A Spotlight on COVID-19 Contact Tracing

1. <jiIntroduction

The Coronaviruses (CoVs) almost ruled out the year 2020 with an outbreak of the pandemic disease named COVID-19.  These novel coronaviruses are a diverse group of viruses that caused enough damages to the world since 2002. This blog addresses the origin, history, signs and symptoms, and the effects of COVID-19. It also emphasizes on different terminologies like incubation and infectious periods, and its diagnosing methods to prevent the transmission of COVID-19. The main essence of this blog is to identify and investigate the COVID-19 cases and their contacts. The final step in this contact tracing process is to calculate the isolation and quarantine duration to prevent COVID-19 transmission.

COVID – 19 and its history

The coronavirus is named so, as it seems like having a crown around it, and is derived from ‘corona’ (Latin word) meaning crown (Fig.1). There are many different coronaviruses, they generally infect mammals and birds which show respiratory illness as a common symptom. So, coronaviruses are not new but the virus that causes COVID-19 (COronaVIrus Disease 2019) is.

SARS–Cov-2

The virus that creates COVID-19 is a novel SARS -2 (Fig. 2) coronavirus and it is originated in bats. These novel coronaviruses developed in bats have the ability to jump between species and infect people, and then it developed another very special coronavirus to be able to be transmitted between people, and that is how it came to cause the pandemic that we are experiencing now. So, this kind of trick that the coronaviruses have isn’t new. This is the third coronavirus that did the same since 2002. The worst of these viruses was SARS-CoV (Severe Acute Respiratory Syndrome) emerged in China, in 2002, and the next of this kind was MERS-CoV (Middle Eastern Respiratory Syndrome) materialized in the middle east in 2012, and still causes human infections and small outbreaks. Of late, at the end of 2019, SARS-CoV-2 materialized in Wuhan, China.

Figure 2 SARS-CoV-2 viruses coming out of a cell
Photo credit: US National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories (NIAID-RML)

What happens to people if they get infected?

The important thing to notice here is, not everyone who is infected gets sick. If anybody infected with SARS-CoV2, the possible common signs (measurement to confirm illness) and symptoms (what patients say about how they feel) are:

• Fever >100.4˚F
• Fatigue (tiredness)
• Muscle ache
• Chills
• Cough
• Difficulty breathing
• Sore throat
• Headache
• Loss of taste and smell

Some people have mild symptoms, some have no symptoms and they are known as “Asymptomatic”. Some may have a very serious disease that leads to death.

There some severe signs and symptoms of progressive infection for which patients should seek emergency medical care, and they are:

• Bluish lips or face
• Increased rate of breathing
• Shortness of breath
• Chest pain or pressure when breathing
• Waking up during sleep with shortness of breath
• New confusion or difficulty waking up

Effect of COVID-19 on the lungs

As COVID-19 attacks mainly the respiratory system of humans, it replicates inside and creates breathing trouble. Figure 3 shows the difference between healthy and severely infected lungs.

Figure 3 Healthy (left) and severely infected (right) lungs. Photo credit:  Left: Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org, rID: 8095. Right: Case courtesy of Dr. Fabio Macori, Radiopaedia.org, rID: 74867

Timeline of COVID-19 Infection

This timeline consists of incubation and infectious periods of those who get infected from COVID-19 positive cases.

Incubation period

It is the time duration from when someone is infected until the symptoms develop. Normally, the incubation period ranges from 2 to 14 days. 50% of people become ill within 5 days of infection. Figure 4 explains the incubation period.

Figure 4 Incubation period for COVID-19 Image adapted by Center for Teaching and Learning, Johns Hopkins Bloomberg School of Public Health, from Bi, Q., et al. (2020). Epidemiology and transmission of COVID-19 in Shenzhen China: analysis of 391 cases and 1,286 of their close contacts [medRxiv preprint]. Infectious Diseases (except HIV/AIDS). https://doi.org/10.1101/2020.03.03.20028423

Infectious period

It’s the time period when the infected person can transmit the virus to other people. It’s very pathetic to know that, the infectious period begins 2 days before the signs and symptoms start. By this time, even the patient doesn’t aware that they are transmitting the disease. The end of the infectious period may be defined as when,

• It is at least 10 days of onset of illness, and
• Symptoms are improving, and
• No fever for the past 3 days

Note: Asymptomatic people can also be infectious.

Figure 5 details the incubation and infectious periods for COVID-19 patients.

Risk factor

This is the factor that defines those who are more likely to get infected very easily.

Older age and obesity people

The people of age groups > 65 years and who are obese have more chance to get infected.

Death is more common for the following cases,

• 65 to 75 years old, 2% to 5% die
• 75 to 85 years old, 4% to 10% die
• Of those >85 years old, >10% die
• Even, some young healthy people become severely ill whereas children are very unlikely to be seriously ill.

Figure 5 Timeline of incubation and infectious period
Image source: Center for Teaching and Learning, Johns Hopkins Bloomberg School of Public Health

Treatment for COVID-19

Till now, there is no specific treatment or vaccine to cure COVID-19. The only possible way is to increase the body’s immune system that can fight the infection. People with lung disease should require mechanical ventilation to breathe during infection.

Diagnosing COVID-19

In order to find whether a person is infected or not and the level of infection, two methods are in practice and are as follows.

Diagnosing tests

It identifies the virus in the body through ‘Polymerase Chain Reaction’ (PCR tests). It detects the RNA of the virus and confirms that SARS-CoV-2 is reproducing in cells. To identify this, a swab is taken from the nose, throat (respiratory tract) or mouth (saliva)

Antibody tests

This method is used to identify the antibodies (IgG) to the virus if any, developed in blood. This IgG begins to develop in patient’s blood during sick (which fights against viruses) and can only be identified after recovery.

Investigating Cases and tracing their Contacts

Once the patient is tested positive (case) for COVID-19, the health officials follow six steps to follow cases and their contacts.

The patient who is confirmed positive for COVID-19 is a ‘Case’ and the people who were in close contact with the case are ‘Contacts’.

Steps to be followed during the investigation

There are 6 such steps and are:

• Introduce                                             – to get basic information about the case
• Inquire                                                 – to know his/her’s likely infectious period
• Identify contacts                                – ask for contacts during the infectious period
• Isolate case                                          – provide isolation instructions
• Initiate contact tracing                     – call contacts ask for signs and symptoms
• Implement regular check-ins          – until isolation or quarantine ends

Isolation and Quarantine

Isolation

People who are tested positive and with severe symptoms should be admitted immediately in hospitals. People with no symptoms but tested positive have to isolate themselves from other members of the family for incubation and infectious periods till recovery.

Quarantine

The contacts who had close relationships with the case, like family members, office collogues, nurses, etc. must quarantine themselves for at least 14 days or until they recover.

Conclusion

The SARS-CoV-2 is one of the coronaviruses that cause deadly disease COVID-19. This blog addresses the signs and symptoms of COVID-19 and its effect. The timeline of COVID -19 infection includes the incubation and infectious periods. It also emphasizes when the cases and their contacts should go for isolation and quarantine respectively. It is the prime duty of health officials to have regular check-ins with traced conctacts.

Reference

1. A one-week online course on “COVID-19 Contact Tracing” jointly offered by Johns Hopkins University, Maryland, USA, and Coursera by Emily Gurley, Associate Scientist, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health.