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Viral Infections - A Modern Pandora’s Box

Over the past week, terms like ‘social distancing’ and ‘self -quarantine’ have become common parlance. Apprehension is escalating about COVID 19 and mandates to cancel events, work from home, schools being closed, staying away from congregations and so on, are gaining momentum. It is frightening for all, as families worry about loved ones around the world, brood about the economic impact on their lives and there is a growing sense of helplessness.

Alongside, there is a glimmer of positivity. As I started work on this article, three out of four coronavirus patients in Jaipur, Rajasthan were cured with a novel combination of medicines.

VIRUS is an infectious agent, whose name originated from the Latin word meaning ‘simply fluid’ or ‘poison’. They are not true organizms because they lack the machinery and organization of life form, instead, they wholly depend on other living cells for their processes.

As these viruses lack cellular structure and remained obligate parasites, they were thought to be primordial life forms, but recent cancer studies on proto-oncogenes strengthened the fact that viruses were simply rogue genetic material. The degraded DNA or RNA material, not repaired by cellular mechanisms could have evolved to become viruses. Though the viruses depend on the host for metabolism and replication, they rapidly infect other cells and spread to different animal hosts despite containment measures, hence the phenomenon of something spreading rapidly is aptly termed ‘Viral’.

The viral genetic material mutates while replicating in the host cell and this enables the viral infections to be unaffected by an immune response. The host immune system learns from infection and produces antibodies against that particular offending pathogen. The response elicited against one particular strain of virus may not be efficient against another strain of a virus causing the same disease. This will become more significant in cases where the virus affecting humans have animals such as bats, pigs, wild birds as an intermediate host. In a scenario where the infection is simultaneously affecting different animal species, the human population will have little or no immunological protection against the new virus, which will result in a pandemic like COVID-19. The hypervariable genetic segments of the viruses resulting from mutations make synthesizing a vaccine for the recent SARS-CoV-2 is still a daunting task.

COVID-19

Coronavirus disease has been abbreviated as COVID-19 and the causative agents is a virus called severe acute respiratory syndrome coronavirus 2 abbreviated as SARS-CoV-2.  This belongs to the coronavirus family identified in the 1960s, which has subtypes like alpha, beta etc. among which the beta subtypes id further classified into four more types. Mutations in viruses of the coronavirus family were responsible for two other major international outbreaks in modern history, the SARS outbreak of 2003 resulting in around 800 deaths and the MERS outbreak in 2013 claimed about 900 lives. With the COVID-19 virus, it is believed to have mutated from bats which are animal hosts and passed on to pangolins which were intermediate hosts. Multiple mutations which are generally accepted as chance events occur in the virus that enabled them to affect humans and manifest as severe disease. My country, India suffered a Nipah virus outbreak in 2018 which had a case fatality ratio of about 75% claiming more than 495 lives. The mortality rate for SARS is about 10% and for MERS remained at 34%. So as compared to these, the mortality rate in COVID-19 has been considerably less, at about 3.4% while the total number of cases is greater than 1,13,700. However, another concerning factor leading to the rapid spread of SARS-CoV-2 is the infectivity of this virus which is in the range of 1.5 to 2.5. Infectivity of an organism is the ability by which it can spread from one human host to the other, by way of transmission, which is measured as R0. For measles, the Ris about 12-18, for chickenpox, it is about 6 and for the regular seasonal flu, R0 is about 1.5.  While COVID-19 and flu have similar infectivity, the mortality rate of flu is significantly low at 0.02%, and the lasting damage leading to hospitalization is lower compared to COVID-19. 

Furthermore, unlike envisaged earlier, the incubation period of COVID-19 is thought to be as long as 2-14 days compared to the 3-5 days observed in flu. This is vital to know because asymptomatic people can silently transmit the disease to others without even knowing. Among all infected people, 81% will have the mild form of the disease while 14% may suffer from severe forms requiring hospital admission with measures like O2 support, symptomatic relief etc and 5% cases are severe forms which can progress to severe forms of pneumonia, needing ICU care with assisted mechanical ventilation.  Critical cases include patients who suffer from respiratory failure, septic shock, and/or multiple organ dysfunction or failure. Severe cases include patients who suffer from shortness of breath, respiratory rate ≥ 30/minute, blood oxygen saturation ≤93%, PaO2/FiO2 ratio <300,28 and/or lung infiltrates >50% within 24–48 hours.


It is important to note that despite having low mortality rates, death among the elderly is significantly high, especially above the age of 80 years the mortality rate is at 15%. People with pre-existing medical conditions like diabetes, hypertension, heart diseases and lung illness are at a higher risk of suffering serious damage if they contract the disease. Smokers can easily contract the disease and suffer more damage than non-smoking individuals. Above all, understanding the evolution of the disease is key to instituting containment and prevention strategies. Testing identifies affected cases and gives objective data to incorporate countermeasures in controlling the spread and justification for containment measures such as isolation and quarantine.

