Covid-19 crisis: all you need to know about available vaccines.

The Covid-19 (SARS-CoV-2) crisis has created an unprecedented need for vaccines globally. As vaccines are being developed rapidly and approved without compromising clinical trial protocols, there are concerns of equitable distribution. Wealthy nations represent just 16% of the world’s population, but they have bought more than half of global SARS-CoV-2 vaccine doses. At the time of writing, more than 244 million people have taken the vaccination shots worldwide, most of them in wealthy nations, while more than 2 billion people in some 210 countries are yet to receive a single shot. Vaccines are essential public health tools. There is no doubt that these vaccines are safe, effective, and hold the key to mitigating the pandemic’s ravaging impact. Otherwise, why would there be a rush to hoard the vaccines? COVAX, a global alliance comprising 190 countries, including Ghana, was established to ensure safe, effective, and equitable distribution of vaccine doses. Therefore, Ghana set the pace to be the first recipient of the COVAX vaccine in an ambitious global vaccination drive. Already, there are good signs that the vaccines are working. For the past seven weeks, global cases of the pandemic have decreased consecutively, according to a monitory report from the World Health Organization (WHO). Analysts have attributed the decrease to the rapid roll-out of vaccines and the continuous strict observation of SARS-CoV-2 restriction protocols in many countries worldwide. But not sufficient data is available to support these claims amid the emergence of more contagious variants of the virus. In Africa, the virus’s new variants have taken an aggressive toll, pushing the total number of deaths to surpass 100 thousand. Therefore, rapid deployment and roll-out of vaccines are essential to stop the further spread of the new variants. As a country with already constraint healthcare systems, a prolonged burden of SARS-CoV-2 and its mutants could be catastrophic. It will only be prudent to deploy the available vaccines as urgently as possible. The longer the SARS-CoV-2 continues to infect and spread in the population, the more new and complex variants we must deal with. Widespread skepticism and vaccine hesitancy might undermine our national vaccination efforts. But collectively, we can prevail. Here, an attempt is made to provide some information on all that you need to know about some available vaccines to make an informed decision.

What does a vaccine do, and how is it made?

A vaccine trains the immune system to defend the body against disease. This is done by prompting the immune system to create protective proteins called antibodies. A vaccine does not cause disease or put you at risk of complications because it contains a killed or weakened form of the virus necessary to elicit the antibodies which fight against the real viral infection when exposed. Therefore, vaccination is a safe and effective way of protecting people against infectious diseases before they get infected. In general, vaccines are made based on three main approaches used to trigger the immune system to produce antibodies without causing disease. The whole-microbe approach uses the whole germ (virus or bacterium). But it is killed or inactivated using chemicals, heat, or radiation. The flu and polio vaccines, for example, use this approach. Under this approach, a live virus can also be weakened or attenuated to make the vaccine elicit an immune response in the body without causing disease. Examples of live-attenuated vaccines are measles, mumps, rubella (MMR), and chickenpox and shingle vaccines that are already familiar and used globally to control these diseases effectively. Also, a harmless virus (vector) can be used to deliver specific sub-parts or proteins of the germ to elicit an immune response in the body. The Ebola vaccine is an example of a viral vector vaccine. The subunit approach uses subunits or specific parts of the virus that the immune system needs to recognize to elicit an immune response. This type of vaccine does not use a whole virus or a harmless virus as a vector to trigger an immune response. Whooping cough, tetanus, diphtheria, and meningococcal vaccines are examples of subunit vaccines. Finally, the genetic approach is novel and uses a section of the genetic material (nucleic acid) that provides instructions for making specific proteins of the virus.

What is contained in a vaccine?

The ingredients in a vaccine each play an essential role in making the vaccine safe and efficacious. A vaccine normally contains the antigen, which is the killed, inactivated, or weakened form of the virus, which trains the body to recognize and fight diseases when exposed. A vaccine also contains an adjuvant (like aluminum phosphate, aluminium hydroxide, or potassium aluminium sulphate), which helps the vaccine work better by boosting the immune response. Preservative (2-phenoxyethanol) is also contained in a vaccine to ensure that it remains safe. Finally, the vaccine contains a stabilizer (lactose, sucrose, glycine, or yeast-derived albumen) which protects the vaccine during storage and transportation.

