What is Covid-19?
SARS-CoV2 or Covid -19 is a virus of the coronavirus family. It is a type of RNA virus because it has RNA in its genetic material.
Most coronaviruses circulate among animals (pigs, camels, bats) but if these viruses are transmitted to humans, they can cause disease.
The SARS coronavirus or SARS-CoV was responsible for severe acute respiratory syndrome between 2002 and 2004.
The MERS coronavirus (MERS-CoV), identified in 2012 and transmitted from an animal reservoir in camels, is responsible for the Middle East respiratory syndrome (MERS).
The MERS coronavirus continues to cause sporadic and localized outbreaks.
SARS-CoV-2 or COVID-19 is a new (novel) coronavirus that has not been previously seen in humans and causes coronavirus (COVID-19) disease
COVID-19 virus uses proteins on its outer surface, called spike (S) proteins, to enter the body’s cells and cause COVID-19 disease.
This virus emerged from China in 2019 and is affecting humans until today.
Like other viruses, the COVID 19 virus underwent mutations and currently, several variants are circulating around the world.
The UK identified a variant named B.1.1.7 in 2020. This variant was first detected in the United States in late December 2020.
In California, United States, other variants called B.1.427 and B.1.429 were identified and detected in December 2020.
In South Africa emerged another variant called B.1.351. Cases caused by this variant were first reported in the United States in late January 2021.
In Brazil, a variant called P.1 emerged, which was first detected in the United States in late January 2021.
All the emerged variants appear to have increased transmissibility.
Brief Review of the Human Immune System
When a pathogen like the virus that causes COVID-19 invades our body, our white blood cells, which are the specific cells of our immune system, fight the infection.
There are different types of white blood cells, each with different functions. For example, T lymphocytes are a type of white blood cell that attack infected cells, while B lymphocytes are another type of white blood cell that attack the pathogen through the production of antibodies.
Natural Immune Response and Acquired Immune Response
The first time the human body is infected with a new pathogen, the body creates the necessary tools to fight the attack and overcome the infection. Faced with a future exposure, the immune system will have created a “natural immunity” and will respond by remembering what it learned about protecting the body against that pathogen.
Vaccines help our bodies develop immunity to a certain pathogen without us having to contract the disease. Vaccines cause the body to produce a supply of T cells and B cells capable of remembering how to fight that pathogen in the future.
The process of developing immunity through vaccination is called “acquired immunity”
An Overview of Types of Approved Emergency COVID 19 Vaccines around the World
Types of COVID-19 Vaccines–
mRNA vaccines – Genetically Engineered-
Vector vaccines – Genetically engineered -DNA technology –
Inactivated virus vaccines-Killed virus
Protein Base Recombinant vaccines– Genetically Engineered-
Brief Review of a Human Body’s Cell Mechanism
Human cells are made up of a nucleus and a cytoplasm. The nucleus contains DNA, a double-bond chain with genetic information. DNA is unwrapped, decoded and transported in single chains (RNA) through a messenger (mRNA) to the cytoplasm where the production of proteins is made by ribosomes in the cytoplasm.
The mRNA is the intermediate step between the translation of DNA that encodes protein and the replication of the protein in the cell cytoplasm.
Human body’s cells handle genetic information from DNA to RNA and the reverse process is not possible.
Differences between COVID 19 Vaccines Authorized for Emergency Use
mRNA Vaccines
How do they work?
They use strands of the Covid 19 genetic code capable of instructing our cells to reproduce the “S protein” that is found on the surface of the virus and causes COVID-19 disease. Our immune system recognizes the protein S as foreign and begins to develop an immune response producing antibodies, as in natural infection against COVID-19.
Pharmaceutical: Pfizer (United States based company)/BioNtech (Company based in Mainz, Germany)
Type of Vaccine: Messenger (mRNA) vaccine
Number of doses: 2 (separated by 21 days)
Efficacy: 95%
Store and transportation Requirements: -70C
Side Effects Reported: pain at the injection site, rash, headache, muscle soreness, nausea, fever, anaphylaxis, fatigue, chills, joint pain, swollen lymph nodes, and Bell’s Palsy (a sudden, and usually temporary, weakening or paralysis of the facial muscles)
Observations-This vaccine was authorized in US-December 11, 2020
As well as United States, the vaccine is being used in a number of other places including: Canada, United Kingdom, Belgium, Austria, Israel, Italy, Spain, Switzerland, France, Australia, Japan, Mexico, Colombia, and Chile
Pharmaceutical: Moderna (United States based company)
Type of Vaccine: Messenger (mRNA) vaccine
Number of doses: 2 separated by 28 days)
Efficacy: 95%
Store and transportation Requirements -20C
Side Effects Reported: pain at the injection site, rash, headache, vomiting, muscle soreness, nausea, fever, fatigue, joint pain, chills, Bell’s Palsy, allergic reactions, anaphylaxis, swollen lymph nodes.
