Definition of a Vaccine

A vaccine is a type of medication that is used to prevent the spread of virus or bacteria among individuals. The COVID-19 vaccine is a viral vaccine that was created for the purpose of protecting the body against the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus causing the COVID-19 virus. These vaccines are perhaps the best hope in helping the global economy eradicate the pandemic totally. While testing the vaccines, in its Phase III trials, various COVID-19 vaccines demonstrated high efficacy between 70% - 90% in preventing symptomatic COVID-19 symptoms.

Vaccination of individuals, starting from the most vulnerable ones which include: persons above the age of 65 years; people with severe medical conditions irrespective of their age (except for children); and the frontline essential workers e.g., nurses, doctors and social workers, have started across the globe. Over 2 billion one hundred and twenty million (2.12 billion) doses of COVID-19 vaccines have been administered globally, and with 458 million people already fully vaccinated as at June 9, 2021.

Types of COVID-19 Vaccines

There are currently three groups of vaccines in which the COVID-19 vaccines have been modeled around: (1) Nucleic Acid; (2) viral vector vaccines and (3) killed whole virus according to the World Health Organization and GAVI (the vaccine alliance).

• Nucleic Acid Vaccines

There are currently two RNA Vaccines that has been approved by the WHO for usage i.e., the Pfizer-BioNTech vaccine and Moderna vaccine. These are messenger RNA vaccines. There are no DNA vaccines.

Nucleic acid vaccines use genetic material – either RNA or DNA – to provide cells with the instructions to make the antigen. In the case of COVID-19, this is usually the viral spike protein. Once this genetic material gets into human cells, it uses our cells' protein factories to make the antigen that will trigger an immune response.

• Viral Vector Vaccines

According to the Center for Disease Control and Prevention (CDC), the viral vector vaccines are made up of genetic material from the COVID-19 virus (specifically the spike protein antigen) which is inserted into a different kind of weakened live virus (an adenovirus). When the weakened virus (viral vector) gets into the human cells in immunized individuals, it delivers genetic material (spike protein antigen) to the human cells in their body. Once these cells display the spike proteins on their surfaces, the immune system responds by creating antibodies and defensive white blood cells against the spike proteins, which is similar to COVID-19 spike proteins. If individuals become infected with the COVID-19 virus, the antibodies will fight the virus by attacking its spike proteins, thereby preventing the virus from entering the human cells of the individuals. There are two viral vector vaccines that have been approved by the World Health Organization: Janssen/Johnson & Johnson Vaccine; and the Oxford/AstraZeneca vaccine. The Sputnik vaccine is a viral vector vaccine but has only been approved in Russia where it was created but not yet adopted by the World Health Organization. China is also making its own vaccine but not yet widely approved.

• Whole Virus Vaccines

Many conventional vaccines use whole viruses to trigger an immune response. There are two main approaches. Live attenuated vaccines use a weakened form of the virus that can still replicate without causing illness. Inactivated vaccines use viruses whose genetic material has been destroyed so they cannot replicate, but can still trigger an immune response. Both types use well-established technology and pathways for regulatory approval, but live attenuated ones may risk causing disease in people with weak immune systems and often require careful cold storage, making their use more challenging in low-resource countries. Inactivated virus vaccines can be given to people with compromised immune systems but might also need cold storage. Inactivated vaccines are now available for COVID-19 and probably not necessary. The vaccine is made by the Beijing based biopharmaceutical company Sinovac. It is an inactivated virus vaccine called CoronaVac. It works by using killed viral particles to expose the body’s immune system to the virus without risking a serious disease response. It is a more traditional method of vaccines. The corona viruses were inactivated by dousing them with a chemical called beta-propiolactone, which disabled the viruses by bonding to their genes so that they could no longer replicate. CoronaVac received emergency utilization approval from WHO on May 7^th, 2021.

• Protein Subunit Vaccines

Subunit vaccines use pieces of the pathogen - often fragments of protein - to trigger an immune response. Doing so minimizes the risk of side effects, but it also means the immune response may be weaker. This is why they often require adjuvants, to help boost the immune response. An example of an existing subunit vaccine is the hepatitis B vaccine. COVID-19 AstraZeneca and Johnson/Johnson vaccines are not protein subunits but viral vector vaccines. There are no plans to develop protein subunit vaccines for COVID-19.

Frequently Asked Questions Regarding The COVID-19 Vaccine

Although the COVID-19 vaccines shot has been taken by some citizens in countries all over the world (including Nigeria who received nearly 4 million vaccines (for 2 million people) on the 2^nd of March, 2021, yet some individuals still question its potential to help solve the current pandemic, thus various questions being asked.

