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Health & Sciences: A consolidated scientific guide in understanding COVID-19 (Part 1)
Lately, the coronavirus disease 2019 (COVID-19) has been hitting cities all over the world. From its discovery in a wet market in Wuhan, the capital of Hubei, China on December 31, 2019 to its widespread transmission to other continents, there have been more than a million cases worldwide (Gutiérrez, 2020). Because of this, the World Health Organization (WHO) declared COVID-19 as a “pandemic” on March 11 because it has spread worldwide and could possibly infect almost everyone (Ducharme, 2020).
Figure 1. Exponential increase of COVID-19 cases across the globe as of April 7. Note that the last point of the graph reached beyond the 1 million x-axis.
Consequently, our governments struggle to deal with the disruption of major industries and sectors. Together with frontliners like nurses and doctors, they cater to the safety and security of our fellowmen. In addition, as we try to understand this new, complex disease, we feel anxious about its possible threats.
Fortunately, scientists are able to relieve our uncertainty. As they debunk bogus rumors about the disease, they give us authentic, credible information. They provide us a more rational and knowledgeable perspective as they undergo intensive research and experiments. For instance, they inform us of the nature of the disease, its effects to us humans, and the ways we could prevent contraction and transmission.
With that, scientific findings for COVID-19 will be summarized in the next paragraphs. In the first part of this guide, the technical aspects of the disease will be discussed.
Epidemiological nature of the COVID-19
WHO (2020) declares that as of February 11, coronavirus disease (COVID-19) is the official name of the sickness itself. Its pathogen is a virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which superseded the name novel coronavirus (2019-nCoV) last January 31.
As suggested by the name of the virus, it belongs to the coronavirus family. According to the Center for Disease Control and Prevention (CDC, 2020), coronaviruses are named for their “crown-like spikes on their surface”. They mainly affect our respiratory system – the system responsible for our breathing (NIAID, 2020). Some coronaviruses that caused similar outbreaks in the past decades include SARS-CoV (which caused severe acute respiratory syndrome in 2002) and MERS-CoV (which caused Middle East Respiratory Syndrome in 2012).
The recent report from the WHO (2020) China Joint Mission classifies COVID-19 as a zoonotic disease. This means that the disease is mainly transmitted through contact with animals. This was firstly assumed as those who frequented the Wuhan wet markets selling livestock and exotic animals contracted the disease. While there’s no determined host as of now, scientists suspect that bats are the reservoirs carrying the SARS-CoV-2 (Bangkok Post, 2020; Rothan & Byrareddy, 2020).
Modes of transmission (MoTs) of the COVID-19
COVID 19 has two MoTs. According to the same report by WHO (2020), the first transmission mainly occurs through respiratory aerosols that are 5 to 10 micrometers wide (Note: This is different from airborne transmission, where the droplets have a diameter of less than 5 micrometers.). These droplets are released when a person sneezes or coughs. They can then be inhaled by people who are nearby. However, since COVID-19 can be spread by people who are asymptomatic (i.e. do not manifest symptoms), even close contact with a person who has COVID-19 is enough to spread the virus (WHO, 2020; Woodward, 2020).
Much scarier, Dr. Harvey Fineberg, chair of National Academy Sciences’ Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats, shares research findings claiming that the virus can be spread through droplets from talking and even breathing. According to him, “...[coronavirus] could be spread via aerosols generated directly by patients' exhalation.” (Guardian, 2020).
The second mode of transmission occurs through fomites. These are objects whose surfaces could be contaminated by the virus. Fomites can be passed onto people if they touch these objects (WHO, 2020). Studies from University of California, Los Angeles (UCLA) and the New England Journal of Medicine suggest that the virus can stay up to four hours on copper, a day on cardboard and even up to 2 or 3 days on plastic and stainless steel (UCLA, 2020; Van Doremalen et al., 2020).
Factors affecting the contraction and transmission of COVID-19
According to Tom Kotsimbos, a respiratory physician, “Anybody can contract COVID-19” (Guardian, 2020). Those 18 years old and below seem to be the least affected group (WHO, 2020). Meanwhile the following categories are at a higher risk for COVID-19:
1. the elderly, i.e. people aged 60 and above (CDC, 2020, Rothan & Byrareddy, 2020; WHO, 2020),
2. those having underlying diseases like asthma (CDC, 2020), hypertension (WHO, 2020; Rothan & Byrareddy, 2020), diabetes (CDC, 2020; Rothan & Byrareddy, 2020), etc.,
3. medical workers and other health care providers (CDC, 2020; Rothan & Byrareddy; WHO, 2020), and,
4. pregnant people, in the sense that they are more susceptible to respiratory diseases (CDC, 2020; Rothan & Byrareddy, 2020)
On the other hand, the factors affecting transmission of COVID-19 are highly variable and thus still unclear (Antrim, 2020; WHO, 2020). Some researchers hypothesize that SARS-CoV-2 could stay in the water or air. Its humidity and temperature could possibly speed up or impede the transmission process itself.