Observations-This vaccine was authorized in US-December 18,2020
As well as United States, the vaccine is being used in a number of other places including: Canada, Austria, Italy, Belgium, France, Spain, Switzerland, and Israel
Viral Vector vaccines
How do they work?
These vaccines are made up of other modified viruses that belong to the adenovirus family (DNA viruses) that causes the common cold
These modified adenoviruses (which cannot reproduce in the body or cause disease) carry the gene that makes the SARS-CoV-2 protein S.
The immune system will recognize this protein S as foreign and will produce natural defenses (antibodies and T cells) against that protein
Ebola’s vaccine is another example of a viral vector vaccine
Pharmaceutical: – Janssen – Johnson & Johnson (United States based company)
Type of Vaccine: Viral Vector (Non-replicating Ad26 viral vector)
Number of doses: 1
Efficacy: 85%?
Store and transportation: Regular fridge temperature (2-8C)
Side Effects Reported: pain, redness and swelling in the injection’s site, throat pain, nausea, rash, allergy, headache, muscle soreness, pain in the arms, legs and backache, joint pain sweating, tremor, chills and fever.
Observations–
The vaccine was developed at Harvard University and in Leiden, Netherlands and authorized in US-February 27,2021
As well as United States, the vaccine is being used in South Africa
Pharmaceutical: Oxford/Astra Zeneca (AZD1222)
Type of Vaccine: Viral Vector (Non-replicating chimp adenoviral vector)
Number of doses: 2 (28 days apart)
Efficacy: 82%?
Store and transportation Requirements Regular fridge temperature (2-8 C)
Side Effects Reported: pain in the site of the injection, nausea, vomiting, diarrhea, loss of appetite, abdominal pain, fatigue, rash, headache, muscle soreness, fever, chills, transverse myelitis? (inflammation of the spinal cord), temporary neutropenia? and blood clots?
Observations–The vaccine has been approved for use over 20 countries including the United Kingdom, Argentina, India, Mexico, France, Belgium, Italy, Austria, Brazil, El Salvador, and Spain
In the United States it has not yet been approved. The safety of the vaccine is being reviewed after some people develop unusual blood clots.
AstraZeneca-Oxford will apply for FDA clearance in the first half of April
Pharmaceutical: -Gamaleya- Sputnik V (Russia)
Type: Viral Vector
Number of doses: 2
Efficacy: around 92%?
Store and transportation Requirements: Regular fridge temperature (2-8C)
Side effects Reported: flu-like symptoms, heart palpitations, pain at the injection site and fatigue.
Observations-As well as Russia, the vaccine is being used in a number of other places including: Argentina, Mexico, Venezuela and Iran
The United State (US) applicant is R-Pharm Germany GmbH. The European Medicines Agency (EMA) will assess the vaccine’s compliance with the US standard for use and approval.
Inactivated (killed) virus
How do they work?
These vaccines work by using dead viral particles to expose the body’s immune system to the virus without risk of a severe response.
They are a more traditional method of vaccine that is used with success in many known vaccines, such as rabies, Hepatitis B, Hib, Polio, and Tetanus
Pharmaceutical: Sinovac “Corona Vac”- vaccine
Type of Vaccine: Inactivated virus
Number of doses 2
Efficacy: 83.5%
Store and transportation Requirements Regular fridge temperature (2-8C)
Side Effects Reported: pain in the injection site, rash, headaches, muscle pain, fever, nauseas and vomiting
Observation-The vaccine is being used in China and in a number of other places including: Turkey, Brazil, Chile Colombia, and Uruguay
Pharmaceutical: Sinopharm
Type of Vaccine: Inactivated virus
Number of doses 2
Efficacy: 86%
Store and transportation Requirements Regular fridge temperature (2-8C)
Side Effects Reported: injection site pain, rash, headaches, muscle pain, fever, nauseas and vomiting
Observation– the vaccine is being used in China and in a number of other places including: United Arab Emirates, Peru, Morocco, and Argentina
Pharmaceutical: Covaxin
Type of Vaccine: Inactivated virus
Number of doses 2
Efficacy: 90%?