Which Covid-19 vaccines are available and approved?

The Oxford AstraZeneca and the Sputnik V vaccines utilize the viral vector approach design. They have been approved by the Food and Drug Authority (FDA). The Oxford AstraZeneca vaccine originated from Britain. Under the vaccine equity distribution scheme (COVAX Facility), this vaccine was made available to Ghana from the Serum Institute of India, a partner company. The Oxford AstraZeneca vaccine showed 62% efficacy in clinical trials. According to experts, any vaccine with an efficacy rate of over 50% could stop outbreaks. More importantly, this vaccine is proven to be safe and effective against SARs-CoV-2 symptomatic infection and could reduce hospitalization and death. Therefore, it is prudent to utilize the vaccine under the present public health circumstances. The WHO Strategic Advisory Group of Experts on Immunization (SAGE) has recommended using the Oxford AstraZeneca vaccine. In Europe, the European Medicines Agency (EMA) has approved AstraZeneca. More than 40 countries, including Britain, India, and Mexico, have already authorized the vaccine. But, in Denmark, Germany, and Lithuania, the vaccine will not be given to people older than 65 due to insufficient data documenting its benefits for that age group. The exclusion of this group was based on the precautionary principle and nothing to suggest that the AstraZeneca vaccine has bad effects on the elderly. Although in South Africa, vaccination with the AstraZeneca vaccine has been paused due to data suggesting its ineffectiveness against the virus’s new variants, the data remains scanty. The sputnik V vaccine (also known as Gam-COVID-Vac) is manufactured in the Russian state Institute, Gamaleya. Though initially met with criticisms of inappropriate haste, corner-cutting, and a lack of transparency in its development, a recent phase 3 clinical trial report showed the clear scientific principle of vaccination had been demonstrated. The Sputnik V vaccine was found to be 92% effective. But the results were demonstrated in white adults aged 18 years and older pending further trials in diverse participants. The vaccine was found to exhibit a strong protective effect against SARS- CoV-2 in all participant age groups. Though the Sputnik V vaccine is under review by SAGE, more than 20 countries, including Russia, Iran, Argentina, UAE, Palestine state, Hungary, Egypt, and Algeria, have authorized its use.

Other vaccines such as Johnson and Johnson vaccine (vector vaccine) has an efficacy of 66%, while the Pfizer- BioNTech and Moderna vaccines that use genetic approach designs have an efficacy of 95% and 94%, respectively. The oxford AstraZeneca, Sputnik V, and the Johnson and Johnson vaccines are more suitable and convenient for use in our context compared with the Pfizer-BioNTech and Moderna vaccines which are logistically handicapped in terms of storage and distribution. The Pfizer- BioNTech, Moderna, and AstraZeneca are the first three vaccines authorized and widely deployed in many countries including Britain, the European Union, and the United States.

Oxford-AstraZeneca and Sputnik V compared with other vaccines.

Vaccine/countryTypeDosesInterval between dosesEffectiveness (%)Age groupLong-term duration of protectionStorage
Oxford Uni-AstraZeneca/Britain, IndiaViral vector (genetically modified)x 28 to 12 weeks6218 years and aboveNo sufficient data availableRegular fridge temperature
Gamaleya (Sputnik V)/RussiaViral vectorx 221 days9218 years and aboveNo data sufficient data availableRegular fridge temperature
Moderna /USARNA (part of genetic code)x 228 days9418 years and aboveNo sufficient data available-20 oC up to 6 months
Pfizer-BioNTech/USA, GermanyRNAx 221 to 28days9516 years and aboveNo sufficient data available-70 oC
Johnson and Johnson/USAViral vectorx 1 6618 years and aboveNo sufficient data available2-8oC for three months or -20 oC for 2 years

Who should take a vaccine?

