Will inhalation vaccine become the gospel of needle fainting people?

On November 2, the world’s first inhalable new crown vaccine was unveiled at the “2021 5th Hainan International Health Industry Expo”!

The atomized vaccine is inhaled into the human respiratory tract and lungs through the mouth, so as to stimulate mucosal immunity. At present, the project has achieved phased results in phase II clinical trial, and the application for emergency use is being urgently promoted.

This means that the new crown vaccine does not have to be injected intramuscularly! From the news pictures, the vaccine carrying model is like a cup of milk tea. I don’t know if it will be fruity? After all, the vaccine sugar pills we ate as children are sweet.

The operation of inhaled vaccine sounds convenient, but what is the principle? What is mucosal immunity? Since many people have received intramuscular injections, why develop inhalable vaccines? Will inhalation vaccine become the gospel of needle fainting people?

Changes in the mode of administration are important & nbsp& nbsp;

First of all, we must affirm the significance of the birth of inhaled vaccine, because the change in the administration mode of the new crown vaccine may be as important as the invention of the first new crown vaccine.

For example, in 1956, Jonas Salk won the famous Lasker Clinical Medicine Award.

The reason for winning the award is precisely because Salk invented the polio vaccine (the initial form of the “sugar pill” we ate when we were young to treat polio). As an honor second only to the Nobel Prize in medicine, the award of polio vaccine is likely to be the end of this disease in Lasker’s award-winning history.

Because it is hard to imagine any breakthrough in this field after the emergence of vaccines, which can win the favor of this award again, not to mention that in 1949, three scholars have won a Lasker Award for realizing the in vitro culture of poliovirus.

But nine years after the award of polio vaccine, polio vaccine won the Lasker Award again. Albert B。 Sabin, who invented the oral polio vaccine in 1965, once again won a Lasker trophy for the polio field.

Some people think that the intramuscular vaccine we use now is enough to fight against the new crown. However, the change in the mode of administration is still a blessing for all mankind. The best evidence is that the Lasker prize is awarded to injection poliomyelitis and oral poliomyelitis respectively.

Therefore, if someone thinks that academician Chen Wei’s inhaled vaccine is an insignificant innovation, it is too wrong.

Advantage 1: the gospel of needle syncope patients & nbsp& nbsp;

First, the intramuscular new crown vaccine is not applicable to everyone. In other words, if you can choose not to inject, many people will choose inhaled vaccine without hesitation. In China, where the whole people participate and support the fight against the epidemic, most people will receive intramuscular injection of the new crown vaccine whether they like injection or not.

However, in many countries such as the United States, needle phobia is not a small problem, which directly affects the vaccination rate.

A Meta-analysis study in 2018 shows that 20% – 50% of teenagers in the United States fear needles, and 20% – 30% of young adults fear needles.

Such a high proportion of needle fear leads to 8% – 27% of employees in the medical system and adult patients avoiding influenza vaccination. It may be incomprehensible for most people not to vaccinate because of fear of needles. However, in the United States, this is an important factor hindering the improvement of vaccination rate [1].

Inhalation vaccination is simpler and painless. It is an excellent supplement to intramuscular injection. It can effectively improve the vaccination rate in some countries and become a magic weapon to knock down the new crown. For areas where needle phobia is not a problem, inhaled new crown vaccine is also a good alternative.

    & nbsp; Advantage 2: easy storage & nbsp& nbsp;

Another major advantage of inhaled vaccine is that it can be prepared in the form of dry powder. Although the inhaled new crown vaccine of academician Chen Wei’s team is obtained by atomizing the original intramuscular injection with Ad5 ncov liquid, the vaccine with Ad5 carrier has also been proved to use freeze-drying process [2], and the dry powder and inhaled vaccine are better matched~

Now the inhaled Ad5 vaccine is available. In the next step, as long as it can be made into dry powder, it is possible to solve another major problem hindering the vaccination rate of the new crown vaccine – distribution. Cold chain is a difficult problem of intramuscular new crown vaccine. The advantages of inhalation type which can be prepared into dry powder in distribution are self-evident.

At present, the mainstream vaccines are basically transported at 2-8 degrees or even ultra-low temperature, while the traditional dry powder vaccines can be stored at room temperature for a long time. Higher stability means that the vaccine is easier to distribute to end users.

