In the midst of the recent swine flu outbreak a debate emerged over the benefits of wearing a facial mask versus using a respirator to prevent infection. Last spring people in some parts of the U.S. were seen wearing masks as a precaution against the virus, but federal health officials said they didn't know how helpful either type of device is in preventing swine flu infection.

Most people seen wearing masks were wearing face masks, which are loose-fitting and designed to help stop droplets from spreading from the person wearing the mask. They are more comfortable to wear for longer periods and also protect the user's mouth and nose from splashes, according to the report. Respirators, on the other hand, are designed to protect the user from breathing in very small particles. They are similar to the facemasks but have a filtering ability and fit more snugly so that most air is breathed through the filter material.

According to the Centers for Disease Control and Prevention (CDC; Atlanta), both facemasks and respirators need to be worn correctly and consistently throughout the time they are used in order to offer optimal protection. (See Tables 1-2 for CDC guidance on facemasks and respirators.) Although respirators, if worn and fitted correctly, will provide protection against most small particles, the CDC notes that there is limited evidence available to suggest that use of a respirator without fit-testing may still provide better protection than a facemask against inhalation of small particles.

As a result of the swine flu outbreak, Clinova (Southampton, England) said it has seen a surge in demand for its Covaflu filtering facepiece (FFP3), a device that provides filtering capability and face fit and is designed to protect against both droplets and fine aerosols. According to Clinova, studies have shown that 20% to 85% of virus particles can penetrate two ordinary types of surgical mask, but masks with FFP3 respirators, such as the Covaflu FFP3, will block more than 99% of airborne virus droplets that are 0.3 microns in size. Most swine flu-infected droplets will be larger than this, the company noted.

Clinova says its Covaflu FFP3 facemasks meet World Health Organization (Geneva), CDC, and the UK Health and Safety Executive standards for use in influenza pandemics.

As health experts continue to debate the benefits of facemask and respirators to prevent infection, researchers at Stanford University School of Medicine (Stanford, California) are busy trying to help public health authorities come to grips with future flu pandemics.

Matthew Callaghan, MD, a postdoctoral scholar in medicine who is affiliated with Stanford's Biodesign Program, a joint venture between the schools of Engineering and Medicine, told 84 Medical Device Daily that most of the researchers at Stanford who are working on bioterrorism and pandemic-related projects began their work two years ago when the H5N1, or avian flu, was a big threat. The recent outbreak of the swine flu served as a reminder to them that they hadn't really gotten as far as they would have liked since the avian flu, Callaghan said.

"I think a lot of protocols were written up ... but as far as actually spending money and advancing physical infrastructures, not as much as I would have liked to see," Callaghan said.

A Stanford team led by Callaghan — and including Joelle Faulkner, another biodesign fellow, medical student Dhruv Boddupalli and mechanical engineering graduate student William Bishop — has produced prototypes of a ventilator, relatively free of bells and whistles that can be assembled from off-the-shelf components, according to Callaghan.

Any large-scale flu pandemic is going to leave hospitals short on ventilators, Callaghan said, a device that assists breathing in instances of severe respiratory distress. Government studies have estimated a national shortage of almost 750,000 ventilators in the event of a serious influenza pandemic, he said, yet standard hospital models cost anywhere from $30,000 to $60,000 a piece. "Even the stripped-down, portable ventilators found in ambulances cost between $4,000 and $6,000 a piece," Callaghan said.

Callaghan said. "We set out to create a device specifically made for stockpiling in the event of a pandemic. You don't need the functionality of the $50,000 model," he said.