Google and Microsoft are set to go head to head in the lucrative consumer healthcare market.
More and more medical data is created each year
In October, Microsoft launched HealthVault, a website that allows users to gather, store and share health information online, whilst Google has been talking about similar offerings.
Both companies are keen to get a foothold in health products as more and more people are using the web as a source for health information and advice.
According to a poll by research firm Harris, 71% of US adults use the web to search for health-related information.
"Google is not a doctor, but people come to us with a lot of health information searches," Marissa Mayer of Google recently told a conference in San Francisco.
"There is a big user information need, which we should ultimately fill."
For example, she said, there are an estimated 2 billion X-rays created every year.
Although the company has not revealed firm details of its plans it has suggested that parts of the health service would be integrated with some of its existing online tools.
For example, a special layer on Google Maps could allow people to find local doctors.
In addition, Ms Mayer has said that the company is investigating ways to make health records portable, for example on a password protected keychain device.
"This is a big vision. It's a multiyear process," she said during a brief on-stage appearance. "We are just getting started."
Whilst Google feels its way, Microsoft has pushed ahead with its one-stop health website.
HealthVault allows users to collect all of their health information in one place including information generated by doctors, such as observations, prescriptions and lab results, as well as information from private health plans.
The site allows users to search for specialist information
The free tools, currently offered as a test version, also let users upload data from a range of health devices such as blood glucose monitors, sports watches and blood pressure monitors.
The company has said that the tool puts the control of health records in user's hands as they can choose who they share health information with.
"It could be family, friends and healthcare professionals," says Sean Nolan, Chief Architect of Microsoft's health solutions group.
"But it is up to the users who have access to their information online."
HealthVault also includes an ad-funded and encrypted search application to allow uses to find healthcare articles and health information on the web.
Google offers similar specialist search through its Co-op tool.
But, whereas the Google search just scours existing web content, Microsoft have signed deals with organisations to provide specialist content.
For example, it has licensed content from the US-based Mayo Clinic.
"The well informed patient becomes a better partner with their doctor," says Brooks Edwards, Medical Director at Mayo Clinic Health Solutions.
"For this reason, we believe physicians and other health care providers should be supporting these new technologies."
"This is especially important for patients with chronic diseases who need to track and manage their illnesses," he adds.
The software firm is also working with several other health organisations to provide content for the portal including the American Diabetes Association, the American Heart Association and New York Presbyterian Hospital.
The movement of sensitive details on to the web has understandably caught the attention of privacy organisations.
Dr Annie Anton, a privacy advocate and software professor at North Carolina State University, has examined HealthVault's privacy statement and believes there is a key problem with the site.
Writing on theprivacyplace.org website, Dr Anton said: "People don't realize is that HealthVault and similar PHR [public health record] systems are not subject to or governed by law."
HealthVault has raised concerns from privacy advocates
In particular, said Dr Anton, the site is not covered by the Health Insurance Portability and Accountability Act (HIPAA), a US federal law which sets out privacy regulations for the collection and movement of health information.
"When HIPAA was enacted, we did not envision that private software firms would eventually want to create databases for our health records," she wrote.
"As a result, HealthVault and other PHR systems are not subject to the same privacy and security laws to which traditional medical records are subject to in the United States."
She says this and other features of the site, such as where data will be stored and how it will be used raises serious questions about HealthVault.
But Microsoft says it has developed their tool with the blessing of privacy experts.
"Our privacy commitments were designed in conjunction with aggressive privacy advocates in parallel with the platform development," says Mr Nolan.
He points out that the site has a TRUSTe privacy seal, an independent program which vets the privacy statements of websites.
The scheme is part-sponsored by Microsoft.
"We conducted a 6-month outreach program with consumer advocate groups and were very careful to take the different perspective into account as we developed HealthVault."
The firm says its privacy practices will be audited by a third-party vendor and that it takes extra steps such as deleting cookies and search logs after 90 days.
"Additionally, search terms aren't saved from session to session, nor are advertisements related to the content in a HealthVault account," says Mr Nolan.
Features like this, whilst not perfect, are a step in the right direction says Guy Hosein, senior fellow at London-based human rights watchdog Privacy International.
"This would be a step in the wrong direction if they are advertising to you based on your ailments and adding this information to your personal profile."