Google on Monday launched Google Health, a long-anticipated medical records service letting US users store and manage their health care information online.
The offering raises privacy concerns and draws yet another battle line between Internet search king Google and global software giant Microsoft, which began offering a similar HealthVault service in October.
"It isn't surprising both sides are going after it," Silicon Valley analyst Rob Enderle told AFP.
He said the service was likely to strongly appeal to "Baby Boomers" -- the generation of Americans born between the late 1940s and early 1960s.
"Health care is not just lucrative -- you are solving a problem critical to an aging group of Boomers. There are public relations and business benefits to it," he said.
Google said it built a secure computer platform separate from its search system to host medical records as part of an emphasis on keeping the health information protected.
"It is our highest level of security."
Privacy advocates however, seek proof that online medical information will be safe from tampering or snooping, possibly from insurance companies or employers out to reduce liabilities by shunning those with health issues.
"It's the Wild West online," said Deborah Peel, a psychiatrist who founded the nonprofit advocacy group PatientPrivacyRights.org. "The risks are massive."
She said Microsoft consulted her group while designing HealthVault and agreed to routine privacy audits, the first of which is to be completed in June.
Google executives said pains were taken to build a system that will protect people's medical records while providing them access from wherever they might want it.
"No Google Health users should expect to find their health information as search results on Google," product manager Roni Zeiger said.
Google Health has links to pharmacies, clinics and diagnostic labs. The service is free and enables people to have electronic copies of information such as prescriptions, lab test results, hospital stays, and medical conditions stored on Google computers.
Users of the service dictate how the information is shared.
"Google, on your behalf, is storing a copy of your records," Zeiger said. "This is a user controlled database that Google is hosting."
Google said it will mine anonymous trend data along the lines of what percentage of people with diabetes using Google Health report getting flu shots.
Google search boxes are on Health pages and targeted advertising is displayed with query results, according to Zeiger.
But Jeff Chester, executive director of the Center for Digital Democracy, said targeting health searches with ads was tantamount to tracking users' medical issues for advertisers.
"There is no question in my mind that at the end of the day this is about marketing pharmacology and health related products to consumers," he told AFP.
"Google, Microsoft and others see dollar signs in your diagnosis."
Google said it built protected online connections with a host of major US medical service providers and is open to working with other health care outlets interested in crafting software to join the network.
Dean Ornish, a California professor of medicine and founder of the nonprofit Preventive Medicine Research Institute, enthused about the new service.
"I'm excited by this because it really empowers people with getting more control over their information," said Ornish, who is on a medical advisory board working with Google on health.
People can link heart monitors to Google Health so vital statistics can be fed to a heart attack assessment services online.
A "virtual pillbox" will also automatically send alerts to people's mobile telephones, reminding them when it is time to take medicines.