In an attempt to prevent an outbreak of measles on campus, University Health Services has reinnoculated 800 undergraduates this fall.

The move comes in response to concerns that college-age students who were first immunized as babies may still be susceptible to the highly contagious measles virus.

Over the summer, UHS mailed students letters asking them to get a measles vaccination at home or upon arriving at school.

Dr. Charles Weingarten, chief of medicine at UHS, said that more than 800 of the 1200 to 1500 students who had incomplete immunization records have been vaccinated since the beginning of the school year, with as many as 80 students receiving the shot on any given day.

Harvard is not alone in its concern over a possible measles outbreak.

In 1989, the American Academy of Pediatrics recommended that college age students receive a second round of measles vaccinations. The State Department of Public Health and Board of Public Education issued a similar recommendation last January.

And starting with the next school year, the state may require colleges to innoculate their students before they can register, said Mary Ann Hart, a spokesperson for the Department of Public Health.

All those who received a measles shot before they were 15 months of age must receive a second dose because "blocking maternal antibodies prevented them from mounting their own antibodies from the vaccine," said Dr. Susan M. Lett, medical director of the immunization program at the Department of Public Health.

Even those who were immunized after 15 months of age need a new shot, doctors said, because a small percentage of people do not respond to the first dose of measles innoculation.

Prior to 1980, 90 to 95 percent of the measles innoculations were effective. That is considered sufficient for other viruses, "but measles needs a higher percentage of herd immunity because it is so infectious," said Lett.

"Measles is so contagious that you can catch it from entering a room where an infectious person has been up to two hours after they have left the room," she said.