Road to Mecca begins with swine flu shot

>>> of serious damage or injury.

>>> the largest annual gathering in the world is now under way in saudi arabia . as muslims take part in the hajj pilgrimage to mecca. for five days the faithful pray together, eat together and sleep side by side . but this year there's a concern the closeness of the damagering could make it the perfect breedling grunt for the swine flu virous. nbc's jim maceda is in where it could be put in place.

>> reporter: health officials are worrying. pilgrims were encouraged to be fax nated against the h1n1 before arriving in saudi arabia . we receive d vials in cairo. the saudis' front-line of offense is airports where they screen passengers for temperatures. health workers check vaccination certificates. anyone chethey check are sent straight to the hospital.

>> he's doing well.

>> reporter: 25 fully equipped hospitals with a fleet of mobile hyun its are ready to provide free health care . more precautions in mecca. sanitation teams disinfect the marble floors around the great mosque. volunteers hand out facemacks but some are just putting their trust in good.

>> my faith say if it's going to happen here, it doesn't matter to me.

>> reporter: this year's hajj is a pretree dish for the study of the h1n1 virus. data here will be collected for the centers for the dees control in atlanta. for the first time, the cdc has a team working with the saudis watching to see if the virus mutatesing into some more deadly.

>> that is something we watch carefully because we only have a few drugs that we can use and we want to preserve the use of drugs to treat ill people.

>> reporter: so far, fewer than 100 cases of swine flu were detected, and only 4 deaths attributed to the virus. but the real toll won't be another until hajj is over and the pilgrims are back in their home country. thomas feld, nbc news, mecca.