Washington, Aug 13 - One of the worst hit nations, the US is gearing up for a second wave of the swine flu virus fearing a new attack that could lead to major disruptions in schools, workplaces and hospitals within weeks.

With all 50 states and the capital city of Washington DC hit by mid-June, the US has seen over 6,500 hospitalisations and 436 deaths to date. But the epidemic has since been contained and there is little public anxiety and few visible signs of panic.

However, the number of cases could increase rapidly as soon as schools begin to reopen in the next few weeks and could accelerate further as cooler, drier temperatures return, possibly peaking in October, officials fear.

But unlike last spring when the first wave hit the US leading to temporary closure of hundreds of schools across the country, federal, state and local officials are planning a more measured response.

Health officials in various states say they have been preparing all summer for the swine flu's return, with intensified monitoring and plans to distribute vaccine and antiviral drugs and have set up special clinics to treat and vaccinate patients if necessary.

'There's a lot of moving parts to this,' says Joseph S. Bresee, who heads the US Centers for Disease Control and Prevention's (CDC) influenza epidemiology and prevention branch. 'Hopefully we won't have a panic, but instead we'll have the appropriate level of concern and response.'

The Obama administration has been updating recommendations for when to close schools, what parents should do if their children get sick, how doctors should care for patients and how businesses should respond to large-scale absences.

Updated federal guidelines for schools released Aug 7 by the CDC and the US Department of Education discourage schools from closing even if the H1N1 virus, or swine flu, strikes.

They suggest that schools not close unless a mass number of students have confirmed swine flu cases or too many staff members become ill.