Covid-19

Published: 10 Jul 2024, 10:45 AM

Medically Reviewed by

Dr Sushila Kataria

What is Covid-19?

Causes of Covid-19

Coronaviruses are zoonotic. This means it was first developed in animals before being transmitted to humans. The virus is transmitted from animal to human when a person comes into close contact with an infected animal. After the virus develops in humans, coronaviruses can spread from person to person. According to the Centers for Disease Control and Prevention (CDC), Covid-19 primarily spreads in three ways:

• Inhaling air near an infected person who exhales small droplets containing the virus.
• Direct contact with these droplets landing on the eyes, nose, or mouth.
• Touching surfaces contaminated with the virus, then touching the eyes, nose, or mouth.

While surface transmission is possible, the CDC suggests it is not the primary mode of Covid-19 spread. Importantly, individuals infected with Covid-19 can transmit the virus to others, even if they do not show symptoms. Generally, closer and longer interactions with others pose a higher risk of Covid-19 transmission.

Risk factors

Many individuals infected with Covid-19 recover at home, but for some, the virus can cause severe illness. Hospitalization, intensive care treatment, or breathing help may be necessary. Unfortunately, severe cases can even lead to death. While not all risk factors are fully understood, those most vulnerable to contracting Covid-19 include:

• Live in or have recently visited an area with active transmission.
• Close contact with someone confirmed or suspected to have Covid-19, defined as within 6 feet for a total of 15 minutes or more over 24 hours.
• Exposure to infected saliva presents a high risk of infection.
  
• Individuals over 60 years old with a weakened immune system.

Apart from these factors, Covid-19 risks also include severe medical complications such as:

• Heart diseases (such as coronary artery disease-CAD)
• Diabetes mellitus (both type 1 and type 2)
• Chronic lung disease (such as asthma, or chronic obstructive pulmonary disease-COPD)
• Chronic kidney disease (especially if you are on dialysis)
  
• Liver disease (like cirrhosis)
  
• Sickle cell anemia
  
• Obesity
  
• Cancer
  
• HIV (human immunodeficiency virus)

Additionally, being unvaccinated or not up to date on Covid-19 vaccinations also increases the risk of severe Covid-19 outcomes.

Other risk factors for severe Covid-19 are:

• Not getting enough physical activity
• Smoking
  
• Pregnancy or having recently given birth
  
• Use of medicines that lower the immune system’s ability to respond to germs

Also, disability is linked to an increased risk of severe Covid-19. However, the risks are different depending on the disability.

Covid-19 and pregnancy

Pregnancy increases the risk of complications from Covid-19, according to the CDC. Pregnant women are more susceptible to severe illness compared to nonpregnant women and have a higher likelihood of preterm birth when infected with Covid-19. While transmission of the virus from mother to fetus during pregnancy is uncommon, newborns can contract the virus post-delivery.

Pregnant women must take precautions to minimise exposure to the virus, which includes practicing good hygiene, wearing masks in public places, and getting vaccinated against Covid-19 to protect themselves and their babies. Moreover, monitoring symptoms closely and seeking medical advice if symptoms develop is recommended.

Key Facts About Covid-19

Major Symptoms	Fever Chills Cough Loss of sense of taste or smell Fatigue Shortness of breath or difficulty breathing Muscle and joint pain Sore throat Stuffy or runny nose Headache Nausea/vomiting Nasal congestion Gastrointestinal symptoms such as diarrhoea, nausea, and vomiting
Necessary Health Tests	Polymerase chain reaction (PCR) testing Antigen testing Self-test or at-home test
Treatment	Mild cases: Mild cases typically require rest, adequate hydration, and over-the-counter medications to alleviate fever and pain. Moderate cases: Patients with moderate symptoms may need oxygen support for respiratory function. Hospitalisation may also be required for close monitoring and additional medical care. Severe cases: Severe Covid-19 cases may demand intensive care and advanced respiratory support, such as mechanical ventilation, to maintain vital functions.

Symptoms of Covid-19

Covid-19 symptoms vary depending on the type of variant contracted, ranging from mild symptoms to a potentially fatal illness. The symptoms typically manifest within 2 to 14 days after exposure, with most appearing around 5 days later. Remember, an infected person can spread the virus even without symptoms. Here are the common symptoms of Covid-19:

• Fever
• Chills
• Cough
• Loss of sense of taste or smell
• Fatigue
• Shortness of breath or difficulty breathing
• Muscle and joint pain
• Sore throat
• Stuffy or runny nose
• Headache
• Nausea/vomiting
• Nasal congestion
• Gastrointestinal symptoms such as diarrhoea, nausea, and vomiting

This is not a complete list of all potential symptoms. Symptoms may evolve with new variants of the virus, and individuals may experience some, all, or no symptoms whatsoever. Additionally, symptoms can differ based on vaccination status and whether one has received a booster shot. More severe symptoms that require seeking medical help right away include:

• Trouble breathing
• Chest pain or pressure that persists
• Confusion or inability to wake up
• Blue lips or face

Any other severe symptoms that concern you

Covid-19 vs flu (Influenza)

