UncategorizedPosted on Monday, August 6th, 2012 - 6:58 am
Seminars in Genomic Medicine
COVID-19 (SARS-CoV2): FEW FACTS AND NEW DEVELOPMENTS
The Covid-19 virus belongs to the Corona virus family. Other members of this family include severe respiratory distress syndrome (SARS) and the middle east respiratory syndrome (MERS), previously involved for two major endemics, but NOT at the epidemic or pandemic scale. All these viruses occur naturally in wet-animals (reptiles, amphibians & variety of seafood). All Corona viruses have special affinity for respiratory epithelium.
Animals, mostly mammals (Bats & Humans), who consume these wet animals, could acquire the Corona virus. Infected Bats and Humans develop respiratory illness that could progress to severe respiratory distress with high risk of dying. The lung changes range from widespread bronchiolar and alveolar inflammation leading to pulmonary fibrosis. Survivors of this infection could become chronically oxygen dependent.
One of the key factors in tackling the spread of COVID-19 across the globe is testing. In South Korea, for example, mass testing has been used to try and quickly identify and isolate those with the disease. Testing is also vital to calculate accurate infection and survival rates – data that is critical for getting public safety measures right. And as this coronavirus continues to spread, people are being offered tests for sale, either at a high price from private clinics, or tests that are not officially approved, or perhaps even fake. So what tests are being used by health officials, how much do they really cost and what developments are there to come?
Two types of currently available tests for SARS-CoV2, the coronavirus that causes COVID-19 disease and the cause of 2020 pandemic.
- The first testing method is a very sensitive test that looks for the RNA of the virus using a technique called RT-PCR (reverse transcriptase polymerase chain reaction). This can detect as little as one virus particle in swabs taken from inside the mouth or nose.
- The second type of test measures the antibody responses to the virus in blood serum, similar to many other blood antibody tests for many other viral infections. There are
many virus components that our bodies make many different antibodies against.
Development of antibody against any infection can either destroy the virus or stop the infection. A positive Covid-19 antibody test would simply mean exposure to SARS-CoV2 including other Corona family viruses. In other words it is NOT 100% specific; however, important for risk categorisation of people, particularly the front line Doctors, Nurses, key workers and carers.
The antibody test itself is very simple and cheap. The test requires purified virus components in a test tube to which a very diluted blood sample from the patient is added and let any antibodies bind to the test tube. Antibody typically takes a few weeks to develop against a new infection and lasts much longer in the bloodstream than the virus itself. The COVID-19 “serology” testing is a powerful tool to check if people have encountered the infection and as well as to assess the efficacy of vaccines. Rapid progress in being made for developing the vaccine against the SARS-CoV2 (Covid-19) strain. It is important to note that the current antibody tests for the novel coronavirus are yet to be validated for mass use, which is why WHO guidelines recommend RT-PCR testing. Prof. Chris Whitty, the UK Chief Medical Officer, said that a test that could reliably detect past infection would be “transformational”. The government recently announced that it had ordered 3.5 million home tests that could soon become available for NHS workers and some members of the public via Amazon once they were validated.
Most countries rely on RT-PCR method, as it is highly specific (low false positive cases) and very sensitive (low false negative cases). One of the Indian Genomic Laboratories has developed a kit using this method; others are fast developing. Most such tests will cost less than Rs. 2000 (just under £25). In the UK, the RT-PCR test remains the primary method, using a network of labs doing the same standardized test. Private labs in the UK are charging up to £375 for this test.
So far WHO or any other large Global agency, like Bill Gates Foundation, have not come forward to finance this test for poor or middle income countries. Most countries currently employ this test for identification and isolation of infected people, consistency in data collection and comparing useful statistics on the infection rate and outcomes.
There is no specific Covid-19 anti-viral therapy available yet. Claims made in India and other places on the therapeutic potential of combined chloroquine and anti-retroviral drugs should NOT BE TAKEN seriously. There is no evidence based on either double randomised trial or selected case-controlled study. It is anecdotal and unscientific. Surprisingly Indian Council of Medical Research (ICMR) has approved chloroquine for Covid-19, particularly in high-risk people and health workers.
In the USA, despite lots of hype for hydroxychloroquine (Plaquenil), the Food and Drug Administration is still undecided. WHO has yet to approve its use for treating the Covid-19 virus. Other countries have started case-based emergency clinical trials. The US President, Donald Trump, believes that it should be given ‘a try’! The chloroquine, a derivate of quinine, is very potent anti-malarial drug with anti-inflammatory qualities. Historically, it used to be good anti-inflammatory drug prior to the discovery of non-steroidal antiinflammatory drugs (Brufen, Naproxyn, Voltarol etc.). Doctors should not prescribe as chloroquine or hydroxychloroquine are very toxic with serious side effects. As the drug is cheap and widely available on the counter, risks of self-prescribing are very high.
Inevitably, many Doctors, Vaids and Hakims across India have claimed on the efficacy of several indigenous animal (Cow urine) and herbal medicine (usual combination of Ayurvedic products). Perhaps claims on beneficial effect of physical, behavioural and life-style modifications are justified and need to be explored, but on your own, as traditional group or community approach might be counterproductive due to risks of cross infection.
It is likely that some of the above contents might change as we come across and digest more information. However, the fact remains that Covid-19 (SARS-CoV2) is highly contagious spread by droplet aerosols and contact, however trivial that might be.
The key to prevention is isolation, social distancing, protection (self and others) by frequent hand washing or liberal use of alcohol gel and probably the use of facemasks.
Compiled by Professor Dhavendra Kumar, Cardiff / London, 29 March 2020