The Current State of Vaccines (including COVID-19)
What vaccines are in development for COVID-19, and how effective are vaccines for other viruses?
COVID-19 has rapidly infected the world, infecting millions of people and destroying several economies. Scientists across the globe have been given a difficult task, creating an effective vaccine, but this is not easy. Usually, developing a truly effective vaccine requires years of research and testing, but this pandemic has forced researchers to condense this process into a couple of months. Let’s take a closer look at this process and the current state of vaccines for viruses, from COVID-19 to influenza.
What is a Vaccine?
In simple terms, a vaccine is something that introduces part of a virus, or antigen, to your body so that it can recognize that same virus in the future if you are ever infected and protect you from it.
When an antigen carried in a vaccine enters your body, it is noticed by antigen-presenting cells, which eventually leads to the ignition of an immune response. In the immune response, helper T-cells activate two types of white blood cells, or leukocytes: B-cells and cytotoxic T-cells. B-cells create proteins called antibodies, which bind to viruses and kill/disable them. Cytotoxic T-cells, like antibodies, also destroy viruses. When a vaccine is given, no real virus is introduced, so antibodies and cytotoxic T-cells are generated but not immediately used. Instead, they make sure you can quickly fend off a virus if it ever enters your body. This entire process is called active immunity.
The antigen introduced to the body is what separates the different categories of vaccines; the most prevalent types are:
- Virus vaccines: vaccines that inject inactivated or weakened versions of a virus to generate an immune response
- Viral-vector vaccines: vaccines that use a viral vector (disabled virus) to create viral proteins that trigger an immune response
- Protein-based vaccines: vaccines that inject proteins from a virus but no genetic material into the body to generate an immune response
- Nucleic-acid vaccines: vaccines that inject only the genetic material from a virus (single or double-stranded RNA or DNA)
Of these four types, the most effective types are protein-based and nucleic-acid vaccines because they are more specific and can be used on people with weaker immune systems. Nucleic-acid vaccines are gaining popularity and are believed to be the future of vaccines by many, as they produce strong, long-term immunity and are relatively easy and inexpensive to make.
Stages of Vaccine Development
Developing a vaccine is a rigorous process with lots of research and many human trials, which is important because even a tiny error could hurt someone. This development process has several steps; let’s take a close look at these steps.
Preclinical Testing
This stage is when scientists figure out what antigen their vaccine is going to use. To choose an antigen, scientists test all of them, typically on cells and then animals like monkeys and mice, and choose the one with the best immune response and protection.
Phase 1
During Phase 1, a vaccine is tested on a small group of adults, typically between 20 to 80 people, to test its safety and dosage and confirm that it triggers an immune response.
Phase 2
In Phase 2, the vaccine is given to hundreds of people separated into diverse groups based on characteristics like age and physical health. These trials provide further insight into a vaccine’s safety and ability to generate an immune response.
Phase 3
In this phase of clinical testing, the vaccine is given to thousands of people. Scientists compare how many people become infected by the virus after receiving the vaccine or a placebo. These trials reveal rare side effects and allow researchers to evaluate effectiveness.
Approval
After passing all three phases of testing, vaccines can be approved for early/limited or full use on regular people. Also, after approval, some vaccines enter Phase 4, in which scientists test long-term effectiveness.
How Effective are Current Vaccines?
Right now, we are all focused on a vaccine for COVID-19, and for good reason, but it not the only vaccine in the world. Here, let’s look at the current status of vaccines for some prevalent viruses (including the novel coronavirus).
SARS-CoV-2 (a.k.a. COVID-19)
COVID-19 has given scientists the unique task of developing a vaccine, which typically takes years to research and create, in just a couple of months. This means faster research and rapid testing, and so far, it seems like companies are doing fairly well. Here is a brief list of companies that are making each type of vaccine:
- Virus vaccines: Sinopharm, Sinovac Biotech, Bharat Biotech, Russian Academy of Sciences
- Viral-vector vaccines: CanSino Biologics, Gamaleya Research Institute, Johnson & Johnson, AstraZeneca and University of Oxford
- Protein-based vaccines: Novavax, Medicago, Anhui Zhifei Longcom, Vector Institute (Russian research center), University of Pittsburgh
- Nucleic-acid vaccines: Moderna and National Institutes of Health (United States), Pfizer and BioNTech, Zydus Cadila, CureVac, Imperial College London
Currently, the front-runners for an effective COVID-19 vaccine are Pfizer and Moderna. Moderna’s primary efficacy analysis of their Phase 3 study shows that their vaccine was 94.1% effective, while Pfizer and BioNTech’s primary analysis of their Phase 3 study found that their vaccine had an efficacy rate above 90%.
Some companies like CanSino Biologics, Sinopharm, and the Vector Institute have already had their vaccines approved for early or limited use in countries like China, Russia, and the U.A.E. This makes many experts worry that this rushed process could have dangerous effects in these countries.
Influenza (Flu)
The flu vaccine has been available to people for many years, but the debate of whether or not these vaccines work has pushed anti-vaxxers away. According to the CDC, only half of the U.S. population received a flu shot in the 2018–2019 flu season, which begs the question: is the vaccine effective? Not necessarily, but it’s much better than being without it.
On average, the flu vaccine is 40% effective, which means that it has prevented the flu 40% of the time. Why? The flu has several strains, and the number of strains increases as genetic mutations occur, which are not very rare. Because the virus keeps evolving, we need to get a new vaccine every year to make sure we can fight off the new strains, but one vaccine can’t protect you from all of them. That’s why most flu vaccines can’t guarantee protection, but this is no reason to avoid vaccination.
Ebola
Ebola is a rare and deadly disease that is mainly seen in sub-Saharan Africa and was a dangerous epidemic from 2014–2016. A vaccine was needed to prevent thousands of deaths in Africa, and eventually, an effective one was created. In December 2019, the FDA approved the world’s first Ebola vaccine, but how effective is it? 100% in preventing cases with symptoms appearing after 10 days of vaccination, according to a study conducted during the Ebola outbreak. Vaccine technology is improving, and we can definitely see this advancement with the Ebola vaccine.
Viruses are an interesting field of study. They don’t qualify to be considered living, but they aren’t completely dead either. They have relatively simple cellular structures, but they are extremely diverse. Not all viruses are dangerous, but those that are find ways to infect our bodies and evade our immune systems, so it’s up to us to figure out how to fend them off. The vaccine, which was invented in 1796 by Edward Jenner, has revolutionized the health industry, and without it, millions of people would die from deadly viruses. As research for the COVID-19 vaccine continues, all we can do is stay informed and trust that researchers are doing their job properly, and hopefully, science will prevail in the end.
