• William Miller, MD

Monoclonal Antibody Treatment for COVID

Antibodies are proteins made by our immune system that stick to invading bacteria or viruses. In doing so, they assist the immune cells in quickly identifying and clearing infection. Antibodies are normally made only after the immune system has seen the infection for the first time and as a result are the “memory” that gives us “immunity”. In other words, we do not have antibodies against an invader the first time we encounter the infection. All vaccines work by stimulating the immune system to create antibodies against an infection and thus have the “memory” without the person having to get the actual infection.

For a long time, we have known that we can give someone an injection of antibodies that will give temporary immunity as long as those antibodies stay in circulation, which is usually about 12 weeks. For example, we gave travelers gamma globulin shots before they went on trips to places were hepatitis was prevalent. Gamma globulin was simply pooled antibodies from many blood donors and contained antibodies against many things, including hepatitis. Now we simply vaccinate them against hepatitis, which is better because it gives lasting immunity instead of a temporary one.

Early in the COVID pandemic, we experimented with giving patients “convalescent serum”. This was simply serum from a COVID patient who got sick and survived. This was done because that serum contained the donor’s antibodies against the infection. Subsequently, the specific antibodies that were most effective were identified and then manufactured artificially in a lab. This is what is meant by “monoclonal antibody”. There are several monoclonal antibody preparations available for COVID, but the most effective so far is Regen-COV.

Regen-COV is made by Regeneron and is a combination of two artificially manufactured antibodies against SARS-2, the virus that causes COVID. It has shown effectiveness against most of the strains including the Delta variant. In selected patients, it can reduce the risk of progression of illness and hospitalization by about 50%. It may also reduce fatality by an equal amount in certain patients.

Before we go further, recall some important statistics about COVID. First, the majority of persons, 70% or so, who get infected with SARS-2 either never develop symptoms or their symptoms are mild. Of the remaining 30% who do develop more significant symptoms, about a third (12% of the total) require hospitalization. Only about 4-6 % of all persons with COVID get so sick as to be an ICU. The overall fatality rate in the US is about 2%. The Delta variant approximately doubles some of these figures with about half of infected persons becoming symptomatic and around 24% ending up in a hospital.

The FDA granted Emergency Use Authorization (EUA) for giving Regen-COV to selected patients back in April. The recipient has to be positive for COVID with only mild to moderate symptoms, and in a group that is high-risk for progression to more serious illness. The treatment must be given within ten days of onset of symptoms and preferably within the first five days for greatest effect. The treatment only helps to prevent progression from mild/moderate to more severe. If symptoms are already severe, such as the patient is in a hospital already, then there is no benefit from the treatment.

Like most things related to this pandemic, Regen-COV was hard to get initially back in April when it first received EUA approval. However, now it is more readily available and we are giving it to patients here on the Coast at Adventist Health (AH) Mendocino Coast hospital and inland through AH Ukiah Valley hospital. The intravenous (IV) infusion takes a little over 30 minutes and there is a 1 hour observation that follows. As with other antibody infusions, the biggest risk is anaphylaxis which occurs rarely (less than 1% of the time). We are not giving it as a subcutaneous injection as it is slightly more effective if given IV. The FDA also added the possibility for use as post-exposure prophylaxis, but that is limited only to people and settings of particularly high risk, such as during an outbreak in a nursing home. Wearing a mask remains your best defense against exposure in the first place.

The treatment requires an order from a doctor or other healthcare provider. If you have recently tested positive for COVID, are within ten days of onset of mild or moderate symptoms and feel that you may be a candidate to receive the infusion, then contact your primary care provider and discuss it. If you do qualify, then your provider will order it. Please, do not call the hospital or show up in the ER as a means of trying to get the treatment. Start with your primary care provider who would be the one to order it for you.

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