At the same time, compared with intramuscular injection, which requires certain skills and equipment (needles), inhalation vaccination is simpler, and even has the opportunity to be made into the form of mass simultaneous vaccination. These are advantages that intramuscular vaccination has never had.

    & nbsp; Advantage 3: stimulate immune response & nbsp& nbsp;

The new crown is a disease mainly caused by the host of respiratory tract infection. The virus does not puncture people with needles. The nasal microenvironment has been proved to be the most central role in the process of COVID-19 infecting the host [3].

The inhalation vaccine is very close to the infection form of the new crown itself, which means that it can stimulate a more realistic immune response to bring better protection.

Mucosal immunity is a very important form of immunity in the human body, but the traditional intramuscular injection naturally lacks this link because it does not pass through the mucosa of the respiratory system. Inhalable vaccines perfectly fill this gap.

The inhalation vaccine of academician Chen Wei’s team can better stimulate mucosal immunity and the production of secretory IgA (sIgA), which plays a major role in mucosal immunity, than the intramuscular vaccine.

Due to the difficulty of detection, although there is no SIgA data in the paper published by Chen Wei’s team in Lancet, the level of serotype IgA is still very high.

Theoretically, the level of SIgA induced by inhaled vaccine is also higher. The same neutralization antibody, the ability of IgA to neutralize COVID-19, is 7 times [4] of IgG immunity induced by most vaccines.

Needless to say, sIgA can kill COVID-19 directly in the nasal cavity where it can survive and proliferate and induce the next transmission. This means that inhaled vaccines are more protective. Even if the vaccine has a breakthrough infection due to mutation, its ability to spread again should be weaker.

At present, the protection induced by the existing intramuscular vaccine in the upper respiratory tract is relatively weak. Although the people infected with the new crown after vaccination will not have too serious symptoms, the virus can proliferate and spread in the nasal cavity without worry, and then infect others. After the mucosal immunity is strengthened by the inhalation vaccine, this loophole can be blocked, and finally the real mass immunity can be realized.

    & nbsp; Inhaled new crown vaccine or mainstream & nbsp& nbsp;

The research and development of inhalation vaccine may be a key link in our “war epidemic”. At present, other inhaled vaccines under development include delns1-2019-ncov-rbd-opt1 of Beijing Wantai and covi-vac of codagenix, all of which are undergoing clinical trials.

At present, AstraZeneca’s azd1222 adenovirus related vector vaccine is also trying to make an inhalation vaccine. In animal experiments, inhalation can significantly reduce the content of virus in nasal cavity compared with intramuscular injection [5]. However, there are too few data to support the conclusion of significance. Academician Chen Wei’s inhaled vaccine has only published phase 1 clinical results.

Professor Chen Wei’s team published the results of phase I clinical trial in Lancet sub journal

However, we sincerely hope that the advantages of inhaled vaccine can be realized one by one in later large-scale clinical trials. In the near future, we may really have a fruit flavored vaccine~

References:

  1。 McLenon, J。 and M.A.M。 Rogers, The fear of needles: A systematic review and meta-analysis。 J Adv Nurs, 2019。 75(1): p。 30-42。

  2。 Zhang, J。, et al。, An adenovirus-vectored nasal vaccine confers rapid and sustained protection against anthrax in a single-dose regimen。 Clinical and vaccine immunology : CVI, 2013。 20(1): p。 1-8。

  3。 Gallo, O。, et al。, The central role of the nasal microenvironment in the transmission, modulation, and clinical progression of SARS-CoV-2 infection。 Mucosal Immunology, 2021。 14(2): p。 305-316。

  4。 Wisnewski, A.V。, J。 Campillo Luna, and C.A。 Redlich, Human IgG and IgA responses to COVID-19 mRNA vaccines。 PLOS ONE, 2021。 16(6): p。 e0249499。

  5。 van Doremalen, N。, et al。, Intranasal ChAdOx1 nCoV-19/AZD1222 vaccination reduces viral shedding after SARS-CoV-2 D614G challenge in preclinical models。 Sci Transl Med, 2021。 13(607)。

Source: viax salt



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