New crown vaccine review, how effective are the 5 major vaccines?

According to Chen Erzhen, a medical expert in Shanghai, the scale of the epidemic in Shanghai this time exceeded the scale of the outbreak in Wuhan that year.

Recently, the main strains circulating in China have transitioned from the Delta strain to the Omicron BA.

The main strains circulating in China have transitioned from the Delta strain to the Omicron BA.

Structural biology expert Wang Nianshuang said that viruses should continue to evolve

BA.

Figure 1 shows the time and country when the main new coronavirus mutant strains were first reported, from "2021 New Coronary Virus Mutation, Cross-species Transmission, and a Review of Hot Spots in Vaccine and Drug Research"

About the new crown vaccine

About the new crown vaccine

On December 2, 2020, the world's first mRNA vaccine BNT162b2 received emergency use authorization in the UK

Figure 2 shows the timeline of the first approval of some new crown vaccines in the world, from "New Coronavirus Variants and Vaccine Research Status"

At present, the vaccination of the new crown vaccine is the best way to prevent SARS-Cov-2 infection.

The existing types of new crown vaccines include inactivated vaccines, live attenuated vaccines, recombinant protein vaccines, vector vaccines and nucleic acid vaccines

Figure 3 shows the types of new crown vaccine candidates, from "New Coronavirus Variants and Vaccine Research Status"

1.

Inactivated vaccine (inactivated virus vaccine) is a vaccine made by culturing the SARS-Cov-2 strain and inactivating it by physical and chemical methods

China's research on inactivated vaccines against the new coronavirus is relatively early.

1.

Live-Attenuated Vaccines are genetically modified or chemically treated live viruses to obtain attenuated or avirulent pathogen variants, which are inoculated into humans and still have antiviral properties similar to naturally infected viruses.

The live attenuated vaccines currently in phase I clinical trials are COVI-VAC and MV-014-212, which were developed by the Serum Institute of India in cooperation with Codagenix, and by Meissa Vaccines in the United States.

1.

Recombinant protein vaccine (recombinant protein vaccine) is to construct the desired target gene on an expression vector.

Existing recombinant vaccines against the new coronavirus mainly target the RBD region of the S protein of SARS-CoV-2 for vaccine design
.
The first recombinant protein vaccine approved for clinical use in the world is ZF2001, which was jointly developed by Anhui Zhifeilongke Biology and the Institute of Microbiology, Chinese Academy of Sciences
.

1.
4 Viral vector vaccines

Viral vector-based vaccines are vaccines formed by embedding exogenous protective antigen genes into the vector with a non-pathogenic virus as a carrier
.
Commonly used vectors: adenovirus, influenza virus, herpes virus, salmonella,
etc.

Ad5-nCoV was jointly developed by the Academy of Military Medical Sciences and CanSino, and is the first adenovirus vector new crown vaccine developed in China
.
ChAdOxnCoV-19 was jointly developed by Oxford University and AstraZeneca
.
The Russian Sputnik-V vaccine utilizes two different adenoviruses, Ad5 and Ad26, as vectors
.

1.
5 Nucleic acid vaccines

Nucleic acid vaccines are "third-generation vaccines" and are a new type of vaccine.
They are divided into two types: DNA vaccines and mRNA vaccines
.
Nucleic acid vaccines express foreign antigens in host cells to induce immune responses in the body
.

1.
5.
1 DNA vaccines

DNA vaccines are constructed from plasmid DNA containing mammalian expression promoters and encoding spike protein antigens.
Compared with traditional methods, DNA vaccines can induce a broad range of immune responses, are thermostable, can encode multiple antigens in a single vaccine, Efficient bacterial mass production and cost-effectiveness
.

In September 2021, the world's first new crown DNA vaccine "ZyCoV-D" was approved in India by emergency authorization.
The vaccine was developed by the Indian pharmaceutical company Zydus Cadila.
It can penetrate the skin without needle injection and can avoid the pain caused by injection
.
AG0301-COVID19, a vaccine candidate developed by Anges Inc.
and Osaka University, has also entered clinical phase I/II
.

1.
5.
2 RNA vaccines

mRNA vaccines contain an RNA molecule encapsulated in lipid nanoparticles (LNPs)
.
After intramuscular injection, LNP-mRNA is internalized in host cells and serves as a template for the synthesis of the long spike protein antigen
.
Compared with traditional methods, mRNA vaccines offer several advantages in terms of safety, cost-effectiveness, induction of cellular and antibody-mediated immune responses
.

The mRNA vaccine BNT162b1/2 jointly developed by Pfizer and BioNTech is a lipid-based nanoparticle nucleotide-modified vaccine
.
mRNA-1273 was jointly developed by Moderna and the NIH
.

