New vaccination technologies

Syringes and needles have been the primary method of vaccination for the past century. However, in the past few years, alternative routes of vaccine administration have emerged. Research groups and startups around the world are testing innovative solutions such as patches, sprays, tablets, dry powders, and even electrical impulses. The search for alternative approaches is driven by the need to address a number of challenges, including logistical difficulties, fear of injections, and the need to improve the effectiveness of protection, according to Gavi, an organization that helps poor countries gain access to vaccines. 

Let's take a quick look at the following innovative solutions: 

1. Microneedle patches

This patch contains hundreds of tiny needles. They painlessly penetrate the skin and deliver the drug to the epidermis and dermis, where immune cells are abundant. The drug is applied directly to the needles or incorporated into the patch itself. This patch is more convenient than traditional vaccines. It is lighter, more compact, and temperature-resistant, and can be applied without the help of a specialist.

A patch-based vaccine is currently being developed for 11 infections approved by the Vaccine Innovation Priority Strategy (VIPS) Alliance. 

2. Nasal Vaccines

These are vaccines administered via nasal sprays and inhalations. Their purpose is to induce protective immunity directly in the mucous membranes of the nose, throat, and respiratory tract, as these areas are the body's first line of defense against viruses such as influenza, coronaviruses, and RSV (respiratory syncytial virus).

These medications are designed to activate the production of immunoglobulin A (IgA) and T cells in the mucous membranes to stop the virus before it enters the cells, unlike traditional injections, which trigger a general immune response in the blood. 

3. Oral Vaccines and Edible Plants

Oral vaccines have a long history. Since the 1960s, an oral polio vaccine has been available, immunizing billions of children. Similar vaccines for cholera, rotavirus, and typhoid fever have since been developed. These vaccines act on the intestinal mucosa, where a local and systemic immune response is elicited. 

A new approach is edible vaccines. Scientists are genetically modifying plants (such as tomatoes and rice) to produce antigens that stimulate the immune system. Immunization occurs when these plants are consumed. However, a drawback of these vaccines is that the substances are destroyed by enzymes and acid before reaching the intestine.

Furthermore, capsules that will dissolve only in the small intestine are being developed. 

4. Needle-free injectors

Needle-free injections: a high-speed, pressurized jet of liquid delivers the vaccine to the targeted layers of skin or muscle.

The main obstacles in developing vaccines using this method of administration are antigen instability (especially in protein and mRNA vaccines) and the difficulty of adjusting the injection dose. To address the first issue, manufacturers are working to increase antigen stability and lyophilize them. The second issue is being addressed with "smart" injectors, which adjust the jet speed based on tissue resistance, minimizing pain and ensuring precise drug delivery. 

5. Electroporation

This method is an improvement over traditional injections. After the vaccine is administered, a special electrode is applied to the skin. It generates electrical impulses that open the "doors" in cells, thereby ensuring deeper and more effective penetration of the vaccine.

Electroporation improves the delivery of DNA vaccines, but it requires equipment and specialists, making it difficult to use in large-scale immunization campaigns. 

6. Dry Vaccines

This technology is applicable to all of the above-mentioned forms. Currently, the only truly popular lyophilized vaccine is the yellow fever vaccine, which has been used for decades.

Damage to the active ingredients during drying is difficult to avoid, especially with mRNA vaccines. These vaccines use a system based on sugars, polymers, and nanoparticles that maintains the integrity of the molecules during storage, enabling mass immunization without the need for a costly cold chain.