by Buck Institute

Preventing Pathogen Passage: Taking Precautions Against a Pandemic

This is the 2nd blog in our series from MS Biology students from Dominican University. In this post, student authors Michael Broussalian, Asia Davis-Castillo, Haeli Lomheim, and Charles Lau cover science-based advice for preventing the spread of COVID-19 and other infectious diseases. You can read the first blog, about vaccines, here.

Michael Broussalian, Asia Davis-Castillo, Haeli Lomheim, and Charles Lau;
Edited by Dr. Pankaj Kapahi, Buck Professor

According to reports by the World Health Organization (WHO), since the start of the Coronavirus pandemic about 1 in 12 people in California have had COVID-19. Contrast this with New Zealand, where just 1 in 2,470 people have been infected with the virus. Even more dramatically, take a look at Vietnam where just 1 in 46,547 have had the virus. What did New Zealand and Vietnam do right that California – and the rest of the United States - did wrong?

The answer is disarmingly simple: the governments with the most successful outcomes followed the rules given by the WHO. Additionally, they worked with their citizens to make sure that as many people as possible followed those rules. 

So what are these rules that wondrously saved these countries? You’ve heard them all before:

  • Testing
  • Tracing
  • Hand-washing
  • Social Distancing
  • Mask-Wearing

Why are these fairly simple ideas so effective, and why are some people not taking them to heart?

Testing and tracing are pretty self-explanatory. When you test positive for a virus, this informs you that you need to isolate yourself to prevent passing the virus to someone else. This is important because when you contract a virus, it hijacks your body’s machinery to produce more of itself. This also makes your breath, specifically the water droplets in your breath, a vehicle for the virus to escape from your body. And much like closing a door to a room to keep a fly from leaving, by isolating yourself you are keeping the virus from spreading to other areas where other people could be in contact with it. 

But what if you didn’t think you had the virus until you got the test result back and didn’t know to isolate yourself? This is a situation where contact tracing is essential. Contact tracing involves reporting to healthcare officials about all the places you had gone since you had first contracted the virus. This information is solely used to contact people who have also recently been to those places so that they know to isolate themselves before they are in the same sticky situation that you had been in originally. This stops the accidental spread of the virus before it gets too out of control to keep everyone safe. Efforts towards testing and tracing had begun in the countries mentioned above very early on in the COVID-19 timeline, months before California, thus giving people more opportunities to self-isolate before unknowingly spreading the virus.

First, the easy stuff


As recommended by the CDC, handwashing with soap and water can reduce the amounts of bacteria and chemicals on hands. In absence of soap and water, using a hand sanitizer with at least 60% alcohol can help to avoid getting sick and spreading germs to others as well.

But what works better? Hand washing or hand sanitizer? A 2005 study compared hand washing with antiseptic soap and hand sanitizing with an alcohol-based hand sanitizer. Researchers studied the two forms of hand sterilization in neonatal care centers in 2 New York Hospitals and tested the rate of infection and microbial counts on the skin after washing. They found that there was no significant difference between hand washing and hand sanitizing with a 95% confidence interval when hands did not have solid waste on them.  However, they did find that the skin condition of the nurses' hands was better when they used more alcohol-based sanitizer versus consistently hand washing. However, if there was visible solid matter on the hands before sanitization, hand sanitizer was found to be less effective.

Social Distancing

Studies show that social distancing is important to reduce the droplet transmission of COVID-19. It’s difficult, however, to tease out the independent impact of social distancing from other mitigation efforts, because when social distancing is implemented so typically are masks, sanitization efforts, and other preventative practices. One study by the Ohio Department of Health did indicate that countries that had stricter regulations and implemented social distancing earlier were able to flatten the curve much more quickly. While people have argued that the 6 feet rule seems arbitrary, that distance has been the standard for other diseases such as cystic fibrosis (CF) in medicine. CF patients sharing bacteria is extremely dangerous and can lead to death. Because bacteria is transmitted via droplets between patients, they need air repulsion. It is held that 6 feet is the minimum amount of space that is considered safe between two infection patients with CF. Because COVID-19 is transmitted via droplets, it's been concluded that without strong directional airflow 2 meters  (about 6 feet) is a safe distance to avoid droplet transmission.

Masks: Unmasked

What type of mask should you be wearing?

Mask type and efficacy are important factors in everyday prevention of COVID-19 spread.  An N95 respirator is the most effective mask for droplet protection as it fits tightly around the face and has the most effective filter.  However, using a new N95 every day is not a sustainable option for most people.  We must resort to disposable medical masks and reusable fabric masks.  