About the new coronavirus variant strain

About the new coronavirus variant strain

The new coronavirus belongs to the Coronaviridae family of the order Enveloped virus, and is an RNA virus
.
Unlike the human DNA genome, the genome encoding the genetic information of the new coronavirus is an RNA molecule
.
When the new coronavirus reproduces, the RNA molecule will replicate under the action of RNA replicase, and then enter the progeny virus to form an infectious virus particle
.
However, when RNA complexase catalyzes RNA replication, the fidelity is relatively low, and it is prone to errors, which can lead to mutations in the viral RNA genome
.
This is the main reason why the new coronavirus keeps producing mutants
.

This is the main reason why the new coronavirus keeps producing mutants
.

In fact, all viruses that use RNA as the carrier of genetic information, such as influenza virus, HIV, etc.
, are prone to mutant strains due to the low fidelity of RNA replicase or reverse transcriptase during RNA replication
.
This is also an important reason why it is necessary to constantly replace and upgrade vaccine varieties to prevent these diseases, or it is simply difficult to develop an effective vaccine
.

All viruses that use RNA as a carrier of genetic information, such as influenza virus, HIV, etc.
, are prone to mutant strains due to the low fidelity of RNA replicase or reverse transcriptase during RNA replication
.

The novel coronavirus generates new variants by accumulating point mutations, gene recombination, and gene insertion or deletion within its genome, and these changes may directly affect its pathogenesis, transmission potential, and changes in disease severity
.

According to the public health risk of the virus, the WHO has divided the new coronavirus variant strains into three groups in turn
.
The first one is the "mutant of concern" (VOC, variant of concern) , including Alpha (corresponding to PANGO lineage B.
1.
1.
7), Beta (B.
1.
351), Delta (B.
1.
617.
2), Gamma (P.
1) and Omicron (B.
1.
1.
529) mutants (Fig.
3); the second is a "mutant to be observed" (VOI, variant of interest) , including Lambda (C.
37) and Mu (B.
1.
621) mutant strain; the third is "variant strain under monitoring" (VUM, variant under monitoring) , December 22, 2021, this group includes 5 mutant strains
.

"VOC, variant of concern " (VOI, variant of interest) "VUM, variant under monitoring"

Figure 4 shows the new coronavirus variant strain (VOC), from "New coronavirus variant strain and vaccine research status"

Statistics from the World Health Organization (WHO) show that from January 10 to February 10, 2022, 96.
7% of the samples that were genetically sequenced and uploaded to the "Global Initiative for Influenza Data Sharing" database were infected with Omic Rong strain, while the proportion of delta strain infection was only 3.
3%
.

Studies have shown that the Omicron variant in South Africa spreads faster than the Delta variant, but the clinical symptoms caused by the Omicron variant are milder than that of the Delta variant, causing more mild to moderate clinical symptoms
.
At the same time, Omicron virus mutation changes the antigenic properties of the virus, reducing the protective efficacy of existing vaccines against virus infection and transmission
.
ChenJ et al.
constructed a deep learning model based on algebraic topology.
Through comparative analysis of all the main variant strains, it was shown that the infectivity of BA.
2 was 1.
5 times and 4.
2 times that of BA.
1 and Delta, respectively
.
The vaccine escape potential of BA.
2 was also 30% and 17 times higher than that of BA.
1 and Delta, respectively
.

BA.
2 is 1.
5 times and 4.
2 times more infectious than BA.
1 and Delta, respectively
.
The vaccine escape potential of BA.
2 was also 30% and 17 times higher than that of BA.
1 and Delta, respectively
.

Status of new crown vaccine prevention and control

Status of new crown vaccine prevention and control

At present, the WHO has approved emergency use authorization for nearly 20 new crown vaccines
.
China has approved 4 new crown vaccines for domestic listing with conditions, including 2 inactivated vaccines from Sinopharm Group, 1 inactivated vaccine from Beijing Kexing and CanSino's adenovirus vector vaccine
.
China's other three new crown vaccines have obtained the domestic emergency use authorization certification, namely the recombinant subunit vaccine, the Kangtai inactivated vaccine and the Keweifu inactivated vaccine developed by the Institute of Microbiology of the Chinese Academy of Sciences and Anhui Zhifei
.
Sinopharm (Beijing) and Sinovac vaccines have been recognized by WHO and exported to dozens of countries around the world
.

As of April 24, Oxford University's Our World in Data statistics have reported that 11.
53 billion doses of the new coronavirus vaccine have been administered worldwide, with a vaccination rate of 65.
08%
.

