A health worker wearing personal protective equipment (PPE) collects samples for public nasal congestion testing. Virus blocking is a simple premise based on blocking SARS-CoV-2. In other words, if something gets in its way, the virus cannot attach to the cell and infect you. For a representative image. | Photo Credit: Ramalingam Jothi B
We have vaccines that boost our immune response to SARS-CoV-2, the virus that causes Covid. We have medicines you can take at home (and in the hospital) to treat covid. Now researchers are trying something new.
First of all, they want to prepare drugs that stop the virus from entering the body. Nasal secretions stop the virus from attaching to cells in the nose.
Other researchers are looking at the potential of nasal sprays to stop the virus from replicating in the nose or to make the nose a hostile site for entry into the body.
Here’s where the science is and what we can expect next.
How can we stop the virus?
As the name suggests, “viral inhibition” is a simple precondition based on inhibiting SARS-CoV-2. In other words, if something gets in its way, the virus cannot attach to the cell and infect you.
As SARS-CoV-2 is a respiratory virus, it is appropriate to deliver this type of medicine where the virus primarily enters the body – nasal spray.
There are various groups around the world working on this concept. Some research is still going on in the lab. Some agents have advanced to preliminary human trials. None of them are yet in widespread use.
Heparin
Heparin is a common drug that has been used for decades to thin the blood. Studies in mice have shown that when heparin is given through the nose, it is safe and effective in preventing the virus from coming into contact with nasal cells. Researchers believe that heparin binds to the virus and stops it from attaching to the cells the virus is trying to infect.
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A clinical trial is being conducted in Victoria in collaboration with several Melbourne-based research centers and the University of Oxford.
Covixil-v
Covixyl-V (ethyl lauroyl arginine hydrochloride) is another nasal spray in development. It aims to prevent covid by blocking or modifying the cell surface to prevent the virus from infecting it.
This compound has been explored for use against a variety of viral infections, and preliminary studies in cells and small animals have shown that it inhibits SARS-CoV-2 attachment and reduces overall viral load.
Iota-carrageenan
This molecule from the seaweed works by preventing the virus from entering the air.
A study of nearly 400 healthcare workers found that nasal sprays could reduce the risk of contracting the virus by up to 80 percent.
IGM-6268
This is an engineered antibody that binds to SARS-CoV-2 and prevents the virus from attaching to cells in the nose.
Nasal and oral (oral) sprays are in clinical trials to assess safety.
Cold atmospheric plasma
This is a gas containing charged particles. Cold temperatures can alter the cell surface.
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Laboratory studies have shown that the receptors on the skin show gas changes that allow the virus to infect it. This results in less SARS-CoV-2 attachment and infection. Scientists now think this technology could be adapted to nasal sprays to prevent SARS-CoV-2 infection.
How can we stop the virus from replicating?
Another method is to prepare nasal drops that stop the virus from multiplying in the nose.
Researchers are designing genetic fragments that bind to viral RNA. These pieces – known as “locked nucleic acid antisense oligonucleotides” (or LNA ASOs for short) – put a proverbial spanner in the works and stop the virus from replicating.
These gene fragments, which are injected into the nose, reduce virus replication in the nose and prevent disease in small animals.
How can we change the nose?
A third strategy is to change the nasal environment to make it less hospitable to the virus.
This can be done by changing the humidity (with saline), changing the pH (making the nose more acidic or alkaline), or using a nasal spray with an anti-viral agent (iodine). Saline can reduce the amount of SARS-CoV-2 in the nose by simply washing away the virus. A study found that saline nasal irrigation may reduce the severity of Covid-19. But we need more research on saline sprays.
An Australian-led study found that iodine-based nasal sprays can reduce the viral load in the nose. Further clinical trials are planned.
One study used an experimental spray – containing ingredients such as eucalyptus and clove oils, potassium chloride and glycerol. The aim was to kill the virus and change the acidity of the nose to prevent the virus from spreading.
This novel formula has been shown to be safe in laboratory and clinical trials and has reduced the infection rate from 34 percent to 13 percent compared to the placebo control.
Obstacles ahead
Although the data so far on nasal sprays for Covid is promising, one of the main hurdles is keeping the sprays in the nose. To overcome this, most sprays require multiple applications per day, sometimes every few hours.
So, from what we know so far, nasal spray alone will not defeat covid. But if they’re shown to be safe and effective in clinical trials and get regulatory approval, they could be another tool to help prevent it.
By Lara Herrero, Researcher in Virology and Infectious Diseases, Griffith University (The Discussion)
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