When will we have a vaccine for Covid-19?
What is a vaccine?
Oxford Vaccine Group, a research group at the University of Oxford, defines a vaccine as a type of medicine that trains the immune system to remember the virus, stimulating the body’s immune response when it enters. Vaccines are designed to prevent disease, rather than treat a disease once you have caught it.
How do scientists develop a vaccine?
According to the US Department of Health and Human Services, vaccines can be classified into various types:
- Live attenuated vaccines: use a weakened (or attenuated) form of the germ, creating a strong and long-lasting immune response. It is known that one or two doses of this type of vaccine can provide people with lifetime protection.
- Inactivated vaccines: use a dead dosage of the germ. The inactivated vaccines are not as potent as live attenuated vaccines, requiring two to three doses over time called “booster shots” to increase ongoing immunity.
- Subunit, recombinant, polysaccharide, and conjugate vaccines: use specific pieces of the germ, such as proteins, sugars, or the capsid – which is a casing around the germ. This type of vaccine can be provided to almost everyone. Multiple shots over time for ongoing protection is required, however.
- Toxoid vaccines: Scientists target the parts of the germ that cause a disease (the toxin) instead of the germ itself, meaning that people still have the germ, yet it will not cause illness. Similar to some other types of vaccines, people may need booster shots to ensure ongoing protection.
How do we know if a vaccine is successful?
Vaccines cannot be made available within one or two months, it takes months to test, trial and ensure it is safe for humans. According to the World Journal Microbiology and Biotechnology, a vaccine should include two important aspects:
- The vaccine should be safe, even in immunocompromised people.
- The vaccine should be highly effective and optimally induce ‘sterilizing’ immunity.
The study also indicated that many vaccines used in response to epidemics and pandemics should include properties such as:
- Affordable cost: World Health Organization (WHO) Expanded Programme for Immunization limits the cost of a vaccine to no more than 50 cents-a-dose.
- High thermal stability, particularly in tropical countries.
- Multivalent single vaccine to protect against several regionally important infectious diseases.
- Long-lived immunity: some attenuated live viral vaccines give long-lived immunity after just one or two doses.
What is the current Covid-19 vaccine development stage?
Scientists worldwide are racing to develop a potent vaccine for Covid-19, bringing back normality to people’s lives. Presently, approximately two dozen coronavirus vaccines are in clinical trials, while another 140 are in the early development stage.
BBC News, reported on July 16 that studies in the US and UK indicated that scientists see a good immune response in volunteers, without serious side-effects.
Pharmaceutical company Pfizer and biotech company Moderna have said that early results from the two trials indicated promising results.
A recent study published on July 20 on the safety and immunogenicity of the Covid-19 vaccine by the University of Oxford said that the vaccine is safe, tolerated and immunogenic, with only mild and moderate side effects that can be treated with paracetamol. However, the university said that it plans to conduct further human trials in a diverse population, to ensure efficacy and safely.
Sarah Gilbert, a professor of vaccinology at the University of Oxford and who was part of the research team on the trials, said that “There is still much work to be done before we can confirm if our vaccine will help manage the Covid-19 pandemic, but these early results hold promise.”
However, a rollout of an effective vaccine may still take some time to be made publicly available. But it is hoped that it will be sooner, rather than later and that people at higher risk to the virus will be given priority to the vaccine.
This post is also available in: KH