to evaluate the efficacy and safety of the two products when used as seasonal flu chemoprophylaxis. This involved using the drug for up to four weeks.

They reviewed seven recent trials involving more than 7,000 participants. Three were zanamivir trials and the remainder assessed oseltamivir; none compared the two antivirals.

The research found that chemoprophylaxis reduced the frequency of symptomatic flu by 74% in comparison with a placebo, but it did not reduce the risk of asymptomatic infection.

In terms of flu prevention, the researchers found no significant difference between zanamivir and oseltamivir.

Overall, chemoprophylaxis did not lead to increased side effects, although in comparison with a placebo, oseltamivir gave rise to 48% more nausea and vomiting.

All of the trials studied were industry sponsored. Moreover, they were not powerful enough to detect rare adverse events and only involved essentially adult European or Japanese participants, with normal immune systems. The trials did not involve any participants who had been given live attenuated influenza vaccine.

The researchers have called for the safety of extended-duration zanamivir and oseltamivir chemoprophylaxis in children to be studied.

They would also like to see zanamivir formulations that can be delivered safely and effectively to young children, patients with obstructive lung diseases, and the elderly.

Also published in The Annals of Internal Medicine is a study by Dr Benjamin Cowling and colleagues on the efficacy of masks and hand hygiene in preventing flu virus transmission. If a member of a household has flu, then, provided the other members adopt a mask and hand hygiene strategy within 36 hours, transmission to other household members is reduced.

This study, carried out in Hong Kong, involved 407 patients with flu symptoms who tested positive for influenza A or B virus and 794 household members in 259 households.

The households were randomised in three groups. In the control group, comprising 134 households, prevention only involved lifestyle education, in 136 households prevention involved hand hygiene and in 137 households prevention systematically involved both masks and hand hygiene.

Hand hygiene, with or without use of masks seemed to reduce influenza transmission but the differences in transmission compared with the control group were "not statistically significant".

However, in the 154 households in which interventions were implemented within 36 hours of symptom onset in the index patient, transmission of reverse transcription polymerase chain reaction (RT-PCR)-confirmed infection seemed to be reduced. In this group, hand hygiene and the wearing of masks reduced transmission by 67%.

The findings suggest that non-pharmaceutical interventions are important for the mitigation of pandemic and inter-pandemic influenza.