We are excited to answer any and all questions you may have for us about COVID-19 and perhaps disease spillover and disease modeling in general! Either email us directly at [email protected] or use the form below.
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Here are some responses to questions we’ve received…
The SARS-CoV-2 virus is a new and very real threat to human life, so it is jarring to see some blatantly devalue the cost in human life of the current pandemic. The Institute of Health Metrics and Evaluation currently estimates that between 36,000 and 176,000 people will die from COVID-19, based on current models with 95% confidence. As of April 15th, the mortality for the disease in the US is about 4.4% and 16.35% of people diagnosed with COVID-19 have been hospitalized. What’s more, there is no vaccine available for SARS-CoV-2. This means that our response to the pandemic has to be very different – in order to limit the number of cases we have to change our behavior. The addition of COVID-19 cases on top of the normal requirements for our public healthcare system can also quickly overwhelm hospitals and clinics.
For some people, comparison to the common flu helps contextualize the impacts of COVID-19:
• SARS-CoV-2 (the virus causing COVID-19) is 20%-170% more infectious than influenza viruses (those which cause the seasonal flu)
• The hospitalization rates for cases of COVID-19 is around 20% while only around 2% for the flu. That’s 10 times as many people entering the hospital.
• COVID-19 kills between 10-100 times as many people who become infected than the common flu
Many viruses that are transmitted via respiratory droplets (spread through coughing, sneezing, touching one’s face, etc.) are considered ‘seasonal’. Being seasonal means that there is a predictable pattern in viral infections based on annual changes in the environment. For the seasonal influenza viruses (which cause the seasonal flu), the amount of time respiratory droplets stay in the air can be affected by humidity and temperature; the warmer the temperature, the faster the droplet will evaporate and the faster virus on surfaces will degrade. Humidity also plays a role in forcing droplets out of the air column. This is why during hot, humid spring and hot, arid summer seasons these respiratory viruses are transmitted at lower rates.
Now for SARS-CoV-2, we do not yet know the full story behind whether or not it will be seasonal, but we do have some evidence from closely-related viruses. There are actually a number of flu-like coronaviruses which circulate in people that are seasonal: increasing in prevalence during autumn/winter then decreasing in prevalence from spring to summer. Researchers have used data from these coronaviruses to create models that can predict how many COVID-19 cases there will be based on environmental variables like temperature and humidity, and many predict that SARS-CoV-2 will have a similar seasonal nature. This also agrees with other evidence on how temperature and humidity control SARS-CoV-2 persistence on different surfaces (see our blog post on this: https://montanacovid19.blog/coronavirus-surface-persistence/).
Although we have some reason to believe SARS-CoV-2 will be seasonal, there are many other factors that will play a role in how this specific virus will spread. Human factors such as travel, rates of contact, and susceptibility influence SARS-CoV-2 transmission much like environmental factors will, and it is difficult to say which factors will be more important. The importance of host factors is best shown when we look at outbreaks in countries in the southern hemisphere which was in the middle of summer when the pandemic began. Australia and Brazil have similar case number timelines as other countries in the northern hemisphere. This implies that human/host factors such as travel and susceptibility may play a more important role in spreading SARS-CoV-2 vs. environmental variables like temperature and humidity. So the answer is: SARS-CoV-2 may eventually become a more ‘seasonal’ infection, but don’t drop social distancing/travel restrictions just because it’s warmer outside. Human-related factors may be more important for transmission than environmental conditions!
Modeling paper predicting SARS-CoV-2 spread based on JHU data, SARS-CoV-1 data: https://www.medrxiv.org/content/10.1101/2020.03.12.20034728v3.full.pdf
Simple SIM modeling paper using seasonal coronavirus data to predict COVID-19 cases:
Clorox is a familiar brand name and wipes are easy to use on things like grocery cart handles, making them a good option to sanitize surfaces. Other vendors in the area are providing food-grade disposable or biodegradable gloves to customers, placing hand sanitizer near cart areas, and using hydrogen peroxide on common counter surfaces. These strategies may give customers peace of mind and may help reduce or eliminate the virus that causes COVID-19 on surfaces.
There are also many alternatives to single-use wipes that can be cheaper and produced in bulk for store use. For instance, conventional bleach is about 2-25 cents/oz (depending on brand, scent, additives, etc.), can produce a large quantity of disinfectant solution, and is extremely cheap (1:49 dilution). This can be used on disposable products (like soaking paper towels) or on reusable products (like rags and dish towels). If you are going to reuse items, they should soak in the bleach solution when not in use, and the solution should be replaced regularly. You can assure customers that you are providing similar levels of protection to name-brand, consumer-oriented products with bulk solutions (https://www.medrxiv.org/content/10.1101/2020.03.15.20036673v2.full.pdf – look at the Table on page 4).
