COVID-19 VACCINES

The fight against COVID-19 has seen vaccine development move at record speed. 

There are more vaccine candidates simultaneously in the pipeline for COVID-19 than ever before for an infectious disease. All of them are trying to achieve the same thing i.e. immunity to the virus, or to stop transmission. They do so by stimulating an immune response to an antigen, a molecule found on the virus.

In the case of COVID-19, the antigen is typically the characteristic spike protein found on the surface of the virus, which it normally uses to help it invade human cells.

THE BEST VACCINE:

The best COVID-19 vaccine is the first one that is available to you. All currently authorized and recommended COVID-19 vaccines: are safe, effective, and reduce your risk of severe illness.

THE FOUR MAIN TYPES OF COVID-19 VACCINES:

There are four categories of vaccines available: 

1. i) Whole virus Vaccine (inactivated viral Vaccine), ii) Protein subunit Vaccine, iii) Viral Vector Vaccine and iv) Nucleic Acid Vaccine (RNA AND DNA). Some of them try to smuggle the antigen into the body (whole virus Vaccine), others use the body’s own cells to make the viral antigen.

✓WHOLE VIRUS VACCINE:

Many conventional vaccines use whole viruses to trigger an immune response. There are two main sub-types.

1)Live attenuated vaccines: these use a weakened form of the virus that can still replicate without causing illness.

2)Inactivated vaccines: these use viruses whose genetic material has been destroyed by heat, chemicals or radiation so they cannot infect cells and replicate, but can still trigger immune response.

The advantage of inactivated viral Vaccine is, it is suitable for people with compromised immune systems and as there are no live components, so no risk of the vaccine triggering disease.

Inactivated Vaccine Examples: Sinovac, Sinopham,

✓VIRAL VECTOR VACCINES:

Viral vector-based vaccines don’t actually contain antigens, but rather use the body’s own cells to produce them. They do this by using a vector virus to deliver genetic code for antigen (spike proteins found on the virus surface) into human cells. By infecting cells and instructing them to make large amounts of antigen, which then trigger an immune response.

The viral vector acts as a delivery system, providing a means to invade the human cell and insert the code for antigens of a different virus (the virus you’re trying to vaccinate against). The vector virus itself is harmless, so the cells only produce antigens leading to an immune response, without developing disease.

Viral vector vaccine mimics what happens during natural infection with the virus. It has the advantage of triggering a strong cellular immune response.

Examples: Asta Zeneca, Sputnik Light, Sputnik V, Johnson & Johnson.

✓PROTIEN SUBUNIT VACCINES:

Protein subunit vaccines contain purified pieces of a virus, which have been specially selected for their ability to stimulate immune cells.

Subunit vaccines contain fragments of protein and/or polysaccharide from the virus, which have been carefully extracted to produce a strong and effective immune response. for restricting the immune system’s access to the pathogen, subunit vaccines are considered very safe and Suitable for people with compromised immune systems.

Examples: Novavax

✓ NUCLEIC ACID (mRNA) VACCINES:

Nucleic acid vaccines use genetic material from a disease-causing virus to trigger protective immunity against it.

Depending on the vaccine, the genetic material could be DNA or RNA; in both cases, it provides the instructions for making a specific protein from the virus, which the immune system will recognize as an antigen. Once inserted into host cells, this genetic material is read by the cell’s own protein-making machinery and used to manufacture antigens, which then trigger an immune response.

RNA vaccines encode the antigen of interest in messenger RNA (mRNA), Because of its transitory nature, there is zero risks of it integrating with human genetic material. The RNA can be injected by itself, encapsulated within nanoparticles.

Once the RNA is inside the cell, it starts producing antigens, these are then displayed on the cell surface, where they can be detected by the immune system, triggering a response.

As there are no live components, so no risk of the vaccine triggering the disease. Some RNA vaccines require ultra-cold storage.

Examples: Pfizer, Moderna

VACCINE SAFETY AND EFFICACY:

COVID-19 vaccines are not experimental. These were developed using science that has been around for decades. They went through all the required stages of clinical trials. Extensive testing and monitoring have shown that these vaccines are safe and effective.

They can keep you from getting and spreading the virus that causes COVID-19. Even if you get COVID-19, these vaccines help keep you from getting seriously ill. 

After you are fully vaccinated for COVID-19, you can resume many activities that you did before the pandemic. You can resume activities without wearing a mask or staying 6 feet apart. 

None of the COVID-19 vaccines contain the live virus that causes COVID-19 so a COVID-19 vaccine cannot make you sick with COVID-19.

COVID-19 is still a threat to people who are unvaccinated. Some people who get COVID-19 can become severely ill, which could result in hospitalization, and some people have ongoing health problems several weeks or even longer after getting infected. So get vaccinated regardless of whether you already had COVID-19. Studies have shown that vaccination provides a strong boost in protection in people who have recovered from COVID-19.

VACCINE SIDE EFFECTS:

COVID-19 vaccination will help protect you from getting COVID-19. You may have some mild side effects, which are normal signs that your body is  

building protection. These side effects may affect your ability to do daily activities, but they should go away in a few days. Most people have no side effects. 

∆Common side effects:

On the arm where you got the shot: 

• Pain • Redness • Swelling

Throughout the rest of your body: 

• Tiredness  • Headache • Muscle pain • Chills • Fever • Nausea

∆Rare side effects:

Some rare side effects also have been reported but the incidence ratio is very very low (about 0.0004%). These include

• mild to moderate myocarditis (specific to Pfizer and Moderna)
• rare blood clotting syndrome

(specific to Astra Zeneca and johnson & johnson in persons under 40 years of age)

VACCINE BOOSTER DOSE:

Vaccination with two doses helps prevent infection, and in those that do still get infected, lessens the impact of the virus by reducing disease severity, the transmission of infection, and death.

An Oxford-based study found that a third dose of the AstraZeneca vaccine induces a “strong” immune boost against Covid-19 and its different variants.

The administration of a third jab more than six months after the second shot raises the number of antibodies within the blood back to the same levels seen in the wake of double-dose vaccination.

Plans to give people a third shot have been unveiled by the UK’s Joint Committee on Vaccination and Immunisation (JCVI). The two main arguments to support giving a third dose are that the effectiveness of the first two jabs falls over time, and that there’s a need to take new vaccines to deal with viral variants, such as the delta variant.

Pfizer BioNTech also plans to ask U.S. and European regulators to authorize a booster dose of its COVID-19 vaccine, based on evidence of greater risk of infection six months after inoculation and the spread of the highly contagious Delta variant.

VACCINE COCKTAIL:

The Com-Cov study, led by Professor Matthew has demonstrated that people can safely receive a first shot of the AstraZeneca vaccine followed by a second dose of the Pfizer Vaccine over a four-week period (more potent) and vice versa (less potent).

Both of these mixed pairings also produced more antibodies than the standard two-dose AstraZeneca schedule.

this type of vaccination induces “high concentrations” of antibodies that target the spike protein which covers the outside of Sars-CoV-2.

Some participants who received two different doses over a 28-day period reported fever, chills, fatigue, headache, joint pain and muscle ache after their second dose. There was no hospitalization following the onset of these symptoms, which were short-lived, with the mixed dosing schedule ultimately found to be safe.