Covid-19 and influenza (flu) share many similar symptoms, such as cough, runny or stuffy nose, sore throat, fever, headache, fatigue, chills, and body aches. Due to these overlapping symptoms, it can be challenging to distinguish between the two based on symptoms alone. Here’s what can help you understand the difference between Covid-19 and the flu:

• Both Covid-19 and the flu are contagious respiratory illnesses, but they are caused by different viruses. Covid-19 is caused by infection with the coronavirus SARS-CoV-2, which was first identified in 2019. In contrast, the flu is caused by influenza viruses.
• One key difference is their transmission and severity. Covid-19 tends to spread more easily than the flu and can cause more severe illness in some individuals, leading to higher rates of hospitalisation and mortality compared to influenza.
• Another distinguishing factor is the incubation period and duration of contagiousness. People infected with Covid-19 may take longer to show symptoms after exposure (typically 2-14 days) and can be contagious for a longer period of time compared to those with the flu.
• Testing for Covid-19 and influenza also differs. Specific tests are used to detect each virus: PCR (polymerase chain reaction) tests are commonly used to diagnose Covid-19, while rapid antigen tests can be used for both Covid-19 and influenza. Testing is crucial for accurate diagnosis and appropriate management of these illnesses.

Covid-19 variants

One thing we all know about SARS-CoV-2, the virus responsible for Covid-19, is that it is changing constantly, resulting in different variants. Mutation is a natural process, where some mutations fade away while others persist. Certain mutations, like those seen in the Delta and Omicron variants, may even enable the coronavirus to spread faster from person to person. Since the start of the pandemic, notable variants have included Alpha, Beta, Gamma, Delta, and Omicron.

• Alpha (B.1.1.7): The first variant, which was first reported in the United Kingdom (UK) in late December 2020
• Beta (B.1.351): First reported in South Africa in December 2020
• Gamma (P.1): First reported in Brazil in early January 2021
• Delta (B.1.617.2): First reported in India in December 2020
• Omicron: First reported in South Africa in November 2021 and it has spread to more than 57 countries

On December 19, 2023, the World Health Organisation (WHO) identified another significant variant, JN.1, as a variant of interest.

Diagnosis of Covid-19

Diagnosing Covid-19 typically involves several methods that use samples such as blood, saliva, or respiratory tissues. These tests aim to detect genetic material or specific proteins associated with the SARS-CoV-2 virus, which causes Covid-19.

1. Polymerase chain reaction (PCR) testing

This is the most common and accurate method for diagnosing Covid-19. This test detects the genetic material of the SARS-CoV-2 virus (the virus causing Covid-19) from a respiratory sample (usually obtained via a nasal or throat swab). The results may take up to 3 days, depending on the testing location and demand.

2. Antigen testing

Antigen tests are rapid tests that detect specific proteins on the surface of the virus. They are quicker than PCR tests and can provide results in about 15-30 minutes. These tests are also conducted using nasal or throat swabs. However, in general, antigen tests are less likely to detect the virus than PCR tests, especially when symptoms are not present. Therefore, a single negative antigen test cannot rule out infection. To be confident you do not have Covid-19, the Food and Drug Administration (FDA) recommends 2 negative antigen tests for individuals with symptoms or 3 antigen tests for those without symptoms, performed 48 hours apart. A single PCR test can be used to confirm an antigen test result.

3. Self-test or at-home test

On November 17, 2020, the FDA issued its first emergency use authorization (EUA) for a COVID-19 self-testing kit. This is an antigen test that can be taken anywhere without having to go to a specific testing site. The EUA specifies that the test kit is authorised for use by people ages 14 and older whom healthcare professionals have identified as having suspected Covid-19. Read the instructions written on the self-test package thoroughly and follow the instructions closely when performing the test.

Interpreting your results

Covid-19 test results fall into three categories: positive, negative, or inconclusive. Here’s what they mean:

1. Positive result: Indicates the presence of SARS-CoV-2 genetic material or proteins, confirming an active Covid-19 infection.

2. Negative result: Suggests that the virus was not detected at the time of sample collection. However, a negative result does not completely rule out Covid-19, particularly if symptoms are present or recent exposure to the virus occurred. In such cases, it may be necessary to test again.

3. Inconclusive result: This occurs when the test cannot confirm either a positive or negative result definitively. This might happen due to insufficient viral material in the sample or technical issues. Inconclusive results may require retesting.

What is antibody testing?

Antibody testing involves analysing a blood sample to detect antibodies produced by the immune system in response to SARS-CoV-2 infection. These tests are primarily used to determine whether an individual has previously been infected rather than to diagnose an ongoing infection, as antibodies may take several days to weeks to develop post-infection.

Results: Antibody tests provide insights into how the immune system responds to Covid-19 in recovered individuals. A positive antibody test indicates the presence of antibodies, suggesting some level of immune protection either from prior infection or vaccination. This immune protection may help in fighting off the virus if exposed again but antibody levels can decline over time and it is not clear how long antibody protection lasts.

When should you test for coronavirus (Covid-19)?

