By Sandra Albert and Glenn Kharkongor
While there are many antibiotics that work effectively against bacteria, the same drugs are not useful in combating viruses. There are only a handful of anti-viral drugs as compared to hundreds of antibiotics. So why the difference?
Bacteria, as school students know, are one-celled organisms that can be found naturally in our bodies and in our environment. Most are harmless and do not cause infection.
Bacteria in our bodies help us to digest food, protect us against other microbes, and provide nutrients for our body.
They reproduce on their own. Bacteria cause skin, ear and throat infections and also more severe diseases like pneumonia, tuberculosis, tetanus and meningitis.
Viruses, on the other hand, cannot live without a host. They are parasites and need another living creature to help them multiply. Viruses are smaller than bacteria and they attach themselves to another living cell and use that cell’s genetic material to reproduce themselves.
Most viruses cause disease. Examples of diseases caused by viruses include common cold, measles, chickenpox and AIDS.
Coronaviruses are a large family of viruses that cause illnesses ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS).
Coronaviruses are zoonotic, meaning they are transmitted between animals and people. They may come from different species of animals. SARS was transmitted from cats and MERS from dromedary camels to humans. COVID-19 is a new strain that was discovered in 2019, not been previously identified in humans. Its animal origin is still unclear.
Vaccines
So far, about 35 companies and research organisations are developing vaccines. US and French companies have begun clinical trials of a new anti-viral that targets the COVID-19. The first human trials began last week in the US. This trial will take several months to complete. The French company will soon start testing on patients in Italy. It may take one and half years at least to distribute the vaccine on a large scale.
In India, the National Institute of Virology in Pune has isolated the virus and is studying its genetic structure, so that the vaccine can be designed accordingly. It is estimated that it will take one and a half years to develop the vaccine in India. The time period, thereafter, for trials and mass manufacturing has not been announced. There will be great competition for the new vaccine and may not be accessible for poor patients. So, it is important for India to develop its own vaccine.
Clinical trials are required prior to regulatory approval, and usually take place in three phases. The first, usually involving a few dozen healthy volunteers, tests the vaccine for safety by monitoring for adverse effects. The second, involving several hundred people, usually in a part of the world, affected by the disease, looks at how effective the vaccine is, and the third does the same in several thousand people.
There is a high level of failure as experimental vaccines pass through these phases, and many are rejected. There are good reasons for that. Either the candidates are unsafe, or ineffective, or both. Screening is essential, which is why clinical trials cannot be easily accelerated.
Drugs for COVID-19
Antibiotics are not useful for treating a viral infection. Viral infections require either vaccinations to prevent them in the first place or antiviral drugs to inhibit their reproduction.
Two or more anti-virals are often used in a ‘cocktail’ to increase their effectiveness. Such combinations are used for HIV/AIDS, for example.
For COVID-19 infections, some known anti-virals are being tried. In China, lopinavir, and ritonavir were used during the SARS epidemic, and remdesivir, effective against Ebola, are being used for severe cases. Of the newer ones, favipiravir, under trial now in China, is showing promise.
Anti-virals are very expensive. The Indian pharma company, Cipla, made AIDS anti-viral treatment much more affordable, bring down prices from $8000 a year to $1 per day. This move angered the profit-gouging big pharma industry in the US, but was welcomed by health workers everywhere, especially in Africa.
So far, Cipla has developed over 15 single and combination medicines that has revolutionised HIV therapy across the world. Cipla has now come forward to immediately manufacture three promising chemical compounds with anti-viral properties for the treatment of Covid, with CSIR-Indian Institute of Chemical Technology.
It is not clear, however, what time period is meant by ‘immediately’.
Another strategy is to try already available drugs. The anti-malarial, chloroquine is being mentioned as a possible candidate since it has been shown to block corona virus replication in lab tests.
Chloroquine is also being used as a prophylactic. But unless proper human trials are undertaken, such ideas are only speculative. Doctors, who are in the front-line treating patients, have no definitive guidelines for duration of treatment, dosages, etc. Chloroquine is not approved for COVID-19 infections in the US, even if Trump says that he has given ‘permission’.
Another line of treatment is to use the plasma of infected patients. Plasma is golden-coloured fluid of blood that remains after the red cells are removed. You may have noticed this sometime, after a bleeding injury, when the blood has clotted, an oozing yellow, clear or translucent fluid around the wound.
Plasma contains antibodies, i.e, the protective molecule that the body’s immune system produces to combat (by binding with) the invasive virus or bacteria. These antibodies could give readymade protection to another person through an injection or IV infusion.
At present patients are only given supportive treatment in hospitals, and some patients with lung disease will require ventilators in an ICU. For those with mild disease and at home, paracetamol is adequate for fever. Ibuprofen is not recommended and may worsen he disease.