AN INTRODUCTION TO CORONA VIRUS AND ITS TREATMENTS


ORIGIN

Corona virus is a family of viruses that cause an infection in our nose, sinuses, or upper throat. Most of them are not dangerous. The term corona virus originated from the Latin term corona which means ‘crown’ due to the presence of crown-like spikes on its surface. The first signs and symptoms of respiratory tract infection were observed in 1962 in China.

COVID-19

The acronym COVID-19 is “CO” stands for Corona, “VI” stands for Virus, “D” stand for Disease and 19 stands for 2019. COVID-19 is a highly contagious disease caused by a new strain of corona virus, i.e. SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronovirus-2) that can cause respiratory tract infection. It can either affect your upper respiratory tract that includes sinuses, nose, and throat or lower respiratory tract including windpipe and lungs. More than 1 million people have died of COVID-19 across the world so far.

STRUCTURE AND GENOME OF CORONA VIRUSES

Corona virus is spherical enveloped virus which contains a single strand of positive-sense RNA similar to that of the host mRNA of approximately 26 to 32 kb. The distinguishing features are club-shaped projections from the viral envelope made of a highly glycosylated protein named spike protein which resembles a crown. The other three structural proteins are the envelope, membrane, and nucleocapsid proteins.

HOW IT SPREADS

This disease is highly contagious and is known to affect all age groups. People of higher age groups and those with pre-existing medical conditions such as high blood pressure, heart disease, lung disease, cancer or diabetes are at a high risk to develop severe symptoms.

When a person suffering with COVID-19 sneezes or coughs, the virus spreads to the surroundings via tiny droplets. These suspended viruses come into contact with the healthy person and get him/her infected. The chances are high if the person is within a distance of less than 1 metre from the infected person. However, the infection is generally mild in children due to their good immune system.

SYMPTOMS

The severity of COVID-19 symptoms can vary from mild to severe. Some people may have no symptoms at all. Common symptoms include fever, sore throat, cough and shortness of breath.

Other symptoms are:

  • Shortness of breath or difficulty in breathing
  • Muscle aches
  • Chills
  • Sore throat
  • Runny nose
  • Headache
  • Chest pain
  • Pink eye (conjunctivitis)

Some people with positive results had less common symptoms such as rash, nausea, vomiting and diarrhoea.

TESTS TO DETECT COVID

Following are the diagnostic tests accepted worldwide to detect COVID-19 virus:

RT-PCR tests

RT-PCR stands for “Reverse Transcription Polymerase Chain Reaction”. This test determines if a person has an active SARS-CoV-2 corona virus infection. This is done by checking a sample of nasal secretion collected using a nasopharyngeal swab for the genetic material of the virus. The RT-PCR test is widely regarded as the gold standard for COVID-19 testing. The duration of getting an RT-PCR report is within 24 hours.

Antigen tests

Antigen tests detect specific proteins (antigens) of the corona virus. This test also requires nasopharyngeal secretions for antigen testing, and positive results indicate infection. This test can generate results in just 15 minutes. However, there are higher chances of missing an active infection.

Antibody tests

The human immune system produces antibodies to curb bacteria, viruses, and other potential microbial threats. It takes few days for the immune system to produce these antibodies after being infected by the microbe.  Each type of microbe results in creation of correspondingly unique antibody which is beneficial for testing COVID-19 detection. The COVID-19 antibody test is done by a blood sample to detect antibodies that are corresponding to SARS-CoV-2.

Antibodies themselves can survive in the bloodstream several weeks post recovery, which implies that antibody tests are not reliable for detecting an active corona virus infection. However, they are useful as a way to test for past infection.

TREATMENT AND PREVENTIVE MEASURES

Presently, there is no defined treatment for Corona virus infection. However, patients are being given symptomatic treatments. Being a viral infection, more than 80% of the cases recover within few days. Few patients showing severe symptoms may be required to be admitted in hospitals and are kept under isolation so that others may not contract the virus.

You can reduce the spread of COVID-19 virus by taking simple preventive measures:

  • Wear a mask when you are going out from home.
  • Wash your hands with soap and water frequently or use an alcohol-based hand sanitiser.
  • Maintain at least one metre or three feet distance between yourself and anyone who is coughing or sneezing.
  • Avoid touching eyes, nose and mouth without washing your hands.
  • Cover your mouth and nose with your bent elbow or tissue while coughing or sneezing and dispose of the used tissue immediately.
  • If you think a surface may be infected, clean it with simple disinfectant to kill the virus and protect yourself and others.
  • If you have a fever, cough and difficulty in breathing, stay at home and seek medical attention.