You should test for Covid-19 in these 4 circumstances:

• Symptoms: If you experience symptoms associated with Covid-19, including fever, cough, shortness of breath, loss of taste or smell, and fatigue.
• Close contact: If you have been in close contact with an individual diagnosed with Covid-19, especially within the past 14 days.
• High-risk areas: If you reside in or have recently traveled to areas with high rates of Covid-19 transmission.
• Public health guidance: Following public health recommendations or mandates that encourage testing based on local conditions or specific exposure risks.

Prompt testing helps identify the virus early, facilitates timely isolation to prevent further transmission, and provides appropriate medical care for those infected with Covid-19.

How to avoid spreading Covid-19 to others?

If your results are positive, you need to stay home or separate yourself from anyone you live with for as long as you have worsening symptoms to prevent the spread of infection. How long you need to keep yourself isolated depends on your symptoms and health status. Your healthcare professional can advise you on what is best for your situation. Apart from this, keep these tips in mind:

• If you must be around others, maintain a distance of at least 6 feet away whenever possible to reduce the risk of transmission.
• Wear a mask that covers your mouth and nose properly whenever you are in the presence of others, even if you are at home.
• Wash your hands frequently with soap and water for at least 20 seconds. If soap and water are not available, use a hand sanitizer containing at least 60 percent alcohol.
• Steer clear of crowded indoor spaces where the virus can spread more easily.
• Refrain from sharing personal items such as cups, towels, and utensils. Use separate bathroom and bedroom facilities, if possible.
• Regularly clean and disinfect commonly touched surfaces in your home, such as doorknobs, light switches, and countertops.

Follow all the preventive measures to reduce the risk of transmitting Covid-19 to others.

Treatment of Covid-19

Currently, there is no definitive cure for Covid-19 caused by the 2019 coronavirus. However, treatment strategies are tailored to manage symptoms and mitigate the impact of the virus on patients.

Mild cases: Mild cases typically require rest, adequate hydration, and over-the-counter medications to alleviate fever and pain.
Moderate cases: Patients with moderate symptoms may need oxygen support for respiratory function. Hospitalisation may also be required for close monitoring and additional medical care.
Severe cases: Severe Covid-19 cases may demand intensive care and advanced respiratory support, such as mechanical ventilation, to maintain vital functions.

Medications used in treatment

Treatment also includes medications such as antivirals to prevent the virus from spreading, steroids to reduce inflammation, and antibiotics to control bacterial infections. Blood plasma transfusion is another option that includes blood donated by people who have recovered from Covid-19, called convalescent plasma.

FDA-approved treatments

Remdesivir (Veklury): On October 22, 2020, the FDA approved its first Covid-19 treatment, the medication remdesivir (Veklury). It is available by prescription to treat Covid-19 in people ages 12 and older who’ve been hospitalised. It’s administered as an intravenous (IV) infusion.

Monoclonal Antibodies: The FDA granted emergency use authorizations (EUAs) for monoclonal antibody therapies in November 2020. These synthetic proteins are designed to mimic the immune system’s response, helping in the fight against the virus.

How to protect yourself from Covid-19 virus?

• Wash your hands more regularly, for at least 20 seconds, especially after being in public places or touching surfaces.
• If you cannot wash your hands with soap and water, then use hand sanitiser, containing at least 60 [percent alcohol.
• Avoid touching your face, especially your eyes, nose and mouth.
• Do not go out if you are feeling sick or experiencing cold or flu-like symptoms.
• Maintain a distance of at least 6 feet (2 meters) from others, avoid crowds, and minimize large gatherings.
• Wear your mask properly, everywhere that you need to. Make sure it covers your mouth and nose, and do not forget to put it in the wash regularly, too!
• Cover your nose and mouth with a tissue or your elbow when coughing or sneezing. Bin the tissue and wash your hands afterward.
• Try to avoid hand-to-hand contact with others, and maintain a safe distance from them.
• Steer clear of close contact with people who are ill, or if you feel poorly, talk to your doctor.
• Clean any objects you touch frequently.

Following these preventive measures consistently can significantly reduce the transmission of Covid-19 and protect you and those around you.

Vaccines

A Covid‑19 vaccine is a vaccine aimed at preventing infection and providing acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease (Covid-19). They have been deployed globally to immunise populations and achieve herd immunity.

In India, Covid-19 vaccination efforts have been extensive, aiming to curb transmission and severe illness caused by SARS-CoV-2. The country has primarily administered vaccines, including Covaxin and Covishield.

Covaxin

Covaxin, developed by Bharat Biotech in collaboration with the Indian Council of Medical Research (ICMR)-National Institute of Virology (NIV), is an inactivated virus vaccine approved in January 2022. It requires a two-dose regimen administered 28 days apart.

Covishield

Covishield, also approved in January 2022, is the Indian version of the Oxford-AstraZeneca vaccine, manufactured locally by the Serum Institute of India. It involves two doses of 0.5 mL each, with the second dose recommended between 4 and 6 weeks after the first dose.

Both vaccines aim to stimulate the immune system to recognise and combat the virus effectively.

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