COVID-19: Outbreaks, impact on society and potential solutions

Are you fully informed about the features of COVID-19, its detection, and the future potential approaches for the development of vaccines? Get a detailed and graphically illustrated analysis of the virus made by Manlio Fusciello, PhD student working at the Division of Pharmaceutical Biosciences & Drug Research Program at the University of Helsinki.

The latest global coronavirus outbreak that the entire planet has been experiencing since the end of last year has radically changed our view of the world and has affected people’s everyday lives. Acute respiratory syndrome coronavirus 2 (SARS-CoV-2), commonly known as COVID-19, has led to restrictions, quarantines, curfews and many other limitations mainly on social activities and personal interactions because the medical and scientific community has so far been unable to eradicate it. Country lockdowns and restricting physical contacts between potentially infective individuals seemed to be the best way to slow down and stop the virus from spreading exponentially.

It seems the virus originated from bats and was transmitted to humans through unknown intermediary animals in a street market in Wuhan, Hubei province, China in December 2019. Since that time, this coronavirus has shown the world how easily a spillover event might happen and how quickly a virus can spread throughout the world, affecting society and having a major impact on global healthcare and the economy.

Despite the fact that the world was unprepared for the outbreak due to a lack of vaccines and antiviral drugs against this virus, scientists and medical personnel are reacting swiftly to bring things back to normal. At the moment facing the emergency on the front line by means of detection, assistance and support for infected patients is the best option while vaccine solutions are investigated. Here we analyze the features of this coronavirus, its detection and future potential approaches for the development of vaccines.

Introduction

Outbreaks are not new to us and have had major impacts on society in the past. In the history of epidemics, we can recall several situations similar to the present one, such as yellow fever, smallpox, human immunodeficiency virus, influenza, Ebola virus, Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS) and few more.

Viruses have evolved to coexist with the host they preferentially infect, meaning that killing the host is always an unwanted side effect. Normally, a virus binds to the cell surface through an interaction with a specific receptor, enters and uses the cellular machinery to self replicate and produce more copies of itself. The new viral copies cause the cell to burst and eventually infect cells located nearby. In fact, the present and past outbreaks such as influenza, MERS and SARS are classified as spillover phenomena, where a virus originally infecting an animal species can “jump” and evolve to infect humans. Being the new host in a new environment, before the virus is able to adapt to the new individual, its mechanism of replication might create problems for the host’s physiological functions.

COVID-19 infection affects people differently. Most patients seem to be asymptomatic while others experience common flu-like symptoms such as fever, cough, sore throat, breathlessness and fatigue. In the elderly, COVID-19 in conjunction with other pre-existing conditions provokes a local overreaction of the immune system in the lungs resulting in pneumonia, generating acute respiratory distress syndrome (ARDS) and multi-organ dysfunction leading to eventual death.

COVID-19 detection

When a patient shows typical respiratory symptoms, a precise diagnosis is needed to discriminate a potential COVID-19 infection from other infections or unrelated viral respiratory diseases. The diagnosis uses advanced molecular tools to study the genetic information of the virus (RNA) in the cells of the respiratory tract. Cells present in the nose, mouth, throat and accessible respiratory tract-related areas are collected by means of a swab and the RNA present into the cells is isolated. Once purified, the RNA needs to be converted to DNA using quantitative Polymerase Chain Reaction (qPCR) techniques, which reverse the RNA and quantify the amount of viral presence, as shown in Figure 2.

To understand if an individual has encountered a specific pathogen and has recovered from the resulting infection, a serological diagnostic test is performed using peripheral blood in an assay called enzyme-linked immunosorbent assay (ELISA). Blood is simply processed for an easy detection to hunt for antibodies that have been produced in response to the recognition of COVID-19 by the host’s immune system. Those antibodies bind to the recognized COVID-19 antigens marked with gold particles (Figure 3). If this bond proves to be positive, the test will show a band displaying the detection of antibodies that are able to recognize the virus. Once isolated and purified, these antibodies can be used as therapy.

Precautions and behaviour

Thus far, no antiviral drugs or vaccine against COVID-19 have been approved for therapeutic purposes. The Center for Disease Control (CDC) and the World Health Organization (WHO) have therefore issued guidelines on how to reduce viral spread. In addition to the major restrictions being placed on reduced physical interaction, most preventive guidelines rely on common sense and new habits to be implemented in everyday life.

Since the disease spreads through the inhalation of viral particles present in the droplets exhaled by breathing, wearing protective masks reduces the likelihood of coming into contact with the pathogen. Another vital route to infection is direct pathogen transmission, especially via the hands, between people or between people and objects, thereby highlighting the importance of adequate hand hygiene. Hence, regular and careful hand washing using soap or any alcohol-based detergent to inactivate the pathogens present on the skin is another essential way in which people can help to avoid viral exposure.

Development of a vaccine

While for the acute phase of the disease the medical and scientific community is trying to repurpose several drugs used for other RNA viruses or malaria and at the same time isolating the antibodies from cured patients and administer them to new patients, a long-term solution in the form of a vaccine is urgently needed. Scientists around the world are constantly working on ways to produce an effective vaccine that can be quickly mass produced and distributed. The development of a vaccine considers several approaches to finding a long-lasting therapy using the protection provided by the host’s own immune system.

The principle behind vaccination is to generate memory cells, which will release neutralizing antibodies against the virus when the pathogen invades the host. Another purpose of vaccines is to generate anti-viral cytotoxic lymphocytes capable of destroying infected cells while the virus is in its replication cycle. The most effective approaches are those that use live attenuated pathogens which, being live, are able to replicate but not able to induce any disease. Some other methods utilize dead pathogens or parts of them since their immunogenicity lies in their structure rather than in their activity. More advanced vaccination techniques are based on identification of peptides (protein chunks), which the immune system can spot and use to recognise viral infected cells. A few interesting approaches involve artificial viral vectors working as specific carriers of viral DNA, mRNA (this information will then be translated into a protein resembling the virus) and peptides using healthy cells as a ‘training camp’. In the end, our own immune system, if well trained, will protect us and bring the situation back to normal.

Source of the explanatory images: Biorender