Dr Dharmakanta Kumbhakar
"Though vaccination against Covid-19 is going on all over the world including India, the people shouldn’t drop their safety guards. ...The use of mask and hand sanitizers, frequent hand washing with soap, maintaining respiratory hygiene and physical distancing should be followed strictly."
The whole world fought a battle against Covid-19 in 2020. The world had no idea how to respond to an unknown deadly novel coronavirus. Neither a vaccine to prevent the SARS-CoV-2 infection nor an effective drug to cure Covid-19 patients was available. Antipyretics, cough syrups and high flow oxygen therapy were only choices for symptomatic treatment. Due to lack of effective drugs to cure Covid-19 patients, a large number of Covid-19 patients lost their lives per day globally. This led to worldwide research about newer drugs to treat Covid-19 patients during the pandemic.
In the initial period of the pandemic, there was a lot of confusion regarding use of drugs like hydroxychloroquine, doxycycline, azithromycin and ivermectin for treatment of Covid-19 patients. The drug hydroxychloroquine was in the news for many weeks for its possible use in curing Covid-19. The US Food and Drugs Administration (FDA) identified the drug hydroxychloroquine as a possible treatment of Covid-19 and tested it on more than 1,500 Covid-19 patients in New Work. Anticipating that the drug hydroxychloroquine would work in the treatment of Covid-19, given the initial results, the then US President Donald Trump bought more than 29 million doses of hydroxychloroquine calling it as a ‘game changer’ for potential treatment of Covid-19. The US FDA even gave emergency use authorization to hydroxychloroquine to treat adult and adolescent Covid-19 patients who cannot participate in a clinical trial. Many US hospitals used hydroxychloroquine as the first-line therapy for hospitalized Covid-19 patients despite extremely limited clinical data supporting its effectiveness. The Brazilian President Jair Balsonaro even compared hydroxychloroquine to ‘Jeevan Dayini’ for the Covid-19 patients. Hydroxychloroquine is an inexpensive antimalarial drug similar to chloroquine, one of the oldest and best known antimalarial drugs with lesser side-effects. Various studies claimed that hydroxychloroquine demonstrates antiviral activity and has an ability to reduce the immune system’s response (as hydroxychloroquine acts as an interferon blocker) and hence may be useful in the treatment of Covid-19.
Moreover, the drug hydroxychloroquine shot to fame as it showed to have shortened the time to clinical recovery of Covid-19 patients. Few studies even claimed that hydroxychloroquine alone or in combination with antibiotic azithromycin appeared to reduce the viral load quicker and, hence, can reduce the duration and severity in Covid-19 illness. Gradually a clear picture emerged regarding the pathophysiology of the Covid-19 disease process and these drugs were no longer accepted in the treatment module of Covid-19. Moreover, few Covid-19 patients on hydroxychloroquine with azithromycin developed lethal cardiac side-effects.
The role of steroids to stabilize the excessive immune response as evidenced by the rise of IL-6 was widely discussed and was accepted as a part of standard regime for the treatment of Covid-19 patients. Moreover, the role of low molecular weight heparin to combat intravascular coagulation was established and it was also accepted as a part of standard regime for the treatment Covid-19 patients. Antiviral like Remdesivir was routinely used in many centres for treating Covid-19 patients. Few centres even used antiviral Lopinavir, Ritonavir and HIV Protease inhibitor for treatment of Covid-19. Monoclonal antibody like Tocilizumab was administered to Covid-19 patients with good results to combat cytokine storm. But, the drugs Remdesivir, Lopinavir, Ritonavir and Tocilizumab are too costly. Of course, high flow oxygen therapy essentially remained the primary treatment for Covid-19 patients once the oxygen saturation started falling.
The latest addition in the treatment of Covid-19 was convalescent plasma therapy (CPT). The US FDA authorized CPT for people with Covid-19 during the pandemic as there was no approved treatment for Covid-19. India’s Central Drugs Standard Control Organization (CDSCO) and the Indian Council of Medical Research (ICMR) permitted CPT or convalescent plasma therapy for the treatment of Covid-19. This therapy is a strategy for passive immunization which uses the plasma from people who’ve recently recovered from a viral illness to help others recover from the same viral illness. The concept of CPT is not a newer one. It is one of the century old treatment modality. This has been shown to be effective against the Spanish flu, which struck the world as a pandemic in 1918. In 1934, convalescent plasma was used for treating measles. More recently, the WHO approved convalescent plasma as empiric treatment against the Ebola virus infection in 2015, and it was deployed with success against the SARS and MERS coronaviruses as well (whose outbreaks occurred in 2002-2003 and 2012 respectively).
Convalescent plasma for Covid-19 refers to plasma obtained from an individual who has recuperated from SARS-CoV-2 infection. During the infection period, the individual’s immune system would have mounted an attack on the foreign SARS-CoV-2. By the time the virus is vanquished, the body of the Covid-19 individual would have developed ammunition specially to beat the virus, which will be a type of antibody.
These antibodies are suspended in the circulating plasma of the recovered Covid-19 individual. The plasma containing these antibodies called convalescent plasma is separated by an automatic aphaeresis machine. The collected convalescent plasma containing these antibodies can be administered to people with Covid-19 to boost their ability to fight the virus (passive immunization). This is the basic principle of CPT in the treatment of Covid-19 which can reduce mortality in Covid-19 patients by increasing neutralizing antibodies, clearing viruses and reducing clinical symptoms.
In theory, convalescent plasma is likely to be more effective in the early stages of SARS-CoV-2 infection, when the viral load is lower, and the Covid-19 patient can be saved from more severe stages. Convalescent plasma can be used as prophylactic treatment for Covid-19 also. However, few studies want to say that CPT has no role in critically ill Covid-19 patients. Hence, more research is necessary to establish the role of CPT in the treatment of severe Covid-19 cases.
In the absence of an effective and specific antiviral therapy for Covid-19, everyone worldwide was waiting for an effective vaccine since the beginning of the pandemic. Several pieces of research and clinical trials were on the run in various research centres worldwide for an effective Covid-19 vaccine during the pandemic. As on today, several Covid-19 vaccines are developed worldwide (e.g. Pfizer-BioNTech, Moderna, Oxford-AstraZeneca, Bharat Biotech, Janssen, Novavax, etc.) and most of the countries have started Covid-19 vaccination drives. All the Covid-19 vaccines show an acceptable safety profile, increased antibody response, and T-cell immune response against SARS-CoV-2.
The pandemic is not yet over. Majority of the European countries are still getting severely affected. Maharashtra, Kerala and Punjab are continuing to be the worst-hit States in India till date. Moreover, confirmed cases of infection caused by the new Covid strain, first detected in the UK, which is more contagious and severely infectious than the previous one, is also increasing in India.
Though vaccination against Covid-19 is going on all over the world including India, the people shouldn’t drop their safety guards. Until an effective medicine develops for the treatment of Covid-19 and complete coverage of population by vaccination, the use of mask and hand sanitizers, frequent hand washing, maintaining respiratory hygiene and physical distancing should be followed strictly.