Harmful effects of COVID-19 to the human body
Figure 2. Body system disorders caused by COVID-19.
As mentioned in the introduction, COVID-19 mainly impairs the respiratory system. Its effects are similar to those of MERS and SARS. According to the Department of Health (2020) and Kandola (2020), the SARS-CoV-2 mainly infects the lining of the pharynx (throat), trachea (windpipe), and lungs.
Symptoms vary from person to person. Usually, it takes about 5 to 6 days after infection for a person to display symptoms (WHO, 2020). Common symptoms (reported by around 4 out of 5 patients) include the following (DOH, 2020; WHO, 2020):
1. fever (38º C),
2. runny nose,
3. sweats & chills,
4. coughs and colds, and
5. shortness of breath.
Sources (in APA format)
• Antrim, A. (2020, March 20). Environmental engineers identify factors affecting COVID-19 transmission. Contemporary Clinic. Retrieved 5 April 2020 from https://contemporaryclinic.pharmacytimes.com/news-views/environmental-engineers-identify-factors-affecting-covid-19-transmission
• Bangkok Post. (2020, January 23). Why wild animals are a key ingredient in China's coronavirus outbreak. Retrieved 4 April 2020 from https://www.bangkokpost.com/world/1842104/why-wild-animals-are-a-key-ingredient-in-chinas-coronavirus-outbreak.
• Centers for Disease Control and Prevention [CDC]. (2020, February 15). Human coronavirus types. Retrieved 2 April 2020 from https://www.cdc.gov/coronavirus/types.html.
• CDC. (2020, April 2). People who are at higher risk for severe illness. Retrieved 5 April 2020 from https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-at-higher-risk.html.
• Ducharme, J. (2020, March 11). World Health Organization declares COVID-19 a 'pandemic.' Here's what that means. Time. Retrieved 3 April 2020 from https://time.com/5791661/who-coronavirus-pandemic-declaration/.
• Guardian. (2020, March 18). Coronavirus: the science of how Covid-19 affects the human body. Retrieved 4 April 2020 from https://www.theguardian.com/australia-news/audio/2020/mar/19/coronavirus-the-science-of-how-covid-19-effects-the-human-body?fbclid=IwAR1wZET59EdV0CN0VXjgAVEcIlIodqmk7uO67pfRVS3rIyVRJ0ap_2bW1V4.
• Gutiérrez, P. (2020, April 4). Coronavirus world map: which countries have the most cases and deaths?. Guardian. Retrieved 5 April 2020 from https://www.theguardian.com/world/2020/apr/04/coronavirus-world-map-which-countries-have-the-most-cases-and-deaths.
• Kandola, A. (2020, March 25). How does coronavirus affect the body?. Medical News Today. Retrieved 3 April 2020 from https://www.medicalnewstoday.com/articles/coronavirus-effects-on-body?fbclid=IwAR1CXuLBkO2IyBLksdAj-bSeiq3Ls_DOmCme_QdIidKPz5YU9CqPF1GvlzM.
• McKeever, A. (2020, February 18). Here’s what coronavirus does to the body. National Geographic. Retrieved 3 April 2020 from https://www.nationalgeographic.com/science/2020/02/here-is-what-coronavirus-does-to-the-body/?fbclid=IwAR1cpKImt_PqizPjhGARR2vD4yV3mOjNEsU7QtosFXSWTqGZo0Re_j6rz4g.
• National Institute of Allergy and Infectious Diseases [NAIAD]. (2020, March 25). Coronaviruses. Retrieved 4 April 2020 from https://www.niaid.nih.gov/diseases-conditions/coronaviruses.
• Rothan, H.A. & Byrareddy, S.N. (2020). The epidemiology and pathogenesis of coronavirus disease (COVID-19) outbreak. Journal of Autoimmunity. Retrieved from https://www.sciencedirect.com/science/article/pii/S0896841120300469?via%3Dihub.
• University of California - Los Angeles [UCLA]. (2020, March 20). Study reveals how long COVID-19 remains infectious on cardboard, metal and plastic: People may acquire coronavirus through air and by touching contaminated surfaces. ScienceDaily. Retrieved April 4, 2020 from www.sciencedaily.com/releases/2020/03/200320192755.htm.
