In China- the first inhalable vaccine against Covid-19: Can needle-free work?

Subject: Science and Technology

Context-

Shanghai (China) authorities have started administering an inhalable vaccine (first in the world) against covid-19.
The vaccine is being offered for free as a booster dose for previously vaccinated people.

Administering process-

The vaccine is a mist that is sucked in through the mouth.
After slowly inhaling, people hold their breath for five seconds, with the entire procedure completed in 20 seconds.
It was like drinking a cup of milk tea.
The inhalable vaccine has been developed by the Chinese biopharmaceutical company CanSino Biologics Inc. as an aerosol version of its one-shot adenovirus vaccine, which uses a relatively harmless cold virus.

Intranasal vaccine-

In September this year, India’s national drug regulator cleared Hyderabad-based Bharat Biotech’s iNCOVACC, the country’s first intranasal Covid-19 vaccine for emergency use in unimmunised adults.
iNCOVACC, which uses a modified chimpanzee adenovirus, will be delivered through the nasal route, which would potentially trigger an immune response in the mucosal membrane. It has been designed to not only protect against infection but also reduce transmission of the virus.
The vaccine is not yet part of India’s national immunisation programme.
Bharat Biotech, the manufacturer of Covaxin, first announced an intranasal vaccine in September 2020, after the first wave of the pandemic.

Easy to deliver-

Any needle-free vaccine would be easy to administer, and would cut down on the dependence on trained personnel, ultimately making mass immunisation more accessible in poorer countries and countries with inadequate healthcare infrastructure.
Also, experts have pointed out that needle-free shots might persuade those who do not like to be injected to get the vaccine.
Zydus Cadila’sZyCoV-D, the first Covid-19 vaccine built on a DNA platform, is an intradermal vaccine that is applied through the skin, but using a needle-free system.

Questions remain-

While around a dozen nasal vaccines are being tested globally according to the World Health Organization, the effectiveness of non-needle vaccines is yet to be fully tested.
Save for some flu vaccines, this route of delivery has not been very successful so far.

Types of vaccines-

Inactivated vaccines:

Inactivated vaccines use the killed version of the germ that causes a disease.
Vaccines of this type are created by inactivating a pathogen, typically using heat or chemicals such as formaldehyde or formalin. This destroys the pathogen’s ability to replicate, but keeps it “intact” so that the immune system can still recognize it. (“Inactivated” is generally used rather than “killed” to refer to viral vaccines of this type, as viruses are generally not considered to be alive.)
They usually don’t provide immunity (protection) that’s as strong as live vaccines. So you may need several doses over time (booster shots) in order to get ongoing immunity against diseases.
They are Used to protect: Hepatitis A, Flu (shot only), Polio (shot only), Rabies.

Live-attenuated Vaccines:

Live vaccines use a weakened (or attenuated) form of the germ that causes a disease.
Because these vaccines are so similar to the natural infection that they help prevent, they create a strong and long-lasting immune response.
The limitation of this approach is that these vaccines usually cannot be given to people with weakened immune systems.
Live vaccines are used against: Measles, Mumps, Rubella (MMR combined vaccine), Rotavirus, Smallpox among others.

Messenger (m) RNA Vaccines:

mRNA vaccines make proteins in order to trigger an immune response. mRNA vaccines have several benefits compared to other types of vaccines, including shorter manufacturing times and, because they do not contain a live virus, no risk of causing disease in the person getting vaccinated.
The vaccines are used to protect against: Covid-19.

Subunit, Recombinant, Polysaccharide, and Conjugate Vaccines:

They use specific pieces of the germ – like its protein, sugar, or capsid (a casing around the germ). They give a very strong immune response.
They can also be used on people with weakened immune systems and long-term health problems.
These vaccines are used to protect against: Hib (Haemophilus influenzae type b) disease, Hepatitis B, HPV (Human papillomavirus), Pneumococcal disease among others.

Toxoid Vaccines:

They use a toxin (harmful product) made by the germ that causes a disease. They create immunity to the parts of the germ that cause a disease instead of the germ itself. That means the immune response is targeted to the toxin instead of the whole germ.
Toxoid vaccines are used to protect against: Diphtheria, Tetanus.

Viral Vector Vaccines:

Viral vector vaccines use a modified version of a different virus as a vector to deliver protection.
Several different viruses have been used as vectors, including influenza, vesicular stomatitis virus (VSV), measles virus, and adenovirus, which causes the common cold.
Adenovirus is one of the viral vectors used in some Covid-19 vaccines being studied in clinical trials.
The vaccines are used to protect against:Covid-19.