I’ve seen a lot of confusion regarding the different types of therapies are being tested for covid-19. For the people who wants to invest in companies that are developing new therapies for Covid, read this first.
This is a list of different type of therapies which have been tested or are under development.

Antibody therapies and plasma therapy

Antibodies are small molecules produced by our own immune system. During infection, the immune system is trained to produce antibodies which can target viruses. These antibodies can be found in the plasma of patients who recovered from the Covid-19. By injecting the plasma to patients with an immune system that is not yet trained to fight coronavirus, we are giving the immune system the weapons to target and neutralize the virus. That’s not the only way we can use antibodies. Antibodies can easily be produced in the lab with different specificity for the targets. For instance, it is possible to generate a large amount of antibodies that block the ACE2 proteins (the molecule targeted by Sars-Cov-2) on the surface of host cell. This way the virus cannot infect the cell. Regeneron Pharmaceuticals created a cocktail of antibodies that target multiple parts of the virus, but with limited effects.

Antiviral therapies

Viruses cannot replicate on their own, they need to take advantage of host molecules to reproduce. Antiviral drugs do not directly target the virus, instead they stop the reproduction of new viruses in the host cells by blocking the interaction between viral and host proteins. There are no new antiviral drugs specific for Sars-Cov-2, instead many pharma are trying to repurpose existing anti-viral drugs for treating Covid-19. An example of this is Gilead’s Remdesivir which was developed to treat HCV and has been authorized for emergency use to treat covid-19 in many countries.

Immunosuppressive therapies

The death from Covid-19 is caused by the so called cytokine storm, which is causing excessive inflammation in the lungs. Cytokines are part of the inflammatory process caused by the immune system to fight infection. To avoid your own immune system to kill yourself, one of the first line of treatment for Covid was to try to stop your immune system to destroy your organs. Dexamethasone is commonly used for its anti-inflammatory and immunosuppressive properties. Another immunosuppressive therapy is Roche’s Actemra. The therapy alone didn’t prove to be effective, but Roche and Regeneron are combining their therapies to obtain better effects.

Vaccines

None of the drugs I mentioned above have a preventive function and are not going to provide immunity from reinfections. In order to achieve full immunization, we need a vaccine. Vaccines can also be further divided into multiple categories, but for sake of simplicity I won’t go into details. The basic mechanism is to present part of the virus to the immune system, which will start an immune response and train immune cell to recognize and destroy the virus, also generating memory cells that can provide long lasting immunity. Given that the immune system is trained to target specific part of the virus, if the virus mutates on those parts, the immune system won’t be able to recognize the virus anymore. This is the reason why we do not have a vaccine for HCV or HIV yet. Luckily, Sars-Cov-2 mutates less frequently than those viruses. Many companies are currently testing their own vaccines, the most two advanced ones are AstraZeneca and Moderna. Check this page for a complete overview of vaccines currently under development www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html

I tried to keep it simple, by doing that I might have wrote something slightly inaccurate. Happy to answer questions or go more in details if you want some extra information.