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AWith fall fast approaching, many wonder if the race for a vaccine will pay off starting in January 2021.
I am a physician-scientist and infectious disease specialist at the University of Virginia, where I care for patients and conduct research on COVID-19. I am occasionally asked how I can be sure that researchers will develop a successful vaccine to prevent COVID-19. After all, we still don’t have one for HIV, the virus that causes AIDS.
This is where the current research is, where I think we will be in five months and why you may be optimistic about delivering a COVID-19 vaccine.
1. The human immune system cures COVID-19
In up to 99% of all COVID-19 cases, the patient recovers from the infection and the virus is cleared from the body.
Some of the people who have had COVID-19 may have low levels of the virus in the body for up to three months after infection. But in most cases, these people can no longer transmit the virus to others 10 days after they became ill.
Therefore, it should be much easier to make a vaccine for the new coronavirus than for infections such as HIV, where the immune system fails to cure it naturally. SARS-CoV-2 does not mutate like HIV does, making it a much easier target for the immune system to control or for the control of a vaccine.
2. Antibodies targeting the spike protein prevent infection
A vaccine will protect, in part, by inducing the production of antibodies against the spike protein on the surface of SARS-CoV-2, the virus that causes COVID-19.
The virus needs the spike protein to adhere to and enter human cells in order to reproduce. Researchers have shown that antibodies, such as those produced by the human immune system, bind to the spike protein, neutralize it, and prevent the coronavirus from infecting cells in laboratory culture.
Vaccines in clinical trials have been shown to generate anti-spike antibodies that block virus infection in laboratory cells.
At least seven companies have developed monoclonal antibodies, laboratory-made antibodies that recognize the spike protein. These antibodies are entering clinical trials to test their ability to prevent infections in those who are exposed, for example through household contact.
Monoclonal antibodies can also be effective for treatment. During an infection, a dose of these monoclonal antibodies could neutralize the virus, giving the immune system a chance to catch up and make its own antibodies to fight the pathogen.
Read also: Why herd immunity to Covid-19 may be closer than we thought until now
3. The peak glycoprotein contains multiple targets
The spike protein has many locations where antibodies can bind and neutralize the virus. That’s good news because with so many vulnerabilities, it will be difficult for the virus to mutate to avoid a vaccine.
Various parts of the peak would need to mutate to evade neutralizing anti-peak antibodies. Too many mutations in the spike protein would change its structure and render it unable to bind to ACE2, which is key to infecting human cells.
4. We know how to make a safe vaccine
The safety of a new COVID-19 vaccine is improved if researchers understand the potential side effects of the vaccine and how to avoid them.
A side effect seen in the past was an increase in antibody-dependent infection. This occurs when the antibodies do not neutralize the virus, but instead allow it to enter cells through a receptor intended for the antibodies. Researchers have found that immunizing with the spike protein can produce high levels of neutralizing antibodies. This reduces the risk of improvement.
A second potential problem posed by some vaccines is an allergic reaction that causes inflammation in the lung, as seen in people who received a respiratory syncytial virus vaccine in the 1960s. This is dangerous because inflammation in the air spaces of the lungs can make it hard to breathe. However, researchers have now learned to design vaccines to avoid this allergic response.
5. Several different vaccines in development
The US government is supporting the development of several different vaccines through Operation Warp Speed.
Operation Warp Speed’s goal is to deliver 300 million doses of a safe and effective vaccine by January 2021.
The US government is making a huge investment, committing $ 8 billion for seven different COVID-19 vaccines.
By backing multiple COVID-19 vaccines, the government is hedging its bets. Only one of these vaccines needs to be shown to be safe and effective in clinical trials for a COVID-19 vaccine to be available to Americans in 2021.
6. Vaccines that go through phase I and II trials
Phase I and Phase II trials test whether a vaccine is safe and induces an immune response. The results to date from three different vaccine trials are promising as they trigger the production of anti-spike neutralizing antibody levels that are two to four times higher than those seen in people who have recovered from COVID-19.
Moderna, Oxford and the Chinese company CanSino have demonstrated the safety of their vaccines in phase I and phase II trials.
7. Phase III clinical trials are underway.
During a phase III trial, the final step in the vaccine development process, the vaccine is tested in tens of thousands of people to determine if it works to prevent infection with SARS-CoV-2 and if it is safe.
The vaccine produced by Moderna and NIH and the vaccine from Oxford-AstraZeneca began phase III trials in July. Other COVID-19 vaccines will begin phase III in a few weeks.
8. Acceleration of vaccine production and deployment
Operation Warp Speed pays for the production of millions of doses of vaccines and supports the manufacture of vaccines on an industrial scale even before researchers have demonstrated the efficacy and safety of vaccines.
The advantage of this strategy is that once a vaccine is shown to be safe in phase III trials, there will already be a stockpile and can be immediately distributed without compromising the full evaluation of safety and efficacy.
This is a more prudent approach than that of Russia, which is vaccinating the public with a vaccine before it has been shown to be safe and effective in phase III.
9. Vaccine distributors are being hired
McKesson Corp., the largest vaccine distributor in the US, has already been contracted by the CDC to distribute a COVID-19 vaccine at the sites, including clinics and hospitals, where the vaccine will be administered.
I think it’s realistic for us to know sometime in late 2020 if some COVID-19 vaccines are safe, exactly how effective they are, and which ones should be used to vaccinate the US population in 2021.
William Petri, Professor of Medicine, University of Virginia
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Read also: New study says flushing urinals can also release clouds of coronavirus-laden aerosols
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