I am a research physician and infectious disease specialist at the University of Virginia, where I care for patients and lead a research group on COVID-19. On many occasions, people ask me how I can be so sure that a successful vaccine will be produced that will allow us to avoid COVID-19. After all, we still don’t have one for HIV, which is the virus that causes AIDS.
Next I will explain to you where science is right now, where we will be in five months and why we must rely on the development of an effective vaccine against COVID-19.
1. The human immune system cures COVID-19
In 99% of all COVID-19 cases, patients outgrow the infection and the virus clears the body.
In some of the people who have tested positive for COVID-19, the virus can remain in the body at a very low level for up to three months after overcoming the infection. However, most of these patients stop transmitting the virus to others within 10 days of contracting the disease.
For this reason, it should be much easier to develop a vaccine for the new coronavirus than for other infections such as HIV, since in these cases the immune system cannot cure the disease naturally. SARS-COV-2 does not mutate in the same way as HIV , which greatly facilitates the work of the immune system (which dominates the virus) and the vaccine (which controls it).
2. Antibodies directed at protein S prevent infection
The vaccine will protect, in part, by inducing the production of antibodies against the protein S present on the surface of SARS-CoV-2, the virus that causes COVID-19.
The virus needs protein S to attach itself to , enter human cells, and thus reproduce. Research shows us that antibodies, such as those created by the human immune system, bind to protein S, neutralize it, and prevent the coronavirus from continuing to infect cells in a laboratory culture.
Vaccines in clinical trials are known to increase anti-S antibodies that block virus infection in cells in the laboratory.
At least seven companies have already developed monoclonal antibodies, laboratory antibodies that can recognize protein S. These antibodies are being used in clinical trials to evaluate their power to prevent infection in exposed people, for example through contact. at home.
Monoclonal antibodies are also effective for treatment. During infection, a dose of these monoclonal antibodies could neutralize the virus, giving the immune system the ability to capture and produce its own antibodies to fight the pathogen.
3. Glycoprotein S has vulnerabilities
Protein S has many sites that antibodies can bind to to neutralize the virus. And that is great news, since, with so many vulnerable points, the virus will have a very difficult time mutating to avoid the vaccine.
Many parts of the S protein would have to mutate to avoid neutralizing anti-S antibodies. Too many mutations in protein S would modify its structure and make it unable to bind to ACE2, key to infecting human cells.
4. We know well how to make a safe vaccine
The safety of the new vaccine for COVID-19 will be higher since researchers already know the possible side effects of the vaccine and know how to avoid them.
A side effect observed in the past was antibody-dependent amplification of infection. This happens when antibodies do not neutralize the virus, but instead allow it to enter cells through an antibody receptor. Research has found that when immunized with protein S, higher levels of neutralizing antibodies are produced. And this reduces the risk of amplification.
Another possible problem seen with some vaccines was an allergic reaction leading to lung inflammation, as found in some of the patients who received the respiratory syncytial virus vaccine in the 1960s. This is a dangerous side effect since inflammation in the lungs makes it difficult to breathe. However, our scientists today know how to develop vaccines to avoid this allergic response.
5. There are several different vaccines in development
The United States 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 United States Government is making a huge investment, putting billions of US dollars into seven different vaccines against COVID-19.
By supporting the development of different vaccines for COVID-19, the Government is trying to play it safe and cover all fronts. It is enough for one of these vaccines to be safe and effective in clinical trials for Americans to have a COVID-19 vaccine by 2021.
6. The vaccines are passing phases I and II of the trials
Phases I and II of the trials are used to see if a vaccine is safe and if it triggers an immune response. The results available to date are promising in the case of three different vaccines, since all of them make the levels of production of neutralizing anti-S antibodies double and even quadruple those observed in patients who have overcome COVID-19 .
Moderna, Oxford and the Chinese company CanSino have already demonstrated the safety of their vaccines in phases I and II of clinical trials.
7. Phase III of clinical trials is underway
During phase III of a trial, which is the last step in the vaccine development process, the vaccine is tested in tens of thousands of people to determine if it works to prevent SARS-CoV-2 infection and to decide if it is. safe.
The vaccine developed by Moderna and NIH and the vaccine from Oxford-AstraZeneca began phase III trials last July. The other vaccines for COVID-19 will enter phase III very soon.
8. Accelerate vaccine production and distribution
Operation Warp Speed is giving money to produce millions of doses of vaccines and manufacture them on an industrial scale, even though researchers have not even demonstrated their efficacy and safety yet. The advantage of this strategy is that once a vaccine is safe in phase III trials, stocks are available and vaccines can be distributed immediately without compromising a full evaluation of their safety and efficacy.
This is a more prudent and cautious approach than that of Russia, which is vaccinating its population before demonstrating the safety and efficacy of the phase III vaccine.
9. Vaccine distributors are now being hired
McKesson Corp., the largest vaccine distributor in the United States, has already been contracted by the Center for Disease Control and Prevention to distribute a COVID-19 vaccine to all parts of the country (including clinics and hospitals) where the vaccine will be administered.
Therefore, I believe that we can be sure that at some point in late 2020 we will already know if any of the vaccines for COVID-19 are safe , we will know their effectiveness and we will be clear about which one should be used to vaccinate the population ( at least the American one) in the year 2021.
William Petri, Professor of Medicine, University of Virginia
This article was originally published on The Conversation. Read the original.
