Demand for swine flu vaccines below original forecasts is threatening to slow the growth in predicted revenues for four of Europe’s leading pharmaceuticals companies.

Academic studies in recent weeks have shown that most people require a single dose of vaccine in order to acquire protection, compared with the two doses originally believed necessary and used in orders by governments, including the UK.

Separately, public suspicion of the perceived risks of vaccines at a time when the impact of swine flu is far less than previously feared is also discouraging the use of those vaccines already delivered.

The fall in demand may affect sales by the leading flu vaccine suppliers, which are all based in Europe – GlaxoSmithKline, Sanofi-Aventis, Novartis and AstraZeneca.

Countries including Spain and Germany are attempting to renegotiate their contracts with suppliers.

In a research note, Morgan Stanley, the investment bank, said the efforts to return vaccines could create “near-term earnings per share risk” at the four companies, with sales cut by 15 per cent in Spain and Germany.

It estimated previously that GSK stood to gain total sales this year and next from swine flu vaccines of £2.2bn, Sanofi-Aventis of €750m and Novartis of €600m.

The contracts signed between governments and suppliers vary widely, although many are believed not to have anticipated renegotiations in the event of lower demand. The contracts were agreed at a time when forecasts suggested supplies would be substantially lower than demand.

One option for countries unable to renegotiate with suppliers would be to re-sell vaccines to other governments without vaccine stocks, or to donate them to poorer countries via the World Health Organisation. They could also stockpile them for future use.

However, GSK’s vaccine sold in Europe, and produced in its Dresden factory, has yet to be approved by the World Health Organisation, although its US supplies, made in Canada, have been authorised. This could create complications for any European donations made to other countries.

GSK has said it has received pandemic vaccine orders to date of 440m doses from more than 40 countries, with 107m so far shipped. Sanofi-Aventis has said it has orders for 250m doses, while AstraZeneca has delivered 21m of the 40m doses ordered by its sole purchaser, the US government.

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