Some US universities are blocking Chinese students from attending summer programmes because of a fear of severe acute respiratory syndrome. Harvard University has also banned them from graduation ceremonies, writes Jon Marcus.
Guests, including alumni, travelling from Sars-affected regions are required to observe a ten-day waiting period after leaving their countries before staying in university housing.
Chinese visitors will need to provide proof that they have completed the waiting period, in the form of airline ticket stubs, passports, or visas.
"This precaution is necessary because viruses are known to spread more readily in living quarters and other enclosed spaces," a Harvard statement said.
Summer-school students at Harvard and other universities will also be required to observe the waiting period. If they have not, they will not be allowed on campus.
Stanford University has emptied an isolated block of student housing to be used to quarantine anyone suspected of having Sars.
While there have been 148 suspected cases in the US, none has been reported at Stanford or Harvard.