Store and transportation Requirements Regular fridge temperature (2-8C)
Side Effects Reported: pain in the injection site, headache, fatigue, fever, body ache, abdominal pain, nausea and vomiting, dizziness-giddiness, tremor, sweating, cold, cough and injection site swelling.
Observation-The vaccine is being used in India
Vaccines In phase of testing (Clinic Trial)-
Novavax (United States based company)
Type of Vaccine: Protein-based recombinant nanoparticle with an adjuvant
It’s a protein subunit vaccine, which means that it uses a lab-made version of the SARS-CoV-2 spike protein.
Number of Doses: 2 (21 days apart)
Observation: Candidate vaccine in the United States and United Kingdom
As of February 2021, clinical trials for this vaccine are underway in the US
Novavax was the first vaccine to demonstrate clinical efficacy against UK and South African variants
Novavax will release the results of its trials and will apply for FDA clearance in April or early May.
Pharmaceutical: Sanofi / GSK (GlaxoSmithKline)
Type of vaccine: Protein- based recombinant
Sanofi / GSK is a vaccine that uses pieces of the novel coronavirus in combination with the baculovirus (virus, commonly found in moths)
Observation: Issued by United Kingdom and France
Pharmaceutical: Cure Vac
Type of Vaccine: Messenger (mRNA) vaccine
Observation-As well as Germany, the vaccine has different study centers located on Belgium, Netherlands, Spain, Mexico, Colombia, Argentina and Dominican Republic
Pharmaceutical: IDT Biologika
Type of Vaccine: Viral Vector
Observation– Is being develop in Germany
Epivac Corona Vaccine
It is an antigens-based vaccine that provokes an immune reaction against COVID-19 and promotes the further development of immunity.
Observation- Is being develop in Russia
CanSinoBio (China)
Type of Vaccine: Viral Vector
Observation: The CanSinoBIO vaccine is being tested in Pakistan, Mexico, Russia, Argentina and Chile
Frequent questions (FQ)
How long does natural immunity against Covid 19 last after having the disease?
It is not yet known with certainty but it is estimated that approximately 3 months to 11 months
How long does acquired immunity last after completing the vaccination schedule?
It is not clear how long the vaccine continues to protect.
The COVID-19 vaccine from Pfizer (PFE) and BioNTech (BNTX) for example, has been shown to be effective six months after the second dose, according to an ongoing analysis of phase 3 trial participants.
Can I get COVID after getting vaccinated?
Yes. The vaccine prevents more serious diseases if you do get the disease, but no vaccine is 100% effective. The vaccine also does not prevent the transmission of the disease to other people.
Should I isolate myself after receiving the vaccine? No.
Should I get vaccinated even after I have had the disease?
CDC recommends that people who have had the virus can benefit from getting the vaccine but “People with COVID-19 who have symptoms should wait to be vaccinated until they have recovered from their illness and have met the criteria for discontinuing isolation; those without symptoms should also wait until they meet the criteria before getting vaccinated” Also, people treated for COVID-19 with monoclonal antibodies or convalescent plasma, should wait 90 days before getting a COVID-19 vaccine”.
Do the COVID-19 Vaccines Protect Against New Variants of the Virus?
It is being investigated whether the antibodies generated through vaccination confer protection against the variants.
According to the CDC, the first data shows that vaccines can work against some variants, but could be less effective against others but more studies are needed
The researchers say the Pfizer vaccine, for example, produces an immune response that is likely to protect against the Brazilian variant of Covid-19
For its part, Moderna has started a new trial to test a vaccine specifically targeting the B.1.351 variant.
What types of antibody tests are there to detect protection against SARS-Cov2 / COVID-19?
There are 2 types of COVID-19 antibody tests to evaluate immunity (IgM / IgG). One test that evaluates the viral protein S (spike) and another test that evaluates the viral nucleocapsid protein
A positive test for nucleocapsid protein (IgM / Ig G) indicates PREVIOUS infection
A positive test for Spike protein (IgM / Ig G) indicates PREVIOUS infection or vaccination
Archive: April 04,2021
Author: Nancy Dutto, MD