Of the 150-plus coronavirus vaccines in development around the world, the lion’s share will rely on a needle prick to make their way into the body, according to the New York Times.
The COVID-19 vaccines closest to the finish line are designed to be injected into the arm, twice for effectiveness, and scientists are hoping to generate superior immune responses with inhaled vaccines that directly target the airway cells the virus invades.
Yet more tried and still being tested ways exist to get the inoculation.
Inhaling the vaccine
Sprayed and inhaled immunizations are under development in the U.S., Britain, and Hong Kong aiming to prevent pathogens from growing in the nose, from where it can spread to the rest of the body, and other people.
Inhaled vaccine makers are counting on some of the unique features of the lungs, nose, and throat, which are lined with mucosa. This tissue contains high levels of immune proteins, called IgA, that give better protection against respiratory viruses.
Without a strong mucosal response, injected vaccines may be less likely to produce so-called sterilizing immunity, a phenomenon in which a pathogen is purged from the body before it’s able to infect cells. In that case, vaccinated people might be protected from severe disease, but could still be infected, experience mild symptoms, and occasionally pass small quantities of the germ onto others.
Vaccines that are sprayed into the nose or inhaled may hold other practical benefits. They are painless, don’t require needles, may not need to be stored and shipped at low temperatures and needle-phobic people need not worry.
Altimmune, Maryland, scientists at the University of Oxford working with AstraZeneca Plc pharma, Imperial College London, and researchers in Hong Kong are aiming for an intranasal vaccine with human tests starting next month that would simultaneously offer influenza and COVID-19 protection.
Other ways to inoculate
Vaccines are traditionally administered with a needle, but this isn’t the only way. Certain vaccines can be delivered orally, as a drop on the tongue, or via a jet-like device as used in dental care to deliver a local anesthetic.
Oral vaccines can come as a liquid or tablet.
More recently, researchers and biotechnology companies have developed skin patches but these are mostly still in clinical testing.
DNA vaccines, when injected into the muscle can generate an immune response.
With a DNA vaccine, a small section of the genetic material of the virus is delivered into cells under the skin. These cells then express the DNA as viral proteins. The body recognizes these as foreign and stimulates an immune response.
The needle-free methods include ultrasound (sound waves) and electroporation (electrical pulses) that disrupt cell membranes, allowing DNA into the cells.
Liquid jet injectors use small volumes of liquid forced through a tiny opening (smaller than a human hair). This ultra-fine high-pressure stream penetrates the skin where cells then take up the vaccine and stimulate immune cells.
Other needle-free COVID-19 vaccines in development include a band-aid-like patch made up of 400 tiny needles, a nasal vaccine, an oral vaccine as a tablet, and a needle-free device that delivers an mRNA vaccine.
Vaccines based on mRNA work in similar ways to DNA vaccines.
Administering is key
If you don’t administer the vaccine properly, at least with needles, you might as well not give it at all. One common mistake is that too short a needle is used: A subcutaneous “Subcut” needle rather than an intramuscular “IM” needle. When this happens, the vaccine can be injected into fat instead of into muscle.
And when spraying, half of the vaccine should be sprayed into each nostril and the patient should be seated in an upright position.
Who should get the vaccine first?
After health-care workers, medically vulnerable groups should be among the first to receive a vaccine, according to a play by the National Academies of Sciences, Engineering, and Medicine (NASEM). These include older people living in crowded settings, and individuals with multiple existing conditions, such as serious heart disease or diabetes.
The plan prioritizes workers in essential industries, such as public transit and people who live in certain crowded settings, like homeless shelters and prisons.