• Van Doremalen et al. (2020, March 17). Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. New England Journal of Medicine. Retrieved 4 April 2020 from https://www.sciencedirect.com/science/article/pii/S0896841120300469?via%3Dihub.
• World Health Organization [WHO]. (2020, February 28). Report of the WHO-China joint mission on coronavirus disease 2019 (COVID-19). Retrieved 4 April 2020 from https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf.
• WHO. (2020, March 18). Basic protective measures against coronavirus. Retrieved 2 April 2020 from https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public.
• WHO. (2020, March 29). Vías de transmisión del virus de la COVID-19: repercusiones para las recomendaciones relativas a las precauciones en materia de prevención y control de las infecciones [Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations]. Retrieved 3 April 2020 from https://www.who.int/es/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations.
• Woodward, A. (2020, April 3). It's estimated 1 in 4 coronavirus carriers could be asymptomatic. Here's what we know. Science Daily. Retrieved 4 April 2020 from https://www.sciencealert.com/here-s-what-we-know-so-far-about-those-who-can-pass-corona-without-symptoms.
However, in extreme cases, further health complications are possible, such as (WHO, 2020):
1. acute respiratory distress syndrome (ARDS), which causes fluid to leak into the lungs,
2. pneumonia, which inflames the alveoli (air sacs in the lungs) through pus, and
3. multiple organ failure.
1. acute respiratory distress syndrome (ARDS), which causes fluid to leak into the lungs,
2. pneumonia, which inflames the alveoli (air sacs in the lungs) through pus, and
3. multiple organ failure.
Graham Readfearn, a reporter for Full Story, adds that COVID-19 pneumonia has major differences from common pneumonia (Guardian, 2020). The first difference is that COVID-19 pneumonia is viral, which means that medicine alone could not eradicate the virus causing the lung inflammation. For instance, other factors such as temperature and ventilation have to be considered in the treatment. This is contrary to the bacterial nature of common pneumonia, where antibiotics are usually given to treat it.
Furthermore, unlike common pneumonia which mainly swells the alveoli, COVID-19 pneumonia tends to affect not just the air sacs of the lung(s), but the whole lung(s) itself/themselves. As attested by Kotsimbos, “Breathing in and breathing out becomes a challenge.”
A report from McKeever (2020) finds out that COVID-19 could also affect organs outside the respiratory system. They are the following: the digestive system which aids in breaking down the food we eat, the immune system that fights infection inside our body, and the excretory system that expels waste from our body.
First, diarrhea occurs in the digestive system. This is because the virus SARS-CoV-2 could bind with random receptors (protein structures that receive signals and stimulate bodily responses) that match it (Rothan & Byrareddy, 2020). In this case, the virus finds the receptors of the digestive system (i.e. stomach and small intestine) compatible. The process is analogous to fitting a lock (receptor) and key (virus) together.
Second, a surge of cytokines happen in the immune system. At a healthy amount, these proteins signal immune cells to kill harmful bacteria. However, in the case of COVID-19 where multiple tissues are infected, cytokines seem to kill healthy bacteria as well. They cause the extreme complications mentioned above (WHO, 2020).
Lastly, COVID-19 could affect the liver and kidneys of the excretory system, albeit not yet fully investigated. For the former organ, it is important that it has vessels not only carry & filter blood but also secrete enzymes that facilitate body processes. However, these enzymes proliferate in COVID-19, which could lead to the failure of the organ itself (WHO, 2020). On the other hand, the latter organs help in filtering blood through nephrons. However, the nephrons can be injured as small tubes called tubules (in the nephrons) trap the virus.
WHO (2020) states that currently, eight percent of the patients recover, while about 17 percent of them seriously ill. Six percent of the sick get the life-threatening pneumonia and subsequently perish.
Below is a table summarizing the important facts of COVID-19:
Official Names
| Disease: Coronavirus disease (COVID-19) |
| Pathogen: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) | |
Transmission
| Originally, from animals to humans |
| Human-to-human: respiratory droplets (5-10 micrometers), fomites | |
Factors
| Age, having underlying diseases; variable environment conditions |
Effects
| Respiratory system: coughs & colds, shortness of breath, ARDS, pneumonia |
| Others: diarrhea, cytokine storm, nephron injury |
Here is the link for the second part of the scientific guide: http://upismc.blogspot.com/2020/04/health-sciences-consolidated-scientific_8.html.
