Updated: June 4, 2021 8:00:27 am
Since the emergence of Covid-19, multiple treatment strategies and protocols are being used to curb the prevalence of the virus, including neutralizing monoclonal antibodies cocktail drug, casrivimab and imdevimab. These antibodies are being developed in laboratories using specialised techniques to neutralise the SARS CoV-2 virus.
The Indian regulatory body CDSCO approved the use of these antibodies cocktail drugs (Casirivimab and Imdevimab) for limited emergency use, to treat mild to moderate Covid-19 in adults and paediatric patients (12 years of age and older weighing at least 40 kg) with laboratory confirmed SARS-CoV-2 infection and those who are at high risk of progression to severe Covid-19 and do not require oxygen. The antibodies cocktail drug is recommended to be given at early stages of laboratory confirmed SARS-CoV-2 infection, preferably within 10 days of the onset of symptoms.
Dr D Behera, Padma Awardee, and former Professor and HOD, Department of Pulmonary Medicine, WHO Collaborating Centre for Research and Capacity Building in Chronic Respiratory Diseases, explains some important questions pertaining to this new treatment strategy.
What have been the learnings in treatment protocols in this time of crisis. What has worked, and what was discarded?
The most common symptoms of Covid-19 are fever, tiredness and dry cough. Some patients may have aches and pains, nasal congestion, runny nose, sore throat or diarrhea. These symptoms are usually mild and begin gradually, whereas some people do not develop any symptoms. The other symptoms of Covid-19 may be fever or chills, cough, shortness of breath or difficulty breathing, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or runny nose, nausea or vomiting, diarrhea. Symptoms may differ with severity of disease. For example, shortness of breath is more commonly reported among people who are hospitalised with Covid-19 than among people with milder disease (non-hospitalised patients). Atypical presentations of Covid-19 occur often, and older adults and people with medical comorbidities may experience fever and respiratory symptoms later during the course of illness than people who are younger or who do not have comorbidities. In one study of 1,099 hospitalised patients, fever was present in only 44 per cent at hospital admission, but eventually 89 per cent of patients had a fever sometime during hospitalisation. Fatigue, headache, and muscle aches (myalgia) are among the most commonly reported symptoms in people who are not hospitalised, and sore throat and nasal congestion or runny nose (rhinorrhea) also may be prominent symptoms. Many people with Covid-19 experience gastrointestinal symptoms such as nausea, vomiting or diarrhea, sometimes prior to developing fever and lower respiratory tract signs and symptoms. Loss of smell (anosmia) or taste (ageusia) has been commonly reported, in a third of patients in one study, especially among women and younger or middle-aged patients. Some of the patients who get Covid-19 become seriously ill and develop difficulty in breathing. Older people, and those with underlying medical problems like high blood pressure, heart problems or diabetes, are more likely to develop serious illness. Depending upon the presence or absence of pneumonia and oxygen saturation levels the disease is classified into different categories like mild, moderate, severe and critical.
What is an antibody cocktail drug? What does it comprise? Have we ever used such a drug for other diseases?
Casirivimab and Imdevimab bind simultaneously to different, non-overlapping epitopes on the SARS-CoV-2 spike (S) glycoprotein and prevent its attachment to the ACE-2 receptors, thereby, blocking viral entry into the cells. Viral/antibody complex is then cleared by the immune system. In a clinical trial of patients with Covid-19, with mild to moderate symptoms and at high risk of progression to severe disease, compared with placebo, a single IV infusion of the combined regimen (1.2 g of Casirivimab and Imdevimab) reduced the risk of hospitalisation or death by 70 per cent. Data also suggests that the susceptibility to the combination antibodies was maintained even against the variant strains of concerns such as UK origin, South Africa origin, Brazil origin, New York origin and California origin. The mutations in some of these variants are also found in Indian double mutant variants. In the current Covid-19 surge, there are constraints of resources, the use of these monoclonal antibodies in right patients at the right time may benefit individuals by halting progression to severe disease.
Are more such drugs the need of the hour?
The treatment recommendations are guided by suggestions from various government and professional authorities depending on the severity of the patient. For those who are severely ill, optimal supportive care, including oxygen and other respiratory support may be required. Therapeutics depend on the stage of Covid-19 illness and risk factors. Some medications are recommended early in the disease course, while others are recommended during severe or critical illness with or without the use of oxygen supplementation. Many of the molecules such as Favipiravir, Remdesivir, neutralizing antibodies such as Casirivimab/Imdevimab have got restricted emergency use authorisation from the regulatory agency of India. Other drugs which are being used are steroids and immune modulators. There are many drugs which are currently being investigated for use in treating Covid-19.
Who will benefit from Covid-19 antibody drug cocktail?
Casirivimab and Imdevimab should not be used in patients who:
- Are hospitalized due to Covid-19, OR
- Require oxygen therapy due to Covid-19, OR Require an increase in baseline oxygen flow rate due to Covid-19 in those on chronic oxygen therapy due to underlying non-Covid-19 related co-morbidity
- Age =60 years
- Cardiovascular disease, including hypertension
- Chronic lung disease, including asthma
- Type 1 or Type 2 diabetes mellitus
- Chronic kidney disease, including those on dialysis
- Chronic liver disease
- Immunosuppressed, based on the investigator’s assessment. For example: cancer treatment, bone marrow or organ transplantation, immune deficiencies, HIV (if poorly controlled or evidence of AIDS), sickle cell anemia, thalassemia, and prolonged use of immune weakening medications.
When should the antibody drug cocktail treatment be used?
Clinical data suggests that the treatment will be beneficial to patients with mild to moderate disease, who are at risk of progression to severe disease, as it reduces the risk of hospitalisation and mortality. It is important that it should be given in early symptomatic phase within 10 days of the onset of symptoms. In the current Covid-19 surge, there are constraints of resources, the use of these monoclonal antibodies in the right patients at the right time may not only benefit individuals by halting progression to severe disease, but may also reduce the burden on the healthcare sector.
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