The following are a few links to begin to answer to the question of why there is as yet no available effective vaccine for the COVID-19 causing virus, SARS-CoV-2.
Xeno’s Notes: Why No Vaccine Yet?
updated 5/26/2020
Human trials for a coronavirus vaccine, NVX-CoV2373, will begin in Australia today (5/26/2020) with 130 healthy volunteers aged 18 to 59 trialing a new drug. The testing will mark the first human trial of a COVID-19 vaccine in the Southern Hemisphere and will take place at Melbourne’s Alfred Hospital. The vaccine was developed by American biotech company Novavax. {StationGossip}
A vaccine would provide some protection by training people’s immune systems to fight the virus allowing lockdowns to be lifted more safely, and social distancing to be relaxed. {BBC}
SARS-CoV-2 is a single stranded RNA virus. {NIH}
An RNA virus is a virus that has RNA (ribonucleic acid) instead of DNA as its genetic material. {Wiki}
While efficient vaccines are available for some RNA viruses, in many instances and for different reasons (technologic restrictions, economic facts, etc.), they are scarcely used in the field, and, even more, for many of them, no licensed vaccines are available. {MDPI}
The flu virus, for which we do have a vaccine, is not a Coronavirus, but like Coronavirus it is also an enveloped RNA virus that attacks the respiratory system. Influenza viruses A, B, C, and D are very similar in overall structure to each other with a central core containing the viral RNA genome which tends to be single stranded but in special cases is double. The flu virus is physically slightly elongated, not spherical like a Coronavirus. {Wiki}
The majority of RNA viruses that infect humans are zoonotic, meaning that they can infect vertebrate hosts other than humans. {NIH}
China shared publicly the full RNA sequence of the SARS-Cov-2 virus. {BBC}
For SARS 1 in 2003, it took four months before the genome sequence of the coronavirus was available to develop antigens that could be used for animal and cell culture trials. {SCMP}
Viral vaccines contain either inactivated viruses or attenuated (alive but not capable of causing disease) viruses. {Drugs}
Edward Jenner’s innovations, begun with his successful 1796 use of cowpox material to create immunity to smallpox, quickly made the practice widespread. His method underwent medical and technological changes over the next 200 years, and eventually resulted in the eradication of smallpox. {HistoryOfVaccines}
Variola is a large brick-shaped virus measuring approximately 302 to 350 nanometers by 244 to 270 nm, with a single linear double stranded DNA genome 186 kilobase pairs (kbp)… {Wiki}
At Inovio’s lab in San Diego, scientists use a relatively new type of DNA technology to develop a potential vaccine. “Once China had provided the DNA sequence of this virus, we were able to put it through our lab’s computer technology and design a vaccine within three hours.” … There are no guarantees any of the designs so far will be safe and effective enough to be used – 1/30/2020 {BBC}
RNA viruses mutate at a rate up to a million times higher rate than their hosts. {PLOS}
Having only a single strand makes it easier for RNA to get cut up and remixed because only one connection needs to be broken. This means viruses can mutate really quickly, which could potentially make any cure or vaccine obsolete over time. {TheHill}
SARS and the new SARS-CoV-2 share about 80-90 percent of their genetic code.
In 2004, U.S. researchers successfully gave a SARS vaccine to mice in a trial. The researchers later exposed these mice to the actual SARS vaccine; they found that these mice had very few virus particles in their lungs compared to mice who never received the SARS vaccine. This type of vaccine is much safer than other vaccines that are commonly used, as it uses DNA, rather than killed forms of the actual virus, such as in the conventional flu vaccine. {HowStuffWorks}
In China, in 2004, researchers successfully vaccinated people with the SARS vaccine. They found that there were very few side effects associated with the SARS vaccine. {HowStuffWorks}
To understand the virus’s characteristics and behavior in humans we must first develop an animal model. {SciAlert}
Ferrets, a popular model for influenza and other respiratory infections, are susceptible and the world’s first animal studies involving multiple vaccines has started in India. Ferret lung physiology is similar to humans. {NatureAsia}
Australian scientists have begun injecting ferrets with two potential vaccines. It is the first comprehensive pre-clinical trial to move to the animal testing stage, and the researchers say they hope to move to the human testing stage by the end of April. {BBC}
On Monday, April 13, I’m getting a COVID-19 vaccine. If you’re thinking, “There is no vaccine right now,” you’re right. I’m one of 45 volunteers who was selected to be part of a clinical trial with The University of Washington. {Yahoo}
Some vaccine scientists are lifting small sections of the coronavirus’s genetic code and putting it into other, completely harmless, viruses…. you can “infect” someone with the harmless bug and in theory give some immunity against infection. {BBC}
The National Institutes of Health announced that Kaiser Permanente has begun the first clinical trial of a COVID-19 vaccine, called mRNA-1273. Scientists estimate that it will take at least one year to make a COVID-19 vaccine available to the general public. {JHU}
Even if the clinical trial of mRNA-1273 is successful, the COVID-19 vaccine will not be available for the next 12-18 months. March 17, 2020 {TravelMedia}
Currently, around 40 companies are rushing to produce a vaccine against the Covid-19. Four of those companies already started testing vaccines on animals, and one of them could even begin human trials reasonably soon. March 29, 2020. {WorldAtlas}
There are no Food and Drug Administration-approved vaccines or therapies for the disease although the regulator on March 29 granted an emergency use authorization to hydroxychloroquine sulfate and chloroquine phosphate to treat COVID-19 patients. April 11, 2020 {MarketWatch}
U.S. health officials are fast-tracking work on a coronavirus vaccine, hoping to start human trials within the next three months. Jan 31, 2020 {CNBC}
Even fast tracked, the fastest researchers could get a vaccine for the current outbreak to market, assuming they find something that works and has no major complications, would be a year, said Peter Hotez, co-director of Texas Children’s Hospital Center for Vaccine Development, who helped develop a vaccine candidate for SARS. {CNBC}
“We may have a vaccine in record time,” former FDA Commissioner Scott Gottlieb said. … “We are light years beyond where we were in biomedical technology than during SARS” {CNBC}
“… vaccines contain other ingredients that make them safer and more effective, including preservatives, adjuvants, additives and residuals of the vaccine production process. Because specific ingredients are necessary to make a vaccine, even though they are eventually removed, trace amounts can still remain. These residuals can include small amounts of antibiotics and egg or yeast protein…. thimerosal, an organic form of mercury (also called ethylmercury) that prevents vaccines from being contaminated. This form of mercury is different from methylmercury, which can damage the nervous system. Although thimerosal has been shown to be safe, now all routine childhood vaccines are produced in thimerosal-free form.” {NY.GOV}
Reason not to rush at any step, there is a historical worst case vaccine scenario: The “Cutter Incident” in 1955 involved a flaw in the Salk polio vaccine manufacturing process at Cutter Laboratories that led to production of substantial amounts of what was thought to be inactivated vaccine that contained live poliovirus. The result has been called “…one of the worst pharmaceutical disasters in US history”[11], with 40,000 cases of polio resulting in 51 cases of permanent paralysis and five deaths among vaccinated individuals, and 113 cases of paralysis and five deaths among contacts of vaccinated individuals [11,12]. As a result of the Cutter Incident, the US government implemented much more vigilant monitoring and regulation of the vaccine industry [13]. {NIH}
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