Frequently asked questions (FAQs) 

A vaccine is a biological product that elicits an immune response against a specific bacteria or virus.

The immune response stimulates lymphocytes [white blood cells] in the body to produce antibodies and other inflammatory responses to kill off, inactivate or neutralise the germ when a person is exposed or infected.

The antibody response is generally specific to individual germs, hence the need for different types of vaccines.

Vaccines have been shown to be the most cost-effective health prevention strategy, second only to potable water, in preventing death.

Each year, it is estimated that immunization of children prevents at least 2.5 million deaths.

Immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine.

However, there still remain approximately 1.5 million deaths that could be prevented each year if vaccines were more accessible and widely used. 

Vaccines are ideally given to people before they are exposed to a specific virus or bacteria so that their immune system is able to mount an immediate defence against the targeted germ if they are inadvertently exposed or infected.

There are different approaches to developing vaccines, the ultimate aim of which is usually to elicit a functional immune response in order to prevent infection and disease:

• By using either a weakened or attenuated [reduced] version of the germ (e.g., oral polio virus, BCG – which is Bacillus Calmette-Guérin – measles, mumps and rubella viruses) that has limited ability to replicate or cause illness. Another approach is to use an inactivated version of the targeted vaccine (e.g., whole cell pertussis – which is whooping cough – vaccine).
• More common approaches to vaccine development include using only a specific target (antigen) of the germ, which is usually known to play a key role in the virulence of the germ. This antigen can also target the immune response to inactivate or neutralize the germ. These antigens are sometimes coupled with another chemical compound that is known as an adjuvant, which enables a more robust and long-lasting immune response.
• Newer technologies under investigation for vaccine development include presenting these antigens using a vector platform made from weakened viruses that cause mild or no illness in humans, and have been engineered to present the targeted antigen to the immune system. Several such vaccines are currently in clinical development for SARS-CoV-2 and other germs.
• Another new technology involves directly injecting the genetic material (messenger RNA or DNA) that codes for the antigen of interest. This genetic material is then incorporated into the host cellular machinery to produce the actual antigen (which would otherwise have been directly injected as a vaccine). Once produced, these antigens are still recognised by the immune system as ‘foreign’, which results in an immune response that produces antibodies and other immune responses that can inactivate the germ.

Vaccine development usually takes between 10-15 years from time of discovery to licensure. Vaccine development involves multiple experiments [phases] in animals before studies are start in humans, to mitigate safety issues, ensure the vaccine induces appropriate immune responses, and to evaluate whether the vaccine protects against infection or disease in animals before they advance to studies in humans.

In humans, the studies go through various stages of clinical development to ensure that vaccines are immunogenic [able to provoke an immune response in the body], safe, and are able to protect against infection or disease.

These initial studies start with investigations for safety, optimal dosage, and immune responses in a few hundred people (phase 1), before proceeding to larger phase 2 studies, which provide greater insight into safety, immune response, and whether the vaccine protects against disease. This often involves enrolling a few thousand volunteers. These are followed by phase 3 studies, which are much larger and involve ten-thousands participants to test how  safe and effective these vaccines are in protecting against disease, and particularly severe diseases.

The clinical development of new vaccines can range between US$5-million to US$1-billion (± R85 million to R170 billion). The cost of manufacturing vaccine varies from less than a dollar to more than US$100 (±R1700) per dose.

Some of these costs include efforts to recoup the cost of investing in the development of the vaccine rather than the actual cost-of-goods.

The cost also varies depending on the complexity of the manufacturing process involved, which differs for the various designs of vaccines.

Reasons put forward by people that are opposed to vaccines (sometimes known as ‘anti-vaxxers’) differ, but are often based on unsubstantiated concerns and rumour-mongering over the safety of vaccines, or that vaccines are a ploy by Big Industry to maximise profits.

Furthermore, the success of vaccines in improving health and reducing the burden of previous major causes of death (e.g., measles and whooping cough), often leads to unfounded complacency on the need for continual immunisation against these life-threatening germs.

Vaccines are among the most powerful tools to mitigate the consequences of life- threatening germs. This applies even more so to germs that infect the respiratory system, which are more efficiently spread between people.

In the absence of a vaccine against Covid-19, there is likely to be ongoing spread of the virus that will continue to cause severe illness and death, especially in those older than 65 years and adults with co-morbidities such as obesity, hypertension, and diabetes.

It is possible that, over time, when approximately two-thirds of the population have been infected by SARS-CoV-2, that Covid-19 will cause fewer deaths. However, this will depend on whether natural infection with the virus is able to induce a long-lasting and effective immune response.

An effective vaccine against Covid-19 can short-circuit the period over which at least two-thirds of the population become immune, which could assist in containing the risk of infection by the virus, even among those not vaccinated.

Furthermore, a Covid-19 vaccine will provide direct protection to vaccinated individuals against severe illness caused by SARS-CoV-2, including those individuals at high risk for severe disease.

In the absence of a Covid-19 vaccine, we will likely need to continue living the guarded lifestyle we are currently practising for at least two to three years, during which time we can anticipate multiple waves of Covid-19 outbreaks. 

As with most human vaccines, there were several animal species used in vaccine safety and efficacy trials, including ferrets, mice and Rhesus macaques.

Although the development of this vaccine is on accelerated timeline to address an unprecedented pandemic, the clinical development of the vaccine has built-in reviews processed by an independent international Data and Safety Monitoring Committee, as well regulatory oversight in South Africa by the South African Health Products Regulatory Authority (SAPHRA) and the University of the Witwatersrand Human Research Ethics Committee.

The vaccine will only be licensed for use after adequate studies have been undertaken to confirm its safety and effectiveness.