Figure 5 shows the new crown drugs approved or authorized for emergency use worldwide, from "2021 New Crown Virus Variation, Cross-species Transmission, and a Review of Hot Spots in Vaccine and Drug Research"

New crown vaccine effect

New crown vaccine effect

A vaccine effectiveness study in the UK found that two doses of the BNT162b2 vaccine [Pfizer; mRNA vaccine] were 93.
7% effective against the Alpha strain and 88% effective against the Delta strain; two doses of ChAdOx1nCoV The -19 vaccine [AstraZeneca; adenovirus vector vaccine] was 74.
5% effective against the Alpha strain and 67% effective against the Delta strain; and the protective efficacy of vaccination decreased over time
.
However, an efficacy study in Qatar showed that two doses of the BNT162b2 vaccine were only 51.
9% effective against the Delta strain, two doses of mRNA-1273 (Moderna) were 73.
1% effective against the Delta strain, and two Vaccines are effective in reducing severe illness and death
.

The domestic new crown vaccine is widely used around the world and has been recognized by many countries.
It has shown good protective efficacy in the results of pre-clinical trials and real-world studies
.
In April 2021, the Chilean Ministry of Health reported the real-world protective efficacy data of China's new crown vaccine in Chile.
The results of a large-scale cohort study showed that the overall efficacy rate of the Sinovac vaccine was 65.
9%, and the effective rate of preventing death caused by infection was 86.
3%.

.
The domestic Kexing vaccine has been tested in the elderly over 60 years old, adults aged 18 to 59 years, and children and adolescents aged 3 to 17.
The test results also showed that the positive conversion rate of neutralizing antibodies in each dose group reached 79% to 100%, and the protective effect was good.

.
In May 2021, the results of the Phase III clinical trial of China's new crown virus vaccine were first published.
14 days after two injections of two new coronavirus inactivated vaccines of China Biotechnology, high titer antibodies were produced, and the positive conversion rate of neutralizing antibodies in the whole population reached 99%.
above
.
Adenovirus vector vaccine Ad5-nCoV and recombinant protein vaccine ZF2001 also showed good immunogenicity in adults aged 18-59
.

Summarize

Summarize

By the end of 2021, China's full-course vaccination rate has exceeded 85%, and by the end of February 2022, it has exceeded 87%.
It is necessary to promote sequential strengthening of immunization to further improve the immunization effect
.

"If too few people are vaccinated and the spread of the virus cannot be controlled, there will be infections, mutations ," said Mehul Suthar, a virologist at Emory University.
and an infinite loop of propagation
.
"

"If too few people are vaccinated and the spread of the virus cannot be contained, there will be an endless cycle of infection, mutation and transmission
.
"

Variant vaccines have a long period from research and development to being put into use.
Therefore, using homologous vaccines to strengthen immunity is still a feasible solution to prevent the outbreak of the epidemic
.
In view of the constantly mutating virus, while fully carrying out basic research and using homologous vaccines to strengthen immunity, it is still necessary to develop and produce a new crown vaccine with strong antibody durability and high safety in the future
.

New crown vaccination is still the most effective way to prevent new coronavirus infection at present .
Whether it is against immune escape or a new coronavirus variant with enhanced infectivity, the new crown vaccine can still play a good protective role, not only reducing severe cases, but also reducing deaths.
rate
.

Covid-19 vaccination remains the most effective way to prevent Covid-19 infection

Vaccination strategies of different immunization routes are beneficial to improve the protective efficacy of vaccines
.
Vaccination by intramuscular injection causes a systemic long-lasting IgG antibody response and produces long-lasting memory cells; then, combined with non-injectable vaccines for respiratory inoculation, memory cells are recruited into the nasal cavity, induce mucosal immunity, and finally obtain long-lasting protection Sexual immunity may be one of the ideal vaccination strategies to obtain durable immunity
.

Vaccination strategies of different immunization routes are beneficial to improve the protective efficacy of vaccines
.

The mucosal immune system can locally produce specific sIgA antibodies to form the first-line immune barrier against virus invasion
.
Nasal spray or oral vaccination can make the body's respiratory mucosa or intestinal mucosa gain the ability to resist the corresponding infectious diseases
.
Therefore, new dosage forms of new crown vaccines such as nasal spray, oral or aerosol inhalation are also an important research direction
.

New dosage forms of new crown vaccines such as nasal spray, oral or aerosol inhalation are also an important research direction
.

References:

References:

1.
"Current Situation of Novel Coronavirus Variants and Vaccine Research"

1.
"Current Situation of Novel Coronavirus Variants and Vaccine Research"

2.
"Review of 2021 New Coronavirus Variation, Cross-species Transmission, and Research Hotspots of Vaccines and Drugs"

2.
"Review of 2021 New Coronavirus Variation, Cross-species Transmission, and Research Hotspots of Vaccines and Drugs"

3.
Why is the epidemic in Shanghai so fierce? How powerful is the Omicron BA.
2 strain?

3.
Why is the epidemic in Shanghai so fierce? How powerful is the Omicron BA.
2 strain?

4.
Other public information

4.
Other public information