Kwon, 2020

Medical masks are loose-fitting, but they do filter out large airborne particles.  Cloth masks can be effective when made and used correctly. Absorbent material such as cotton mostly does not filter airborne particles. According to CDC guidelines, a cloth mask should be made with at least 3 layers with a water-resistant material for the outer layer. They can also be made with a pocket for a disposable filter. Masks can be reused if washed properly or left to decontaminate in an area where they won’t be touched for a few days, such as in a paper bag.

Wearing a mask: A simple guide

A mask should fit snugly around your face, covering both your nose and chin.  There should not be large gaps on any sides that allow free airflow through. While wearing the mask, do not touch it with your hands without washing or sanitizing them first, and never touch the front of the mask with your hands. The mask should fit on your face tightly enough that both your inhale and exhale flow through the front of the mask and not the sides.  

How are masks tested for efficacy?

In a study for the efficacy of different types of masks, two mannequin heads were put in a test chamber, one connected to a compressor nebulizer that exhaled a viral suspension mist to mimic a potential virus spreader, and the other connected to a ventilator through a virus particle unit.  The ventilator rate was set to mimic the steady state in adults, about 18 breaths per minute.  The various face masks were attached to the mannequin heads using the manufacturer’s instructions.  Note that there can be no randomized controlled studies for the efficacy of mask use (because we cannot purposely infect humans with COVID), so this experiment is meant to mimic human behavior to accurately portray mask efficacy. 

Ueki, 2020

Below are some of the types of masks that were tested for droplet protection. One important goal of this study was to determine how to make an average fabric mask more effective. Different types of fabric masks were compared with N95 and medical masks using two droplet sizes. Check out this page for more mask comparisons.

Note that the masks made of cotton were about 55% effective against the larger sized droplets. However, when a filter such as a dried baby wipe or a piece of vacuum bag was added, the filtration percentage increased to nearly that of the N95 or medical mask.

Whiley, 2020

Wearing a Mask Post-Vaccination

After receiving the COVID-19 vaccine, it is still important to wear a mask.  Like other vaccines, the COVID-19 vaccine does not provide 100% immunity.  COVID-19 still has a large presence although vaccinations have helped lower case numbers. The  vaccines from Pfizer and Moderna are about 95% effective, but vaccinated people may still spread the virus, and there is still a 5% chance they can contract the virus.  

More research is needed to confirm whether the current vaccines will be effective against emerging strains. While new strains are circulating, it is imperative that people continue to wear masks.  

In addition, some people have already contracted COVID-19 and therefore possess antibodies for that strain and feel that wearing a mask is no longer necessary.  However, although reinfection is rare, it has been reported. There is growing evidence that some circulating mutant strains can reinfect people who have already recovered from COVID-19. Wearing a mask is not only crucial for protecting yourself and others, it is likely the easiest preventative action people can take against COVID-19.  

The Infodemic

Another problem that challenges pandemics is something caused not by viruses, but by humans: misinformation. The WHO coined the term, “infodemic” for this widespread abundance of information. With an excess amount of information spreading out of control like a wildfire, false information is bound to spread in addition with good information. Some may wonder, what is the worst that can happen? Misinformation can be harmless, sure, but it can also be deadly. For example, when hydroxychloroquine was over-sensationalized as a potential cure for COVID-19, a man died from ingesting a fish tank cleaner that listed chloroquine as an ingredient; his wife was hospitalized from ingesting it as well. Clearly, misinformation can be fatal.

Misinformation does not only exist in this coronavirus pandemic. According to a paper published in BMC Public Health, misinformation of the Ebola virus was also found on Twitter.  In 2014, there was an Ebola communication crisis that generated widespread fear and attention in the United States. The goal of this study was to describe the content of Ebola-related posts that focused on misinformation, political content, health-related content, and a few other characteristics.

“Discord-inducing statements and political messages were both significantly more common in tweets containing misinformation compared with those without.”

Trotochaud et al. 2020.

The chart above depicts the amount of information that was analyzed throughout these Twitter posts. To summarize, messages that contained misinformation were 35% more likely to promote discord when compared to posts that contained true information. This also proves to be dangerous because it shows that false information is more likely to spread faster due to containing discord messages.

Image retrieved from WHO.int

What you can do?

Image retrieved from groundviews.org

Participating in public health awareness campaigns

Being a part of health awareness campaigns sponsored by a reliable organization can help increase the circulation of factual information. To battle discord-promoting misinformation, it is important to have the voice of truth be louder than others. Especially with information being so readily at hand, information exchange has never been faster before. Public health awareness campaigns are a good opportunity to spread right information as well as become a learning experience.

Engaging in media literacy efforts

Engaging in media literacy efforts means to critically evaluate information that is being circulated.  Spreading awareness of what is misinformation will not only help those who spread factual information, but also debunk misinformation being spread.