Early counter measures intend at lowering the peaking of disease spread within the community, limiting the demand on the healthcare system. In epidemiological terms slowing the spread of an infectious agent is called “flattening the curve”, where the curve refers to the projected number of people who will contract COVID-19 over time. A steep curve signifies rapidly increasing numbers of people with the disease which can overwhelm the local health care system. The flatter the curve, the same number of people inevitably get infected but the occurrence is spread over a longer time frame, not overloading the health care system beyond its capacity. This model called the Drew Harris curve, after the population health researcher, was seen working during the Spanish flu outbreak of 1918. When comparing two cities in the U.S, Philadelphia where the city officials ignored the early warning about the spread of the disease and St. Louis, where the city officials quickly implemented social isolation strategies. Ultimately Philadelphia lost 16,000 of its inhabitants over St. Louis lost only about 2,000 people – one-eighth of the casualties of Philadelphia over the same span.

World Health Organization describes the symptoms based on the 50 thousand plus laboratory-confirmed cases of COVID-19, amongst whom fever and dry cough have been the most common symptoms. The third most common symptom is fatigue, and 1 in 5 patients experienced shortness of breath. 3-5% presented with diarrhoea, which can be risky in the elderly if not treated. While sharing a lot of common symptoms with flu, runny-nose was rarely seen in patients with coronavirus infection. On average, this disease can last up to 2 weeks in mild cases while the same study suggests that it may take 4-6 weeks for severe cases to recover. Critical cases have a varied time of recovery depending on the individual’s health status.

Prevention Strategies

Aggressive testing and disease identification, Quarantine measures, deploying right equipment and staff training are the chief measures in containing any pandemic, let alone COVID-19. Given the lack of vaccination, the limited success of antiviral drugs and the availability of ventilators, non-pharmaceutical interventions are likely to dominate the public health response to a pandemic of this magnitude. Public health measures from relatively innocuous techniques, such as disease surveillance and hygienic measures, to considerably more restrictive interventions, such as social distancing, travel restrictions, quarantine, and case isolation are warranted for containment. The hope is that public health interventions, while incapable of completely stopping the transmission of the virus, will be able to slow the pandemic granting time to the health care system to cater for all the patients.

Surveillance is necessary to quickly identify and respond to the COVID 19 as witnessed in South Korea. It had the largest prevalence in Asia other than China, where the incidence rate has been brought down to near zero. When comparing the trajectories of confirmed cases growing versus time, Singapore witnessed the lowest incidence thanks to the strict preventive and prohibitive measures. Surveillance thus comprises a crucial element of the early response to a forming pandemic.  As these measures involve governments collecting sensitive health information from patients, travellers, migrants, and other vulnerable populations, surveillance also poses privacy risks.

Screening and testing while helping to limit the spread of the disease, can pose serious threats to a person’s privacy and bodily integrity. Ideally, public health officials should receive an individual’s informed consent before performing any medical tests, and education programs can help convince many people to agree to voluntary testing. Hygienic measures to prevent the spread of respiratory infections include hand-washing, disinfection, the use of personal protective equipment (PPE) such as masks, gloves, gowns, and eye protection, and respiratory hygiene, such as the use of proper etiquette for coughs, sneezes, and spitting. The public must be informed of the need for hygienic measures as misinformation has been rampant during the past pandemics. The situation raises issues of distributive justice because ineffective or inaccurate communications have the greatest effects on marginalized members of society, as they are the least likely to have access to alternative credible sources of information. Health care professionals and organisations should focus on educating people with the right information and build a good public partnership as a way of achieving adherence. The information disseminated through public education campaigns should be accurate, clear, uncomplicated, not sensationalistic or alarming, and as reassuring as possible.

Our experience from other pandemics shows that one consistent response to epidemics has been to decrease social mixing and increase social distancing by means such as community restrictions and voluntary social separation which have been effective to an extent in limiting the spread and slowing the advance of the disease by local transmission. Governments should explicitly define who has the power to order social distancing strategies and for what period as there is a worry that governments might use social distancing in a discriminatory fashion, scapegoating ethnic or religious minorities, or might deploy social distancing as a pretext to crack down on dissidents who assemble to protest.

Isolation and quarantine are two of the oldest disease-control methods in existence and they have been deployed during this COVID-19 pandemic. While the terms “quarantine,” “isolation,” and “compulsory hospitalization” are often used interchangeably, they are, in fact, distinct. The definition of quarantine is the restriction of the activities of asymptomatic persons who may potentially have been exposed to a communicable disease, during or immediately before the period of communicability, to prevent further chances of disease transmission. In contrast, isolation is the separation, for the entire period of communicability of the infecting agent, of known infected persons in such places and under such conditions as to prevent or limit the transmission of the infectious agent.

Quarantine and isolation can be accomplished by various means, including confining people to their own homes, restricting travel out of an affected area, and keeping people at a designated facility such as a hospital, exclusively equipped camp. Pulling through a pandemic such as COVID-19 forces any society to face several difficult challenges, many of which transcend the issue of mere scientific effectiveness.

The threat of COVID- 19 pandemic is real, but it is conquerable. As a silver lining in the darkness shrouding our nation and the world, the news of doctors from Jaipur’s Govt. hospital treating three confirmed patients successfully offers some great hope. Two of those patients were elderly with comorbid conditions which put them at a higher risk. But a novel drug therapy combination rendered them cured as their tests were negative for COIVD-19. Standing together as a nation in these tough times and adhering to disciplined self and surrounding hygiene habits, putting our trust in our healthcare system to treat us and investing in preventive care for the future can make our resilient nation march past such tribulation.

http://blog.ficci.com/archives/8521

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