PRESIDENT Barack Obama鈥檚 decision last week to label swine flu a national emergency will likely increase demand for a vaccine that is already in short supply. Yet by the time large amounts of vaccine arrive, it may be too late to stop most infections.
On 23 October, Tom Frieden, head of the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, reported that of vaccine. This is not enough even for the country鈥檚 42 million most vulnerable people: pregnant women, people caring for babies, children under 4, front-line healthcare workers and under-18s with medical problems.
By now, the US should have had 120 million doses, according to predictions in July. This estimate was cut to 45 million when it emerged in August that the vaccine virus was growing at half the usual rate. Now even some of those doses have not arrived. Several companies are now using a faster-growing strain to make vaccine, but supplies won鈥檛 arrive for weeks.
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A by Shelly Towers and Zhilan Feng at Purdue University in West Lafayette, Indiana, shows that this will be too late to stop the majority of infections. Their model indicates that with no vaccination, around 25 per cent of people in the US stand to get sick during the current wave, with infections peaking around now. If vaccination was proceeding according to the CDC鈥檚 latest forecast, just 6 per cent of these infections would be prevented 鈥� because vaccination would come too late to protect many people. In fact, vaccine deliveries have been at the low end of the CDC forecast.
鈥淲ith no vaccination, 25 per cent of people in the US stand to get sick during the current wave鈥�
Vaccination is far from pointless, however. At least 2000 lives still stand to be saved, Towers estimates, and people who get the shot now will have at least partial immunity should H1N1 mutate and cause a pandemic wave next spring, she says.
Read more: Swine flu: Eight myths that could endanger your life
