Viruses are tiny organic structures that are able to invade human cells and multiply inside them. The host cells are either destroyed or at least prevented from performing their normal metabolic functions.

As the replication mechanism of most viruses is highly complex, it is difficult to fight viral diseases and some of the challenges faced by medical researchers are very hard to overcome. This is due mainly to the fact that viruses can utilise various proteins and enzymes of the host cell to produce virus-specific proteins. As such, no default standardised treatment exists for viral infections.

With regard to the new COVID-19 disease, researchers are currently working as quickly as possible on medical measures to combat the SARS-CoV-2 virus. The research is currently focused on three different fields:

1. Testing the effectiveness of various existing approved medications against COVID-19
2. Development of a specific substance against SARS-CoV-2, the virus that causes COVID-19
3. Development of a vaccine against SARS-CoV-2

1. Testing the effectiveness of medications that have already been approved

The focus is on various groups of medication with different treatment principles:

• Antiviral drugs
  These were developed to disrupt the replication mechanism of certain viruses and treat other viral diseases, such as Ebola, hepatitis and HIV.
  
  Key agents that are currently being tested include remdesivir, which was originally approved for the treatment of Ebola, or active agents in the HIV therapy, such as ritonavir and lopinavir.
• Immunomodulators
  Immunomodulators prevent an excessive immune response and are used in the treatment of autoimmune diseases, such as rheumatoid arthritis and multiple sclerosis.
  
  Interferons, biologicals and the corticosteroid dexamethasone in particular are being tested.
• Other medication for treatment of infectious diseases
  These substances were originally approved for the treatment of parasite infections (e.g. malaria), bacterial lung diseases or venereal diseases (e.g. chlamydia infections).
  
  As an example, the malaria drugs hydroxychloroquine and chloroquine are being tested in combination with the antibiotic azithromycin, which is used to treat bacterial chlamydia infections.

Some of these substances have already been used to treat COVID-19 in China and other countries and have been tested in small-scale studies. However, only low numbers of patients were involved in these studies and no comparisons with groups of patients receiving a different treatment were made.

In order to produce more reliable results with regard to effectiveness against COVID-19, patient studies with larger groups of patients in a controlled, randomised setting have been set up. Medical institutions in various countries are now comparing different treatment concepts on different groups of test subjects.

Around 70 countries are participating in the multinational Solidarity study launched by the WHO. Other major studies include the European Discovery study, the British Recovery study and the US Actt study.

2. Development of a specific substance against SARS-CoV-2

Researchers are not focusing exclusively on testing the potential effectiveness of existing antiviral medication against COVID-19. They have started to examine the specific replication mechanisms of SARS-CoV-2 and are trying to identify potential ways of attacking the viral spread.

SARS-CoV-2 uses the transmembrane angiotensin-converting enzyme 2 (ACE 2) and the transmembrane protease, serine 2 (TMPRSS2) of the host cell to form a specific protein. This newly formed S protein enables the virus to invade the host cell and start replicating. Approval has been granted for the first clinical studies to examine whether inhibiting ACE 2 and/or TMPRSS2 can prevent the virus from invading the host cells.

3. Development of a vaccine for SARS-CoV-2

More than 80 vaccine projects have been initiated worldwide since the outbreak of the pandemic. Significant financial support is being provided by the European Commission, the governments of several countries and the Coalition for Epidemic Preparedness Innovations (CEPI). This international initiative has united countries, foundations, research institutions and pharmaceutical companies in an effort to develop vaccines viruses that are very much in the public eye.

The first vaccines are already in phase four of a six-phase development process ranging from the initial analysis of the virus to the widespread distribution of the vaccine.

There are different types of vaccine group:

• Live vaccines
  Harmless living viruses that serve as carriers (viral vectors) are modified to simulate a SARS-CoV-2 infection in the human immune system. This stimulates the production of antibodies against SARS-CoV-2 in order to protect the infected person from a real infection.
• Inactivated vaccines
  These contain parts (viral proteins) of the real SARS-CoV-2 virus in order to stimulate the production of antibodies by the immune system.
• Gene-based vaccines
  These vaccines contain selected modified genes of the SARS-CoV-2 virus that cause the human organism to build up immune protection by creating antibodies.

Medical treatment - a vaccine - how soon?

It remains to be seen whether, ultimately, COVID-19 can be treated, and if so with what type of medication. The first study results from testing approved medication on larger groups of patients are to be expected in autumn 2020.

At the moment, it is unclear whether it will be possible to develop a novel antiviral drug to fight COVID-19 specifically. If a treatment that stops the spread of SARS-CoV-2 were actually found, it would still take a long time before it could be used on a large scale.

We can look forward to the development of an effective COVID-19 vaccine with some optimism. The first vaccines are being tested on volunteers and could potentially be approved for mass production in a few months. However, it will still take time before large-scale vaccine initiatives are possible; after the development and approval of suitable vaccines, development of a huge production capacity will be required.