Some of these questions include:

• Is the vaccine safe? COVID-19 vaccines are quite safe and effective; having been evaluated in Phase 3 trial in thousands of individuals and finding no underlying severe side effects, that warrants making the vaccine to be declared unsafe.
• What are the benefits of getting vaccinated? The COVID-19 vaccines might help prevent individuals from getting seriously ill from the COVID-19 virus or dying from COVID-19 caused by the virus.
• What vaccines are recommended for use? Currently, several COVID-19 vaccines are in clinical trials. However, vaccines such as the Pfizer-BioNTech COVID-19 vaccine; Moderna COVID-19 vaccine; Janssen/Johnson & Johnson COVID-19 vaccine; Oxford-AstraZeneca COVID-19 vaccines and recently CoronaVac by Sinophoric vaccines have all been approved for use by the World Health Organization (WHO).
• Can COVID-19 vaccine give you COVID-19? No. The COVID-19 vaccines can’t give you COVID-19 virus. The vaccines do not contain live attenuated COVID-19 virus, but antigen to spike proteins or killed/inactivated coronavirus.
• What are the possible side effect of a covid-19 vaccine? COVID-19 vaccine can cause mild side effects after the first or second dose which can include: pain, redness or swelling at the point where the shot was given; fever; fatigue; headache; muscle pains; chills; joint pain; nausea and vomiting; and swollen lymph nodes. There is a recommendation that all persons vaccinated be monitored for 15 minutes after their vaccination, so as to see any immediate reaction that might occur. Most side effects happen within the first three days after vaccination and typically last only one or two days. Blood clots in the brain which have been observed in AstraZeneca and Johnson/Johnson vaccine are very rare, occurring in 1 in 100,000 young women below 30 years, 1 in 250,000 of older women and 1 in 500,000 of others. It is an idiosyncratic (immunologic) side effects and can be effectively treated.
• How are these side effects being tracked in Nigeria? There are two bodies tracking adverse events following AstraZeneca COVID-19 vaccine: The Pharmacovigilance unit of NAFDAC and a special expert committee on adverse events following immunization set up by WHO in collaboration with the Federal Ministry of Health. All adverse events no matter how minor, are reported to NAFDAC who records them. Serious side effects requiring hospitalization or causing disability are referred to the WHO expert committee to evaluate and carefully analyze. A report is generated which is transmitted to WHO and the Ministry of Health for necessary action.
• Can I be vaccinated if I have underlying medical conditions? Yes, if an individual has any form of underlying medical conditions, he/she can get the vaccine – as long as he/she doesn’t have an allergic reaction to COVID-19 vaccines ingredients. However, if an individual has febrile illness, he/she should postpone vaccination till he/she has recovered.
• Can I stop following the preventive measures after vaccination? It is recommended that individuals who are fully vaccinated can visit other fully vaccinated people indoors with or without their masks or avoiding close contact. However, vaccinated persons should continue to take safety preventive measures such as wearing face mask; avoiding close contact with others when they are in public spaces; avoiding people who are at high risk of COVID-19; or people who are not yet vaccinated.
• Does COVID-19 vaccines give long – term protection? Due to the fact that these COVID-19 vaccines were recently developed, it can’t be ascertained how long they can protect the human body. However, according to data gathered by The World Health Organization, most individuals that recover from COVID-19 infection develop a better immune system that protects against reinfection (though the longevity of this protection can’t be determined at the moment).
• Which other vaccines can protect one against covid-19? Individuals’ needs to understand that except for vaccines created to protect the immune system against SARS-CoV-2, there are no other vaccines out there that can protect the body against COVID-19 virus. However, there are ongoing researches on whether other vaccines such as the Bacille Calmette-Guérin (BCG) vaccine, which is used to prevent tuberculosis – are also effective for COVID-19.
• Can one take other medicines before taking the vaccines? There isn’t any form of recommendation that an individual can take any pill/medicine that can relieve pain or possible discomfort that might arise side effects to the vaccines before taking the vaccines. However, medication can be gotten after the COVID-19 vaccine, for pain or other side effects if there are no medical reasons one shouldn’t take such medication.
• Is the vaccine safe for pregnant women / nursing mothers? Presently, there are no safety / preventive measures in COVID-19 vaccines for pregnant or breastfeeding women, but if there is any reason for such people to get vaccinated, it is advised that such group of women seek medical advice before such decision is taken. Pfizer vaccine is currently being tested in pregnant women and result will soon be available.
• Who shouldn’t get the vaccine? As at this moment, there have been no restrictions on people who should get vaccinated; however, children under the age of 16 are advised not to take the vaccines due to the side effects it may have in their body system, although after research and clinical trials Pfizer vaccine can now be given to children between the ages of 12 – 18 years.
• Who are those that needs the covid-19 vaccines the most? The COVID-19 vaccines are quite essential for every individual with no exception, but it has been recommended that certain personnel should be prioritized in the distribution of the vaccines; and they include: Health care personnel; people aged 65 and above; people aged between 16 and 64 with underlying medical conditions such as diabetes mellitus etc.; frontline essential workers such as teachers; other essential workers such as people who work in construction, food service companies, and Journalists.

[Next Article: Myths, Conspiracy Theories and Misinformation About COVID-19 Vaccine]

© Medical Tutors Limited