During the 1918 to 1920 global influenza epidemic, between 50 to 100 million people lost their lives, with over a quarter of the world’s population having being infected. Although vaccines might help in the event of a similar outbreak today, the possibility still remains that vaccine production would not be able to cope with such an influx in demand to make an important impact. In addition, hospitals would probably be overstretched, leaving many patients to be cared for by family members at home.

According to Richard Larson and Stan Finkelstein, members of MIT’s Engineering Systems Division (ESD), non-pharmaceutical interventions (NPIs) would be critical in these situations to minimize the spread of infection. Larson and Finkelstein want to inform people on how to avoid flu from spreading amongst family members and those living or working in close quarters. Larson, Mitsui Professor of Engineering Systems explains:

“We thought, let’s look at the dynamics of the home and see if there are any reasonably inexpensive steps that people could take to care for their loved ones and simultaneously minimize the chance of getting infected.”

Larson and Finkelstein’s study findings can be found in the December issue of Disaster Medicine and Public Health Preparedness, published by the American Medical Association.

They discovered that following simple steps, such as washing hands properly, wearing masks and strategically controlling temperature, humidity and air circulation, could all assist in decreasing the risk of flu from spreading. Even though their recommendations are based on fighting pandemic flu, these measures could also prevent the spread of the common seasonal flu, which typically kills about 30,000 people each year in the U.S.

Fighting back against flu

Larson, Finkelstein and team’s motivation mainly stems from growing concerns over potentially devastating flu strains, such as H5N1. For the past five years the team studied influenza with a focus on NPIs to prevent the disease from spreading.

For their latest report, Larson, Finkelstein and team re-examined 40 studies in terms of their effectiveness for various non-pharmaceutical interventions. They detected approaches that have been proven to reduce the transmission of the flu viruses that are spread when an infected person emits fluids containing particles with the virus through coughing, sneezing, talking or breathing. These particles may come in direct contact with another person, or they can be transmitted through touching surfaces that have previously been touched by an infected person. The viruses are also airborne and can be transmitted through inhalation.

According to the researchers the following steps can be taken to prevent transmission:

  • By thoroughly washing your hands after being in a room with an infected person, i.e. scrubbing your hands with soap and water, or an alcohol-based hand sanitizer for 20 to 30 seconds, which is about the time it would take to sing “Happy Birthday” twice.
  • By wearing a mask. Although opinions are divided as to whether masks can block airborne viruses, Finkelstein, a senior research scientist in ESD, who is also an associate professor at Harvard Medical School says: “one thing we learned from the literature that we looked at is that if the healthy person is wearing a mask and walks into a sickroom and touches infected surfaces, the mask makes it hard to touch his or her own nose and mouth.”
  • By installing air filters. Almost 98% of virus particles can be removed through high-efficiency particulate air (HEPA) filters. Portable air purifiers are also useful; the same as pointing a window fan out the window of the sickroom.
  • By installing an ultraviolet light as UV light is antimicrobial. Portable air purifiers with both UV lamps and HEPA filters can be purchased for $180 to $370.
  • By controlling temperature and humidity. Viruses can be disabled and killed by higher temperatures and humidity levels.

According to Larson, evidence that these measures reduce the transmission of flu already exist:

“Nothing we’re proposing is controversial. Our contribution is systemically going through the decades of scientific literature and picking out what we thought were exemplary pieces of work and putting them in an engineering systems framework.”

Minimizing risk

The researchers calculated the rate in which flu was spread by multiplying an infected persons’ number of face-to-face contacts during one day with the probability of the infection being spread from the infected person to one who is susceptible. They state that the rate can be reduced by certain factors, such as minimizing the number of people who get in contact with the sick person and by taking the steps outlined in this paper.

Larson comments:

“It’s not going to reduce the risk to zero, and do we scientifically know what percentage the risk is reduced by this? No. But we feel confident that it’s significant, if the majority of these steps are taken.”

The price of these preventive measures varies depending on how many measures are adopted, i.e. from just a few dollars up to $1,000. Whilst washing your hands thoroughly and wearing a facemask represents negligible cost, air filters and other technologies can cost a few hundred dollars, however, according to the researchers taking any of these steps is better than doing nothing at all.

Finkelstein and Larson will be meeting CDC officials in February to present their findings. They aim to encourage the CDC to add these measures to the agency’s official list of recommendations to assist in the battle against influenza.

Larson states:

“It’s a pretty good investment to reduce the chance of getting infected. We’re hoping that the CDC will buy into this and have this as part of their portfolio of educating the American public.”

Written by Petra Rattue