In the first article we looked at face masks (when do you need to where one and why?); in the second we looked at disinfection (which disinfectants work best?); and the third topic was social distancing (why is 2 metres considered to be a safe distance?) The subject matter for the fourth article was the lockdown and whether the idea of an ‘immunity passport’ is a good idea (which is probably isn’t). For the firth dive into COVID-19 subjects, we look at where we are with vaccine development, what the most promising antivirals are, and what do the different tests for coronavirus do and how do they vary?
In this article, the topic is testing, vaccines and other efforts to help to combat the disease.
With testing, there are three broad areas:
Reverse transcription-polymerase chain reaction tests
Here samples are collected by swabbing the back of the patient’s throat or nose using a long thin swab. Then the virus’s ribonucleic acids are copied millions to billions of times to amplify the signal and detect the virus. These types of tests can take several hours to complete and there is concern over shortages of reagents needed to perform the tests.
Antibody or serology tests
With these types of tests, antibody tests are performed on the patient’s blood, which can be obtained from a finger prick. The blood is the analysed for the presence of antibodies produced by the body to fight off SARS-CoV-2. While results can be provided in a matter of minutes; however, in recent days concerns have been raised regarding the reliability of these tests.
Antigen tests
For antigen tests the patient puts a sample, such as a throat swab, onto a special strip, the colour of the strip changes if SARS-CoV-2 is present. An antigen is a foreign substance present in the body. These forms of tests look for the corona spike proteins. Currently, these tests are less proven and unreliable and are not currently available to consumers.
Vaccines
As part of a major global effort thousands of researchers and clinicians worldwide areracing against time to develop cures, vaccines, and better diagnostic tests for COVID-19, the illness caused by the virus SARS-CoV-2. To date, over 1,700 articles on COVID-19 are already listed in databases like Google Scholar, and these are being added to at a rapid rate.
With vaccines, the most successful appear to be those that carry the Receptor Binding Domain (of the virus‘s S-protein), which allows the virus to bind to and fuse with host cells. Besides the traditional live attenuated, inactivated, and subunit-based vaccines, modern types such as DNA/RNA-based and nanoparticle- or viral vector-borne vaccines are also being considered.
Vaccine development is a slow process. The development and testing of new vaccines takes one to several years, so other approaches are essential in the meantime.
Antivirals
In terms of combating the coronavirus in the shorter term, the research consensus at present points to the most promising approaches for fast progress are selected antivirals such as remdesivir (developed by the biopharmaceutical company Gilead Sciences).
With broad-spectrum antivirals in general, most are nucleoside analogs. These drugs mimic the bases in the virus’s RNA genome and get mistakenly incorporated into nascent RNA chains, stalling the viral copy process. However, because coronaviruses have a so-called “proofreading” enzyme which can cut such mismatches out, most nucleoside analogs don’t work all that well.
This is where remdesivir comes in, which works in a different way and it is a good candidate.
Convalescent blood plasma
This is plasma donated from patients who have recovered from coronavirus. Within a given window, the plasma will contain low levels of a set of antibodies that should work against the virus. Blood plasma is a yellowish liquid that makes up about half of the blood volume. After a virus, a person’s plasma contains antibodies that are used to help fight infection.
Alternatives
An alternative to blood plasma are monoclonal antibodies, which can be isolated and the mass-produced through biotechnology. However, these types of products can take a long time to develop. Other things being worked on are fusion inhibitors, inhibitors of human proteases, and immune modulators such as corticosteroid hormones.
There is also gene therapy, which is a potential alternative to be used until a vaccine is available. For example, there is a form of gene therapy delivered through the adeno-associated virus vector. This would entail the fast, targeted delivery of antibodies, immune-adhesins, antiviral peptides, and immune-modulators to the upper airways. Many scientists think this will provide short-term protection.
The video below expands on some of the subjects covered in this article:
As an example of how all of this research can be made sense of, the publication Frontiers in Microbiology, has a useful article titled ‘The Current and Future State of Vaccines, Antivirals and Gene Therapies against Emerging Coronaviruses’, provides a good summary.