For those that may be hypersensitive to bleach products, there are other possibilities! Consider alternatives like greater than 70% ethanol, 7.5% povidone-iodine, 0.05% chloroxylenol, 0.05% chlorohexidine, or 0.1% benzalkonium chloride solutions. These solutions all were effective at making the virus that causes COVID-19 undetectable within 5 minutes of application (https://www.medrxiv.org/content/10.1101/2020.03.15.20036673v2.full.pdf).
However, disinfectant procedures are not foolproof. As this question points out, it is crucial to focus on high-traffic areas (carts, registers, customer interfaces, etc.). It is also important to consider how long the disinfectant should remain on the surface it is applied in order to deactivate any virus present. The CDC recommends that a disinfectant with at least 1000 ppm sodium hypochlorite (bleach) remain in contact with the disinfecting surface for a minute (https://www.cdc.gov/coronavirus/2019-ncov/community/organizations/cleaning-disinfection.html). A 1000 ppm bleach solution corresponds to about 3 oz bleach per gallon of water. To ensure that disinfecting policies are effective, it may be necessary to spend longer disinfecting each surface.
The use of face masks (cloth or medical-grade filters) by employees and patrons is another technique stores have used to limit product contamination. There may soon be a reform in CDC guidelines as to the use of cloth masks by the general public (https://www.washingtonpost.com/health/cdc-considering-recommending-general-public-wear-face-coverings-in-public/2020/03/30/6a3e495c-7280-11ea-87da-77a8136c1a6d_story.html). This is a difficult decision for national healthcare professionals to make, as there is evidence that improper, repeated use of cloth masks may increase potential risk of infection. Masks without specially designed filters are also unlikely to offer much protection from the virus, and may provide a false sense of security. (https://www.google.com/url?q=https://bmjopen.bmj.com/content/5/4/e006577.short&sa=D&ust=1585941317951000&usg=AFQjCNHsv3dhyhZSlV4rHnHYBOZrOAZhGw). However, the use of facemasks by the general public, following CDC guidelines, can help others! It may reduce the potential for someone who is infected and contagious, but not showing symptoms (asymptomatic) to contaminate surfaces or infect others unwittingly. (https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30134-X/fulltext). As this situation develops in regard to national healthcare guidance, it will be important for employers (and the general public) to ascribe to said guidance. This means that you may wish to consider how you might supply employees with cloth masks and ensure employees use them properly.
Given that sanitation procedures may take longer than expected, many stores are now limiting public hours and spending more time cleaning. Similarly, it may be prudent to limit the number of customers in the store or the number of carts available to shoppers at a given time to reduce the number of potential contact surfaces for customers and to allow for sanitation between customer uses. Encouraging shoppers to provide their own masks, gloves, disinfectants may also prove useful. We hope this helps and please reach out with any more questions!
Preliminary evidence from a study in Wuhan, China suggests individuals with Type A blood could have a higher likelihood of SARS-CoV-2 infection and individuals with Type O blood may be less likely to be infected. SARS-CoV-1 from the 2003 pandemic is very similar to the SARS-CoV-2, and has a protein on its surface that makes it less likely to bind to host cells in the presence of anti-A antibodies. Anti-A antibodies are only found in people with Type B or Type O blood (https://doi.org/10.1101/2020.03.11.20031096).
Let’s go over what an antibody is: In order to replicate, a virus needs to enter and “overthrow” a host cell (like a human lung cell for SARS-CoV-2). The virus does this using proteins and sugars on its surface. Imagine a viral protein being a very specific key and the host cell entrance being a very specific lock. Our immune system tries to block the entrance of the key into the lock using antibody proteins. Imagine an antibody is like gum that sticks to the key so that it no longer fits the lock. Just like when antibodies target proteins on a virus surface, they can also target proteins on the surface of blood cells from different people, which is the reason blood transfusions are only possible between certain, compatible people.
It is important to note that all blood types are able to be infected, even though some are potentially less likely to be infected. So, we should all follow recommended sanitization and safety guidelines. Additionally, much of the information surfacing about SARS-CoV-2 is provided in a format known as a “pre-print”. This simply means that the information contained in the article may be important or timely, but that it has not yet been peer-reviewed by other scientists (as other scientific articles are). As such, statements based on pre-print media may need to be revised, revisited, or reconsidered as peer reviews occur or new evidence comes to light.