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SARS-CoV-2 and the pandemic of COVID-19

To understand the concept of prevention against COVID-19, it is important to understand the transmission of SARS-CoV-2. It must be emphasised that COVID-19 is a new disease and we are still learning about how it spreads. Evidence suggests that SARS-CoV-2 transmission to humans can occur by three methods—(a) Droplet spray in short range, (b) Fomite (contact) transmission and (c) Aerosol in long range.44 Droplet spray is generated when an infected person coughs, sneezes or even talks loudly and can be infective to others in close contact up to 6 feet(1.8 m). Some experts believe that this distance of 6 feet may not be safe enough a distance to prevent the spread of the virus.45 Often, the virus spreads through fomites when an infected person contaminates the object and gets picked up unwittingly by a new person who gets infected. According to a study on aerosol and surface stability of SARS-CoV-2 published in New England Journal of Medicine, SARS-CoV-2 remains viable in aerosols for at least 3 h, and stable on most objects like plastic (72 h), stainless steel (48 h), cardboard (24 h) and copper (4 h) for long durations.46 The reproduction number (R0), or the number of people catching the disease from one infected individual was initially thought to be between 2.2 to 2.7.47 However, emerging evidence based on the doubling time of 2.4 days during early phases of the epidemic suggests that SARS-CoV-2 could have been more contagious than initially estimated with an R0 value between 4.7 and 6.6.48 This could be attributed to the high number of asymptomatic and mild cases who can unknowingly transmit the infection.

Preventive strategies advocated at administrative level has varied between countries. WHO has repeatedly urged governments to pursue contact tracing as the backbone of COVID-19 response in every country. Countries that have worked hard on contact tracing in the early stages of the pandemic like China, Singapore, South Korea and Germany along with early lockdown of activities have shown a far lower death rate than countries that did not like the United Kingdom and USA.49 Self-isolation for 7 days if a person gets infected or 14 days if anyone in the family shows symptoms of infection has been suggested by the National Health Service, United Kingdom.50 Existing evidence, however, also shows that a period of 7–14 days may not be enough as patients can continue to shed the virus up till 37 days, as evidenced from a study in China that showed the mean duration of virus shedding to be 20 days.51 Washing hands with soap and water for at least 20 s, avoiding touching eyes, nose or mouth if the hands are not clean, frequent use of hand sanitisers, washing hands on return to home, covering of mouth and nose with tissue or sleeve while coughing or sneezing and immediate washing of hands afterwards has been recommended by the National Health Service to control the spread of infection.52 Few countries have also advised public to wear face masks or cover the mouth and nose with scarves and bandanas to prevent spread of infection, reserving respirators and medical masks for healthcare use.53 In spite these efforts, new infection rate was found to be rising at alarmingly high levels globally which is why the government of most countries had to impose a national lockdown of unnecessary activities to prevent community spread of infection with the aim to reduce R0 to less than 1.

It has been suggested by most authorities that the real victory over COVID-19 can be achieved by mass vaccination that would produce herd immunity in the population. There is an ongoing speculation on when a safe vaccine would be ready for mass administration, with some authorities suggesting that it may take up until 18 months while others claiming it would be available by the autumn of 2020. More than 100 trials are ongoing in different countries, out of which the USA, United Kingdom and China are among the few countries to began with human trials. In the United Kingdom, the University of Oxford’s Jenner Institute and Oxford Vaccine Group have begun recruitment for a human trial on the vaccine, ChAdOx1 nCoV-19, which is based on a harmless chimpanzee adenovirus genetically engineered to contain the S-protein of SARS-CoV-2 [ClinicalTrials.gov Identifier: NCT04324606].54

Another potential therapy that is being investigated in trials is the effect of convalescent plasma of patients who have recovered from SARS-CoV-2 infection. This is based on a few studies that showed promising results with convalescent plasma containing anti-COVID antibodies when transfused to patients suffering from severe COVID-19.55

It is very difficult to predict the direction of the SARS-CoV-2 pandemic. It remains to be seen if the disease will largely disappear like SARS-CoV and MERS-CoV or if it will continue to exist in the community with repeated outbreaks in future. The global health community is dealing with the brunt of the pandemic and many healthcare workers have sacrificed their lives treating patients with COVID-19. More than a hundred healthcare workers have died in this pandemic in the United Kingdom.56 According to a few countries, 5–15% of all reported infections have been among healthcare workers caring for these patients.57 Many of these healthcare workers have caught the infection in the line of duty due to shortages of personal protective equipment (PPE) due to under-preparedness by different governments in anticipating the crisis, often paying the price with their lives. Once the peak has passed and flattening of the curve is achieved, the number of new cases and deaths are expected to reduce in numbers. However, the real chance of preventing further peaks and future outbreaks is essentially going to require the development of an effective antiviral strategy like vaccines (preventive) and drugs (therapeutic) that can act on SARS-CoV-2, hence reducing the clinical sequelae of an infection and this is something which the scientific community worldwide should focus on. Being prepared for another future pandemic of this proportion is also worth mentioning and prompt action by the government in early phases of the transmission with contact tracing along with stockpiling necessary PPE in advance for the healthcare workers could help contain the pandemic with far lesser consequences than COVID-19.

Self-assessment questions

1) Which of the following is true of COVID-19?

A) It is caused by the SARS-CoV-2 virus.

B) It was first identified in Italy.

C) Genetic analysis of the virus shows a structural resemblance to bat coronavirus.

D) The disease primarily affects the kidneys with the respiratory system affected as the second most common organ system.

2) Severe COVID-19 is characterised by—

A) Respiratory rate of >30 breaths per minute.

B) Prognosis is worse in children compared to age >60 years.

C) Prognosis is worse in patients with BMI <35 compared to BMI >35.

D) Loss of smell and taste suggests severe disease.

3) Diagnostic criteria for COVID-19 includes-

A) Antibody ELISA is the gold standard test for diagnostic confirmation of COVID-19.

B) Chest X-ray is confirmatory is almost all positive cases.

C) CT chest can show features of ground glass opacity, consolidation and fibrosis.

D) Lymphopenia alongside neutrophilia is characteristic.

4) Regarding treatment of COVID-19—

A) Critical patients can be successfully treated with hydroxychloroquine in all cases.

B) Invasive ventilation can be viewed as a good prognostic sign due to better respiratory support.

C) LOTUS trial failed to show any significant clinical improvement with lopinavir-ritonavir combination.

D) RECOVERY trial testing a range of potentially different treatment options is a major drug trial on COVID-19 in the United States of America.

5) Transmission of COVID-19 can be reduced by—

A) Frequent hand washing with soap.

B) Maintaining sufficient distance from other people (social distancing).

C) Prophylactic antibiotics.

D) Visiting crowded areas like supermarkets and gym instead of open spaces like park.

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