Sources (in APA format)
• Antrim, A. (2020, March 20). Environmental engineers identify factors affecting COVID-19 transmission. Contemporary Clinic. Retrieved 5 April 2020 from https://contemporaryclinic.pharmacytimes.com/news-views/environmental-engineers-identify-factors-affecting-covid-19-transmission
• Bangkok Post. (2020, January 23). Why wild animals are a key ingredient in China's coronavirus outbreak. Retrieved 4 April 2020 from https://www.bangkokpost.com/world/1842104/why-wild-animals-are-a-key-ingredient-in-chinas-coronavirus-outbreak.
• Centers for Disease Control and Prevention [CDC]. (2020, February 15). Human coronavirus types. Retrieved 2 April 2020 from https://www.cdc.gov/coronavirus/types.html.
• CDC. (2020, April 2). People who are at higher risk for severe illness. Retrieved 5 April 2020 from https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-at-higher-risk.html.
• Ducharme, J. (2020, March 11). World Health Organization declares COVID-19 a 'pandemic.' Here's what that means. Time. Retrieved 3 April 2020 from https://time.com/5791661/who-coronavirus-pandemic-declaration/.
• Guardian. (2020, March 18). Coronavirus: the science of how Covid-19 affects the human body. Retrieved 4 April 2020 from https://www.theguardian.com/australia-news/audio/2020/mar/19/coronavirus-the-science-of-how-covid-19-effects-the-human-body?fbclid=IwAR1wZET59EdV0CN0VXjgAVEcIlIodqmk7uO67pfRVS3rIyVRJ0ap_2bW1V4.
• Gutiérrez, P. (2020, April 4). Coronavirus world map: which countries have the most cases and deaths?. Guardian. Retrieved 5 April 2020 from https://www.theguardian.com/world/2020/apr/04/coronavirus-world-map-which-countries-have-the-most-cases-and-deaths.
• Kandola, A. (2020, March 25). How does coronavirus affect the body?. Medical News Today. Retrieved 3 April 2020 from https://www.medicalnewstoday.com/articles/coronavirus-effects-on-body?fbclid=IwAR1CXuLBkO2IyBLksdAj-bSeiq3Ls_DOmCme_QdIidKPz5YU9CqPF1GvlzM.
• McKeever, A. (2020, February 18). Here’s what coronavirus does to the body. National Geographic. Retrieved 3 April 2020 from https://www.nationalgeographic.com/science/2020/02/here-is-what-coronavirus-does-to-the-body/?fbclid=IwAR1cpKImt_PqizPjhGARR2vD4yV3mOjNEsU7QtosFXSWTqGZo0Re_j6rz4g.
• National Institute of Allergy and Infectious Diseases [NAIAD]. (2020, March 25). Coronaviruses. Retrieved 4 April 2020 from https://www.niaid.nih.gov/diseases-conditions/coronaviruses.
• Rothan, H.A. & Byrareddy, S.N. (2020). The epidemiology and pathogenesis of coronavirus disease (COVID-19) outbreak. Journal of Autoimmunity. Retrieved from https://www.sciencedirect.com/science/article/pii/S0896841120300469?via%3Dihub.
• University of California - Los Angeles [UCLA]. (2020, March 20). Study reveals how long COVID-19 remains infectious on cardboard, metal and plastic: People may acquire coronavirus through air and by touching contaminated surfaces. ScienceDaily. Retrieved April 4, 2020 from www.sciencedaily.com/releases/2020/03/200320192755.htm.
• Van Doremalen et al. (2020, March 17). Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. New England Journal of Medicine. Retrieved 4 April 2020 from https://www.sciencedirect.com/science/article/pii/S0896841120300469?via%3Dihub.
• World Health Organization [WHO]. (2020, February 28). Report of the WHO-China joint mission on coronavirus disease 2019 (COVID-19). Retrieved 4 April 2020 from https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf.
• WHO. (2020, March 18). Basic protective measures against coronavirus. Retrieved 2 April 2020 from https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public.
• WHO. (2020, March 29). Vías de transmisión del virus de la COVID-19: repercusiones para las recomendaciones relativas a las precauciones en materia de prevención y control de las infecciones [Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations]. Retrieved 3 April 2020 from https://www.who.int/es/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations.
• Woodward, A. (2020, April 3). It's estimated 1 in 4 coronavirus carriers could be asymptomatic. Here's what we know. Science Daily. Retrieved 4 April 2020 from https://www.sciencealert.com/here-s-what-we-know-so-far-about-those-who-can-pass-corona-without-symptoms.
//by Angelia Albao and James Tolosa
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