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What is the evidence for COVID 19 treatment before monoclonal antibody cocktail therapy?
At the beginning of the pandemic, no evidence-based treatments were available for COVID19, several treatment options were investigated including antivirals (e.g., Remdesivir and favipiravir and lopinavir/ritonavir), antibiotics like azithromycin and doxycycline, and anti-parasitic drugs (e.g., ivermectin) with limited clinical efficacy.
Convalescent plasma therapy showed initial promise in the treatment of COVID-19 patients, but later clinical trial data have shown no benefit, likely due to variation in the active concentration of neutralizing antibodies and subsequent lack of standardized doses and selection of sick patients.
Corticosteroids and tocilizumab and Baricitinib have shown mortality benefits in sicker patients, however, there is a role of these drugs in the early stage of the disease to prevent progression.
How does this monoclonal antibody cocktail therapy emerge?
SARS-CoV-2 enters host cells through interactions between the viral spike protein and the cellular angiotensin-converting enzyme 2 (ACE2) receptor. The spike protein is, therefore, a rational target for leading COVID-19 vaccines and neutralizing antibody-based therapies.
Casirivimab and Imdevimab, developed by Regeneron, bind non-overlapping epitopes of the Receptor binding domain(RBD), and helps in reducing viral load by preventing virus entry into cells, investigated as a cocktail in the ambulatory setting, The trial met its primary endpoint and revealed that the Casirivimab and Imdevimab cocktail significantly reduced the risk of hospitalization or death by 70%.
All key secondary endpoints were also met, including a four-day reduction in the median duration of symptoms.
Who should take this?
Approved for non-hospitalized COVID-19 patients with mild to moderate illness who have certain risk factors for severe disease
- Older age (≥65 years)
- Body mass index (BMI) ≥25 kg/m²
- Pregnancy
- Chronic kidney disease
- Diabetes mellitus
- Immunosuppression (immunosuppressive disease or treatment)
- Cardiovascular disease (including congenital heart disease) or hypertension
- Chronic lung disease
- Sickle cell disease
- Neurodevelopmental disorders (eg, cerebral palsy) or other medically complex conditions (eg, genetic or metabolic syndromes and severe congenital anomalies)
What is our experience with new therapy so far?
We had 321 patients who have taken antibody cocktail after they have tested positive for COVID 19 on RT PCR, among them 297 patients were administered on a daycare admission basis for one hour of observation for adverse reactions and discharged and 23 patients were admitted to the hospital for observation and discharged later.
245/321(78%) patients were high risk elderly with comorbidities and 76/321(22%) were young adults who had a high risk for clinical progression.
All the patients who have taken antibody cocktail on a daycare basis were followed up for a period of three weeks either by physically or teleconsultation.
2 of 297(0.6%) patients were admitted to the hospital with worsening symptoms and they were treated with a standard protocol (Remdesivir dexamethasone, enoxaparin) and they were discharged in 7 days and there is no mortality seen among all the patients who have taken a cocktail.
How is the patient’s feedback?
The majority of patients had great symptomatic relief after 24 hr to 48 hrs post antibody cocktail, however, few patients had a generalized weakness for a week.
Does it require for people even after two doses of vaccination?
We have few interesting observations in our data, we did a sero-surveillance for COVID antibodies of 157 patients before giving cocktail therapy, 17 patients out of these 157 were not vaccinated and among who had been vaccinated 118/140(85%) are seronegative for antibodies and only 22(15%) had seropositivity.
We also checked data of COVID admissions for moderate or severe disease in the last two months, the majority of them were vaccinated with two doses of COVAXIN or COVISHIELD who were treated with Remdesivir, corticosteroids, anticoagulants.
Hence it is advisable to take antibody cocktails irrespective of their vaccination status if they fall into a high-risk group.
Are there any side effects of the drug?
All the patients were administered 600mg+600mg of Casirivimab and Imdevimab through intravenous infusion in 100ml normal saline 0.9% over a period of 30 minutes and observation for one hour for adverse reactions, there were no transfusion reactions or serious adverse reactions seen in our patient group.
Do you think this newer therapy will be game-changer?
In our experience, we had a tremendously positive response for this newer antibody cocktail therapy in terms of a decrease in hospital admission (0.6%) and zero death rate by decreasing the viral load and thereby disease progression.
It is advisable to suggest antibody cocktail therapy for those high-risk patients by clinician irrespective of their vaccination status as poor seroconversion even after two doses in the real-world scenario as shown in our study.
It is also suggestible to patients even for younger patients who are at risk of worsening as it was witnessed during the second wave with delta variant.
New variants with resistance to monoclonal antibody cocktail might emerge in the future hence it is important to follow the patient till 21 days for assessing for well being of a patient.
Consultant - Interventional Pulmonologist
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