When to undergo self-isolation

Self-isolation refers to staying indoors preferably in your own room without even coming in contact with other family members. If you got yourself tested for COVID-19 then you must self-isolate yourself till the reports are out. Also seek doctor’s advice in case the report is positive.

VACCINES FOR COVID-19

Worldwide efforts to produce a safe and effective COVID-19 vaccine so as to get life back to normalcy are bearing fruit.

There are three main approaches for designing a vaccine. Their differences lie in whether they use a whole virus or bacterium, just the parts of the germ that triggers the immune system or just the genetic material that provides the instructions for making specific proteins and not the whole virus.

The whole-microbe approach

Inactivated vaccine

The first way to make a vaccine is to take the disease-carrying virus or bacterium, or one very similar to it, and inactivate or kill it using chemicals, heat or radiation. This approach is used to make flu and polio vaccines.

Live-attenuated vaccine

A live-attenuated vaccine uses a living but weakened version of the virus or one that’s very similar. For example, MMR and chickenpox vaccines are live-attenuated vaccines. However, vaccines like this may not be suitable for people with compromised immune systems.

Viral vector vaccine

This type of vaccine uses a safe virus to deliver specific sub-parts called proteins—of the germ of interest so that it can trigger an immune response without causing disease. The Ebola vaccine is a viral vector vaccine and this type can be developed rapidly.

The subunit approach

A subunit vaccine is one that only uses the very specific parts (the subunits) of a virus or bacterium that the immune system needs to recognize. Most of the vaccines on the childhood schedule are subunit vaccines, such as whooping cough, tetanus, diphtheria and meningococcal meningitis.

The genetic approach (nucleic acid vaccine)

A genetic or nucleic acid approach is a new way of developing vaccines. It just uses a section of genetic material that provides the instructions for specific proteins, not the whole microbe. DNA and RNA are the instructions our cells use to make proteins. In our cells, DNA is first turned into messenger RNA, which is then used as the blueprint to make specific proteins.

First Vaccine for Covid-19        

Sputnik V is the world’s first registered vaccine based on a well-studied human adenoviral vector-based platform. It was developed by Russia’s Gamaleya Research Institute. It has shown an efficacy of over 90%.

Indigenous vaccines for Covid-19

Covishield

Covishield or Recombinant Chimpanzee Adenovirus vector vaccine is developed by encoding the SARS-CoV-2 Spike (S) glycoprotein with technology transfer from AstraZeneca/Oxford University. It is developed by Serum Institute of India, Pune and shows the efficacy of more than 70%. Covishield has been granted permission by Central Drugs Standard Control Organisation (CDSCO) for restricted use in emergency situation.

Covaxin

COVAXIN is developed using Whole-Virion Inactivated Vero Cell derived platform technology. Inactivated vaccines do not replicate and are therefore unlikely to revert and cause pathological effects. It is developed by Bharat Biotech that was developed in collaboration with the Indian Council of Medical Research (ICMR)—National Institute of Virology (NIV). Covaxin has also been granted permission by CDSCO for restricted use in emergency situation. However, the emergency use authorization for Covaxin is different from thet for covishield because the use of the former will be in clinical trial mode and all recipients would be tracked and monitored as if they are in trial.

nCov-Vaccine

Novel Corona Virus-2019-nCov-Vaccine is developed using DNA platform technology. It is developed by Cadila Healthcare Ltd. and is under Phase III clinical trial by the permission of Central Drugs Standard Control Organisation (CDSCO).

Other key players authorised around the globe are as follows:

Name Vaccine Type Primary Developers Country of Origin
Comirnaty (BNT162b2) mRNA-based vaccine Pfizer, BioNTech; Fosun Pharma Multinational
Moderna COVID‑19 Vaccine (mRNA-1273) mRNA-based vaccine Moderna, BARDA, NIAID USA
CoronaVac Inactivated vaccine (formalin with alum adjuvant) Sinovac China
AstraZeneca COVID-19 Vaccine (AZD1222); also known as Covishield Adenovirus vaccine BARDA, OWS UK
No name announced Inactivated vaccine Wuhan Institute of Biological Products; China National Pharmaceutical Group (Sinopharm) China
Sputnik V Non-replicating viral vector Gamaleya Research Institute, Acellena Contract Drug Research and Development Russia
BBIBP-CorV Inactivated vaccine Beijing Institute of Biological Products; China National Pharmaceutical Group (Sinopharm) China
EpiVacCorona Peptide vaccine Federal Budgetary Research Institution State Research Center of Virology and Biotechnology Russia
Covaxin Inactivated vaccine Bharat Biotech, ICMR India

Courtesy: https://www.raps.org/news-and-articles/news-articles/2020/3/covid-19-vaccine-tracker

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