Novel coronavirus vaccine: more than 100 kinds are under development and 8 kinds are in clinical trials
The clearest way to get rid of the novel coronavirus crisis is to develop a safe and effective vaccine. Scientists have not wasted any time and have been working hard. At least 102 candidate vaccines are under development worldwide, and eight of them have been tested in humans. At least two monkeys have been protected from novel coronavirus (sars-cov-2), which causes novel coronavirus.
Some optimistic vaccine developers said that if everything goes well, we may see large-scale production and limited vaccine deployment as early as this autumn. If true, it would be an extraordinary achievement. Less than four months ago, sars-cov-2, an unnamed and never seen virus, suddenly appeared in Wuhan, a city in Central China. Researchers there quickly discovered it and deciphered and shared its genetic code in late January, enabling researchers around the world to work hard to defeat it. By late February, many researchers were conducting clinical trials for candidate vaccines. By the middle of March, two of them started to take action, and the volunteers began to receive the first batch of candidate vaccines against novel coronavirus.
This is a record setting feat. But it is not clear whether researchers can maintain this breakthrough.
Generally, vaccines must undergo three more rigorous human trial phases before they are considered safe and effective. These phases assess the safety of candidates, the intensity of the immune response they trigger, and their ability to actually protect people from infection and disease.
Most candidate vaccines have failed to do so. It is estimated that more than 90% of the candidates failed. Although it is conceivable that the schedule of the novel coronavirus pandemic may deliver vaccines in a short period of 18 months, most vaccines take several years (in fact, usually more than 10 years) to get from the preclinical review to the syringes in the doctor’s office.
Cancelling this schedule may increase the risk of failure. For example, candidate vaccines usually enter the three stages of clinical trials only after they have been fully tested in laboratory animals that can simulate human diseases. However, no animal model of novel coronavirus has been established for this new virus. In a catastrophic pandemic, there is not enough time to fully develop vaccines. Now, some researchers are working on ground animals at the same time as human experiments.
Researchers have reason to worry about the safety of any novel coronavirus vaccine. When they tried to make vaccines against some coronavirus relatives of sars-cov-2 in the past, they found that candidate vaccines seemed to worsen the infection in a few cases. That is, these candidate vaccines seem to promote the immune response of rabies, causing lung damage in monkeys and liver damage in ferrets. Researchers still do not fully understand this problem, nor do they know whether it may occur in humans, let alone whether it will appear with a new candidate vaccine against sars-cov-2.
RNA and DNA vaccines: These are the latest types of vaccines and the most unstable. There are currently no licensed vaccines using this method. But researchers are optimistic about its potential.
Moderna cooperated with the National Institutes of health to conduct a clinical trial in February, and the first dose of treatment was given to humans on March 16. If everything goes according to plan, the company suggests preparing vaccines for front-line medical personnel by the fall of this year.
At the same time, cansino biologics, a Chinese biotechnology company, began testing its candidate vaccine based on viral vectors on March 17. This strategy packages the genetic material of sars-cov-2 into a weakened adenovirus strain, and the company has started phase II trials.
Sinovac biotech, headquartered in Beijing, made headlines this month after its whole virus inactivated sars-cov-2 vaccine candidate was proved to protect a few monkeys from novel coronavirus in early laboratory tests. Its first phase of human clinical trial began on April 16. The results are positive, but some researchers are eager to see more testing and safety data.
Researchers at the University of Oxford have also started a good start in developing vaccine candidates based on viral vectors. They packaged sars-cov-2 spike protein in weakened adenovirus, similar to cansino’s method. Like Sinovac, their vaccine also protected a small number of monkeys in early laboratory experiments. Researchers at the University of Oxford began dosing the participants last week. The researchers told the New York Times that if these trials were carried out as planned, they could produce millions of doses by September.