Swine flu scareSwine flu vaccine is not going to be ready for a while yet

A vaccine against the Mexican swine flu will likely arrive too late for most people, vaccine officials told New Scientist’s Debora MacKenzie. The World Health Organization (WHO) is now considering whether to advise the world’s vaccine makers to switch from ordinary flu vaccine to the Mexican H1N1. WHO is considering officially declaring the swine flu as a pandemic, but even if it does, vaccine will arrive too late for many.

Studies so far suggest that H1N1 has been only slightly more lethal than ordinary flu. The difference is that regular seasonal flu hits the very elderly hardest, but the current swine flu virus affects the young. There are fears that it could become worse in subsequent waves as in previous pandemics. “We are starting experiments to see what changes make this virus more dangerous,” says Ab Osterhaus of Erasmus University in Rotterdam, the Netherlands.

MacKenzie writes that vaccine makers are left with a dilemma. “If we make ordinary vaccine and the pandemic comes instead, we will be blamed,” says Norbert Hehme, chair of the industry’s flu vaccine task force. “If we make pandemic vaccine and get ordinary flu, we will have a shortage of ordinary vaccine, so we will also be blamed.”

The industry will thus not switch to H1N1 vaccine without WHO approval and the go-ahead from governments with vaccine contracts, says Bram Palache, chair of the European Vaccine Manufacturers (EVM) flu vaccine group. Even if that happens soon, there will be none before September because of the time needed to produce it.

First companies need “seed” virus containing two genes for antigens, or surface proteins, from H1N1 and the rest from a standard vaccine strain. That was expected this week from labs working with the WHO. “We were told Monday we won’t get it till the end of May. I don’t know why,” says Luc Hessel of the EVM.

MacKenzie writes that it then takes three weeks to make enough seed to grow in eggs — or at one Czech plant, in cell culture. None of the modern cell-culture plants planned in response to bird flu have been built — they would have made it possible to produce much more vaccine. Last year, the Belgian firm Solvay canceled one planned for the US, citing insufficient demand for ordinary flu vaccine. “Potential demand for pandemic vaccine cannot justify the investment,” Palache says. “It only takes three days to grow the virus in eggs, but weeks for testing and formulating,” Hessel adds. That means no vaccine until September, and no real quantities until October. Then countries have to administer millions of doses, which take weeks to take effect. In 1918, the worst wave of the pandemic hit in September.

It takes weeks for testing and formulating. That means no vaccine before September

The first to get pandemic vaccine will be the 15 countries who have pre-ordered a total of about 250 million doses. “We can’t say how long making them will take,” Palache warns. It partly depends on how much virus is needed per dose. In theory, countries that place new orders now might get vaccine in November. In 1918, the autumn wave was nearly over by then. The 15 countries with advance purchase agreements include Canada and Australia, which have vaccine plants, New Zealand, and 12 European countries including the United Kingdom. Europe has 70 per cent of the world’s manufacturing capacity. Other countries, including Japan and China, plan to produce their own.

The United States has one vaccine plant, owned by French drug giant Sanofi-Aventis, which could in theory produce enough for the U.S. population. However, the US has no advance purchase order in place.