With Covid-19 now reaching its eighth month of plaguing the world, you may be asking yourself, where is the vaccine? The good news is that currently there are 126 vaccines being currently tested around the world. One of them is going into its final stage of testing with 30,000 participants. The bad news is that with viruses such as this in the past, the vaccine has taken years if not decades to create. Dengue for example was first identified in 1943 but the very first vaccine was only just approved last year according to the federal food and drug administration. Even more worrying is the success scientists have had with finding a vaccine for previous coronaviruses. Sars, for example, never got a licensed vaccine and neither has Mers. This is partly due to the fact that Sars seemed to just fade away and Mers is only regional. Hopefully, with the extent to which Covid-19 has affected the world, scientists will try harder than ever before. Not only this but research already conducted for Sars and Mers will continue to help scientists with this current outbreak of coronavirus.
Coronavirus vaccines are extremely hard to create for three reasons, reinfection, mutation, and safety of the vaccine, as I shall explain here. The immune response to coronaviruses is so weak that people can get reinfected within a year of originally catching the virus, according to the national library of medicine. Researchers at Oxford University found through blood tests of recovered Covid-19 patients that levels of IgG antibodies (those required for long-lasting immunity) faded within a month of recovery from the virus. This means that vaccines may struggle to create immunity for much longer than a year. Genetic mutations of a virus may cause vaccines to become completely ineffective, so the genetic stability of Covid-19 is another factor that needs to be considered when discussing vaccines. Previous coronaviruses such as Sars have seemed to be stable but the professor of emerging infectious diseases at the London School of Hygiene and Tropical Medicine has said that the mutations of Covid-19 he has already witnessed are “an early warning”. The final difficulty is the safety of the vaccine. Due to the fact that the vaccine will be distributed to billions of healthy people, any side effect could be a colossal fault. One candidate for a vaccine of Sars even ended up giving a ferret hepatitis! These struggles, however daunting they are, are not discouraging many biotech firms from working toward a vaccine.
Firms that are working toward a vaccine are split into two schools of thought. One idea is to stick to tried and true methods due to the fact that the infrastructure for the production of these vaccines exists, so it will be easy to distribute. The other is to use unprecedented techniques that may be better suited to the unprecedented virus that is Covid-19.
All of the firms working with the ‘old school’ technique are based in China and they only consist of 4 vaccine candidates, the other 126 candidates are all using the new techniques. This old school method of creating vaccines is to grow a strain of the virus in the laboratory and then break the virus down using heat or chemicals, therefore making it unable to replicate. This is then injected as a vaccine and the human body itself makes the antibodies. The body is not affected by the virus as it is inactive and unable to replicate in the body. The firms who are aiming to use this method feel it is best as there is already infrastructure around the world that is capable of producing the vaccine and therefore it will be available around the world more readily once it is found. The drawback is that, as discussed earlier, the human body does not seem to create long-lasting immunity to the virus itself, meaning that it is currently speculated that even if this method proved to be successful, the vaccine would only last a year before its effects wear off. This would mean that this type of vaccine would not be capable of eradicating the worldwide threat of Covid-19. A vaccine like this could also lead to what is known as enhanced disease response. Enhanced disease response could lead to more serious respiratory problems caused by the virus. Scientists agreed that this is a theoretical concern but it can not be ruled out until vaccinated people have been exposed to the disease.
The other 122 vaccine candidates use new technologies that, in most cases, have never been used before. An example of this is nucleic acid vaccines that are based on genetically engineered virus DNA. This technique was founded when scientists discovered that the injection of plasmid DNA that has no associated protein, carbohydrate, or lipid could induce an immune response. This immune response, while seemingly less efficient, has advantages over that normally produced with older vaccine methods and may be the key to lasting immunization against coronaviruses. While this technique is experimental it is proving successful as US biotech company Moderna is in the lead with its mRNA vaccine heading into the final stage of the clinical trial with 30,000 participants.
So while we shouldn’t hold our breath for a vaccine, we can at least be thankful we aren’t one of the test ferrets.
Restifo, N P, et al. “The Promise of Nucleic Acid Vaccines.” Gene Therapy, U.S. National Library of Medicine, Jan. 2000, www.ncbi.nlm.nih.gov/pmc/articles/PMC2241736/.
Ma, Josephine. “Can China Win Covid-19 Vaccine Race with Old School Technology?” South China Morning Post, 19 June 2020, www.scmp.com/news/china/science/article/3089356/can-china-win-covid-19-vaccine-race-old-school-technology?onboard=true.