Do all the affected areas have good medical care?
Volunteer organisations like the Red Cross have been working flat out, but the disaster covers such a huge area that they have been spread thin. For example, people in Staten Island, where 19 have died as a result of the storm, say they’re being ignored .

People most at risk now include those who need regular medical care, such as kidney dialysis, or those who suffer an emergency such as a heart attack. Transport is sparse, and some hospitals are stretched or shut.

This seems to be because vital equipment was located in basements that flooded, despite the publicity over a similar loss of back-up power at hospitals in New Orleans after Hurricane Katrina in 2005. New York University’s Langone Medical Center lost one back-up generator, then the back-up to that one, because even though one of the generators was located prudently on a roof, its fuel pump was not.

What is the biggest health threat after a disaster like this?
The biggest is also one of the most overlooked, says Bruce Altevogt of the US Institute of Medicine’s forum on medical preparedness for catastrophe : mental health.

“Research shows 30 to 40 per cent of disaster victims are at risk of a new mental disorder”, especially depression and post-traumatic stress disorder, says Merritt Schreiber of the University of California at Irvine. Both can be debilitating, even fatal.

Schreiber has developed a tool for spotting those at risk early. Red Cross workers helping people displaced by Sandy are wearing cards around their necks, with a checklist developed for his PsySTART mental health triage system . “It doesn’t help to ask people how they’re feeling,” says Schreiber, because right after a disaster, people who will bounce back feel as upset as those who will suffer long-term problems.

If people have experienced certain trials – separation from family, being trapped, severe panic or loss of home, for example – they are likely to need help.

Those people are identified by the volunteers and then earmarked for attention from a mental-health professional. Work with people who survived the 2005 London bombings showed that a few hours of cognitive therapy – which includes emotional and relaxation exercises and talking through specific anxieties – could prevent long-term psychological problems. “I want to get those people earlier through triage,” says Schreiber.

What about all the rats in the New York subway?
Many New Yorkers think the notorious rodents were killed when floodwaters rushed into tunnels. Richard Ostfeld , a disease ecologist and rodent specialist at the Cary Institute of Ecosystem Studies in Millbrook, New York, suspects that many of them survived by swimming and climbing.

That could be a problem. Between 30 and 60 per cent of the rats in any group carry a hantavirus called Seoul, similar to the one that struck Yosemite park in California earlier this year. When groups escape their flooded tunnels and encounter strange rats, they will fight – this spreads the virus and increases the number of rats infected. “Higher prevalence in rats will mean higher transmission probabilities to people. So, an increase in human risk is plausible from the basic biology,” says Ostfeld.

Moreover, with people dumping all that spoiled food from their darkened refrigerators, there might soon be many more rats in New York, rather than fewer. Clean-up crews would be advised to wear face-masks.