All the vaccines that have been proven safe and effective, including the Oxford-AstraZeneca and the Russian Sputnik V vaccines, did not recruit children below 18 years old, pregnant, and breastfeeding mothers in clinical trials. Therefore, limited data exist to document the safety and effectiveness of these vaccines among these population groups. This is the main reason why these groups are currently excluded from taking the available vaccines. But pregnant women may receive the vaccine if the benefit of vaccinating a pregnant woman outweighs the potential vaccine risks. However, the vaccination should be done in consultation with a healthcare provider.

Those who are 18 years and older can take the vaccine. Available SARS-CoV-2 data should be used to inform prioritized groupings for the vaccination. But since the vaccines are limited, it is recommended that healthcare workers who are at high risk of exposure and people above the age of 65 should be prioritized. Also, persons with comorbidities, including obesity, cardiovascular disease, respiratory disease, and diabetes, are at high risk of severe SARS-CoV-2 are recommended to take the vaccination shot. Furthermore, those who have had SARS-CoV-2 infection in the past should take the vaccination. But they can choose to take the shot after six months from the time of infection. This is because a person who has recovered from the infection has circulating antibodies in his/her body that offers a certain degree of protection for at least six months. Though there is insufficient data on people living with HIV or autoimmune conditions or who are immunosuppressed, individuals can take their vaccination shots in consultation with a healthcare provider if they have been prioritized or recommended to take the vaccination. Finally, people with a severe allergic reaction to any vaccine ingredient should avoid taking a shot.

 What are the Side effects after taken the vaccine?

Mild side effects are normal with any vaccine inoculation. The side effects signify that the vaccine is working and that your body’s immune system is reacting to the vaccine as it should. Most people will experience pain with redness and swelling at the injection site after taking the vaccination shot. Other common side effects include fatigue, headache, muscle and joint pain, chills, and a slight temperature rise. These side effects are well-known and transient, so you do not need to call your doctor if you experience such effects. However, it is recommended that those who experience a severe reaction after taking a vaccination shot should seek immediate medical attention and avoid the second dose later.

What is herd immunity?

Herd immunity is the point at which the population is resistant to the virus. When 70% or more of the population is vaccinated, it is possible to achieve herd immunity after some time when the virus cannot infect people and eventually vanquished from the population. However, this depends on the virus’s contagiousness, which is measured by the reproductive number, R. The R number is how many people each infected person will infect on average. Also, the efficacy of a vaccine is a key determinant of herd immunity. The higher the efficacy of a vaccine used in vaccination, the more likely the possibility of achieving herd immunity quickly within the threshold. A low efficacy vaccine would require that we vaccinate a wider population or entire population to achieve herd immunity- this is sometimes hard to achieve and not feasible. In comparison, the Sputnik V vaccine is more likely to facilitate herd immunity than the AstraZeneca vaccine due to its high efficacy. Therefore, strategically, the two vaccines may be used among the prioritized population groups to facilitate herd immunity. Since we have two shots or doses for each vaccine, it is important to ensure that the second dose comes from the same vaccine as the first dose.

How can we achieve herd immunity?

Herd immunity is important. It protects those unvaccinated, such as children, pregnant women, breastfeeding mothers, and the immunosuppressed. We can reach herd immunity either by waiting long enough so that large parts of the society pass through infection, by reducing the infection through observing SARS-CoV-2 restriction protocols forever, or by vaccinating enough people. But we cannot afford further spread of the virus or observe SARS-CoV-2 restrictions forever. That is why vaccination holds the key to getting our normal life back from the pandemic. The science behind herd immunity probably informed the government target of getting 20 million Ghanaians vaccinated. Collectively, we can support the national vaccination efforts towards achieving herd immunity by getting vaccinated and encouraging more people to get vaccinated. Though we cannot rely solely on vaccines, the availability of vaccines offers us the opportunity to take a step ahead of the virus while observing basic public health rules. Strategic communication for SARS-CoV-2 vaccination is crucial and should be a collective responsibility of healthcare professionals, policymakers, the media, chiefs, opinion leaders, and the public.


Johns Hopkins Bloomberg School of Public Health.

World Health Organization.

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