Why will there be vaccines first before a cure for COVID-19?

Question

I found this link on the internet:

70 vaccines are getting ready for coronavirus: 3 very promising

Why is it that there will be vaccines before a cure? Shouldn't it be the other way around? What is the reason for the vaccine first then the cure?

Answer 1

Your question contains a lot of misconceptions.

• A cure is definitely possible
• A cure could be found, proved, and proved safe, more quickly than a vaccine
• People and firms that could be working on cures are choosing to work on vaccines

None of these are correct. Most virus-caused diseases have no cure: colds, Zika, Dengue, and so on. A tiny handful have treatments that can ease the course of the disease: you've heard of Tamiflu and so on. And some can be actually cured with medication. So the first assumption, that a cure exists to be found, is not a sure thing by any means, and is actually quite unlikely.

Then there is the matter of side effects, unintended consequences, and so on. We are pretty familiar with vaccinations by now. We know how to test that a vaccine doesn't cause other problems. But a cure often can have really bad effects. A drug that is supposed to lower your [blood pressure, heart rate, blood sugar, whatever] or raise your [immune response, whatever] might raise or lower it too much. It might cure one thing but give you a stroke or a heart attack. The immunotherapy that cured my 3-months-to-live melanoma also wiped out my thyroid and nearly killed me with a skin reaction. [I am fine with that trade, but the point is treatments can and do kill people. We only use them if the curing outweighs what the side effects do.] Cures have to be tested to understand all of these possibilities. In most cases we want to know the long term reactions -- and that means giving the drug and monitoring and studying for months or more. Plus, we give treatments to sick people, but vaccines to healthy people, so the side effects are even more of a big deal for a treatment.

And finally, the money and teams to work on a vaccine are entirely different than the money and teams who work on cures. So work is underway on cures too. It hasn't been set aside to focus on vaccines.

What you're observing is that everyone predicts a vaccine will come more quickly. It's a better understood area (we have vaccines for tons of viruses, but cures for very few) with less concern about hurting or killing the people we give it to. It's most likely the vaccine teams will succeed before the cure teams do. But it's not because there isn't any work happening on possible cures.

Answer 2

Drugs are typically small molecules that interfere with some chemical process in the disease causing microbe, and therein lies the rub. Bacteria, fungi, protozoa, worms, etc. are sustained by their own complex systems of chemical reactions, largely independent of chemical systems that sustain us. That makes it easier to find a chemical that attacks something in the microbe's chemistry, but doesn't affect our own chemistry (much). Penicillin for example, targets an enzyme bacteria use to maintain their cell walls. Our own cells don't have cell walls in the same way bacteria do, and we don't use that enzyme, so a drug that blocks that enzyme in bacteria may cripple the bacteria without having (much) of an effect on our own cells.

Viruses on the other hand, are really just a bit of DNA or RNA wrapped in a coat of sugars, proteins, and fats. They don't have any life processes of their own. They simply piggy-back and subvert our own chemical systems. That means any drug that targets a chemical process used by the virus is likely to have bad side effects on the patient too. In some cases it is possible to create an anti-viral drug that attacks a protein unique (or mostly unique) to the virus. The problem is that this is a much narrower range of possible targets, and it tends to be specific to a single virus. Drugs like penicillin often work on whole families of bacteria. This is what makes finding a drug that "cures" viral diseases so hard.

However, living creatures have had to defend themselves against viruses for billions of years, so we've evolved sophisticated internal defenses against them. Even bacteria have a sort of immune system against viruses. When you are infected with a virus your body begins a race to mount an effective immune response before the virus does severe or even fatal damage to your body. Vaccines allow your body to begin mounting an immune response before you are actually exposed to the virus. Then if you are eventually exposed your immune system is able to shut the virus down much more quickly. Getting a workable vaccine is still tricky though, because you have to find substances that starts an immune response specific to the target virus in most people, but that doesn't also kick the immune system into an over reaction that itself can be very dangerous.

Answer 3

I don't believe we have the data to say that vaccines will be deployed earlier than an effective treatment.

Vaccine technology is old technology and the go to for most infectious diseases as there is a desire to prevent preventable illness. However, HIV was discovered in 1984 but we still don't have a vaccine against it though we have effective treatments. Some of the problems with a vaccine for HIV is that it's not a respiratory virus, and it mutates rapidly.

The SARS epidemic was in 2003 and we still also don't have a vaccine for that, and it's unclear if the new mRNA vaccines for COVID-19 will be effective or not as there has not been one deployed successfully before.

Most of our drugs used in treatment are small molecules but many of our modern biological drugs are synthetic humanised antibodies, and there is a lot of experience in developing such treatments in diseases such as Rheumatoid Arthritis, and Axial spondyloarthropathies.

To develop such antibodies to fight COVID-19 an animal (mouse) can be infected with SARS-CoV-2 and the subsequent antibodies are screened for effectiveness. Those most promising are humanised and then further developed for testing. Celltrion are using antibodies taken from recovered Korean patients.

Through a partnership with the Korea Centers for Disease Control and Prevention (KCDC), Celltrion initially identified and secured 300 different types of antibodies that bind to the SARS-CoV-2 antigen. These were then screened based on their ability to bind to the virus Spike (S) protein. Celltrion was then able to capture a total of 38 potent neutralising antibodies, of which, 14 were identified as most potent against SARS-CoV-2.

...

Ki-Sung Kwon, Head of R&D Unit at Celltrion said: “We are bringing our full resources and expertise to overcome this global health crisis and are glad to have identified these antibodies sooner than previously expected. These antibodies can recognise multiple epitopes, thus increasing the probability of neutralisation against viral mutations. Given the expedited development process of our antiviral antibody treatment, we anticipate moving to first-in-human clinical trials in July. We are also on track with the development of a ‘super antibody’ or ‘an antibody cocktail’ and the launch of a rapid diagnostic kit in the summer of this year.”

These would be expected to work like naturally developed antibodies that develop during the adaptive immune response to fight the infection.

https://www.drugtargetreview.com/news/60206/celltrion-selects-14-lead-monoclonal-antibodies-for-covid-19-treatment/