Social listening with AI

'“Countering fake news or rumours is actually only responding or mitigating when it’s too late,” said Nguyen. “What we’ve put in place in the beginning of the pandemic is what we call a social listening approach.”’ -Tim Nguyen, Head of Unit, High Impact Events Preparedness at WHO

The WHO uses machine learning on social media platforms to search for newly developed health taxonomies and categorize them into the cause, the illness, the interventions, and the treatment. This helps the WHO track information that is gaining popularity in a timely manner. In addition, machine learning can provide insights on emotions based on what the users are writing. With this type of information, the WHO can take a more delicate approach to battling misinformation. 

Resources for fact checking

The WHO has dedicated a website to help us all do our part towards the battle against an infodemic. 


This webpage is dedicated to stopping the spread of misinformation. Essentially it serves to debunk false information that has already reached mainstream media. More information can be found here.


Report Misinformation

Finally, a way to stop misinformation would be reporting when you see it. Many social media platforms have already established a feature such as this. More information can be found here.

Images retrieved from WHO.int

How does this thing end?

This is a question near the top of everyone’s list. Let’s address it by taking a look at some recent epidemics and see how they ended. The H1N1 “Swine Flu” epidemic (2009, ~284,000 deaths globally) was ended by distribution of antiviral drugs to infected individuals, flu vaccinations given to most of the population, consistent social distancing, and prolonged closing of public spaces. The Ebola Virus pandemic (2013, 11,000+ deaths) was ended by healthcare agencies monitoring patient care & recovery, thorough contact tracing, dispersion of information to the public on how to reduce transmission risk, and increasing vaccine availability in heavily impacted regions. The Haitian Cholera Outbreak (2010, 10,075 deaths) was ended by educating the public on sanitation practices, and continued monitoring of disease spread. 

All in all, preventative practices recommended by the WHO, like tracing, testing, and isolating, must be maintained by most of the public until vaccinations are widely available for the COVID-19 pandemic to end.  And hopefully by the end of this article, we’ve shown that the preventative measures we’ve been told to follow are easy, harmless, and have a huge impact if done consistently. 

“I think we all know now COVID-19 is here for the long term. We have to live with the risk and manage the risk, while ensuring and enabling the people to move about and respecting their fundamental human rights,” - Dr. Kang Kyung-wha, Minister of Foreign Affairs, South Korea


Kwon, Diana. “How Face Masks Can Help Prevent the Spread of COVID-19.” The Scientist Magazine®, 8 July 2020, www.the-scientist.com/news-opinion/how-face-masks-can-help-prevent-the-spread-of-covid-19-67646. 

Larson EL, Cimiotti J, Haas J, Parides M, Nesin M, Della-Latta P, Saiman L. Effect of antiseptic handwashing vs alcohol sanitizer on health care-associated infections in neonatal intensive care units. Arch Pediatr Adolesc Med. 2005 Apr;159(4):377-83. doi: 10.1001/archpedi.159.4.377. PMID: 15809394.

Matrajt L, Leung T. Evaluating the Effectiveness of Social Distancing Interventions to Delay or Flatten the Epidemic Curve of Coronavirus Disease. Emerg Infect Dis. 2020 Aug;26(8):1740-1748. doi: 10.3201/eid2608.201093. Epub 2020 Apr 28. PMID: 32343222; PMCID: PMC7392458.

Sommerstein R, Fux CA, Vuichard-Gysin D, Abbas M, Marschall J, Balmelli C, Troillet N, Harbarth S, Schlegel M, Widmer A; Swissnoso. Risk of SARS-CoV-2 transmission by aerosols, the rational use of masks, and protection of healthcare workers from COVID-19. Antimicrob Resist Infect Control. 2020 Jul 6;9(1):100. doi: 10.1186/s13756-020-00763-0. PMID: 32631450; PMCID: PMC7336106.

Ueki, Hiroshi et al. “Effectiveness of Face Masks in Preventing Airborne Transmission of SARS-CoV-2.” mSphere vol. 5,5 e00637-20. 21 Oct. 2020, doi:10.1128/mSphere.00637-20

Whiley, Harriet et al. “Viral Filtration Efficiency of Fabric Masks Compared with Surgical and N95 Masks.” Pathogens (Basel, Switzerland) vol. 9,9 762. 17 Sep. 2020, doi:10.3390/pathogens9090762

Sell, T. K., Hosangadi, D., & Trotochaud, M. (2020). Misinformation and the US Ebola communication crisis: analyzing the veracity and content of social media messages related to a fear-inducing infectious disease outbreak. BMC Public Health, 20(1). https://doi.org/10.1186/s12889-020-08697-3

World Health Organization. Immunizing the public against misinformation. World Health Organization. https://www.who.int/news-room/feature-stories/detail/immunizing-the-public-against-misinformation.


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