How effective is the new crown vaccine?

The Omicron variant of the new coronavirus has spread to more than 100 countries and regions around the world, and in some of those areas where there is widespread local transmission, Omicron has become the dominant strain
.

Compared to previously popular variants, Omicron has a large number of key mutations, including as many as 32 mutations in the spike protein, some of which may be associated with immune escape and higher infectivity

There are limited data on how vaccines and previous infections prevent Omicron-induced infection, transmission, clinical illness, and death
.

Recently, the "New England Journal of Medicine" (NEJM) published three important papers in a row, exploring the effect of the new crown vaccine on Omicron from different perspectives such as real-world observation data and laboratory research

The first study, from South Africa, where omicron is highly prevalent, analyzed fully vaccinated Covid-19 vaccine (two doses of BNT162b2) based on data from 15 November 2020 (75% of positive cases sequenced with omicron detected) - 7 December 2020 For the effectiveness of preventing COVID-19 hospitalization after Omicron infection, compared with data from the previous epidemic period of Delta variant (September 1-October 30, 2020)
.

The analysis included 133,000 nucleic acid test results in the Delta epidemic period and 78,000 nucleic acid test results in the Omicron epidemic period (28.
6% and 41.
4%, respectively, were obtained at least 14 days after patients received the second dose of vaccine)
.

The data shows that the positive rates of nucleic acid tests in the Delta epidemic period and the Omicron epidemic period were 6.

The vaccine was estimated to be 70% effective in preventing hospitalization during the Omicron epidemic, which was also supported by all three sensitivity analyses for different subgroups
.

In the Delta epidemic period, this figure was 93%

The research team proposed that the effectiveness of the two-dose BNT162b2 vaccine against COVID-19 hospitalization after Omicron infection was maintained, but decreased compared to the Delta epidemic period, and booster vaccination may help improve the effectiveness
.

The other two studies were in vitro experiments based on serum samples
.

One, from the Israeli Ministry of Health, compared sera from two doses (20 people, an average of 165.

The results show that:

For both the wild-type 2019-nCoV and the three variants, receiving three doses of the vaccine resulted in better neutralization than two doses (in geometric mean titers, Figure A/C below)
.

Compared with serum samples from three-dose vaccine recipients (Figure D below), serum samples from two-dose vaccine recipients showed a more significant difference in neutralization effect against the three variants and wild-type viruses (Figure B below)
.

Both the two-dose and three-dose vaccines were less effective at neutralizing Beta and Omicron
.

Compared with serum samples 5 months after receiving two doses of the vaccine, which almost lost their ability to neutralize Omicron, the serum of the third dose of BNT162b2 vaccine recipients could effectively neutralize Omicron infection with a 100-fold increase in neutralization efficiency
.

"The importance of the third dose of vaccine is obvious, but even with three doses, neutralization of the Omicron variant is still 4-fold lower than that of Delta, and the persistence of the third dose remains to be determined," the paper states.

.

"

Pseudovirus neutralization studies from Rockefeller University also showed that although Omicron variants showed a considerable degree of escape from neutralizing antibodies, booster vaccination compared to two doses of mRNA vaccine (BNT162b2 or mRNA-1273) Post-acupuncture plasma samples had higher levels of neutralization of Omicron, and recovered individuals were also given additional protection after vaccination
.

Specifically, the research team obtained a total of 169 plasma samples from 47 participants and analyzed their effects on the original strain, PMS20 pseudovirus and Omicron spike protein pseudovirus
.

These participants were either naturally infected with the new coronavirus, vaccinated, or both

PMS20 pseudovirus: Refers to the introduction of nearly 20 mutations on the synthetic spike protein.
Previous studies have suggested that the PMS20 pseudovirus is sufficient to substantially reduce the effect of neutralizing antibodies in most survivors or in two-dose mRNA vaccine recipients
.

The results showed that immunity declined over time and was affected by the mutation:

In plasma samples 1 month, 6 months and 1 year after natural infection, the neutralizing effect of PMS20 pseudovirus (measured by 50% neutralization titer [NT50]) was 60-fold and 37-fold lower than that of the original strain, respectively and 34 times, the neutralization effect of Omicron pseudovirus was reduced by 58 times, 32 times and 43 times, respectively
.

Plasma samples at 1.
3 months and 5 months after inoculation with two doses of mRNA vaccine have 187-fold and 58-fold lower neutralization effects on PMS20 pseudovirus than the original strain, and 66-fold and 66-fold lower neutralization effects on Omicron pseudovirus, respectively.
27 times
.

In contrast, vaccination of recovered individuals, or continued administration of a third dose (at least 6 months from the second dose) in the mRNA-vaccinated population, significantly increased neutralizing activity against PMS20 and Omicron
.

After vaccination, the neutralization effects of the original strain, PMS20 and Omicron pseudoviruses were increased by 238 times, 214 times and 154 times, respectively
.

One month after inoculation of the third dose of mRNA vaccine, the neutralization effect of the original strain, PMS20 and Omicron pseudoviruses was increased by 26 times, 35 times and 38 times, respectively
.

New variants emerge in an endless stream, and Omicron is threatening, but under the guidance of scientific research, I believe that targeted prevention and control measures can still build a line of defense for us
.

With the popularization of vaccines and the advent of drugs, it is also expected that the impact of the epidemic will fade as soon as possible

References

References

[1] Shirley Collie, et al.

[1] Shirley Collie, et al.
, (2021).
Effectiveness of BNT162b2 Vaccine against Omicron Variant in South Africa.
The N Engl J Med, DOI: 10.
1056/NEJMc2119270

[2] Ital Nemet, et al.
, (2021).
Third BNT162b2 Vaccination Neutralization of SARS-CoV-2 Omicron Infection.
The N Engl J Med, DOI: 10.
1056/NEJMc2119358

[2] Ital Nemet, et al.
, (2021).
Third BNT162b2 Vaccination Neutralization of SARS-CoV-2 Omicron Infection.
The N Engl J Med, DOI: 10.
1056/NEJMc2119358

[3] Fabian Schmidt, et al.
, (2021).
Plasma Neutralization of the SARS-CoV-2 Omicron Variant.
The N Engl J Med, DOI: 10.
1056/NEJMc2119641

[3] Fabian Schmidt, et al.
, (2021).
Plasma Neutralization of the SARS-CoV-2 Omicron Variant.
The N Engl J Med, DOI: 10.
1056/NEJMc2119641

[4] Enhancing Readiness for Omicron (B.
1.
1.
529): Technical Brief and Priority Actions for Member States.
Retrieved January 5, 2022 from https:// for-omicron-(b.
1.
1.
529)-technical-brief-and-priority-actions-for-member-states

[4] Enhancing Readiness for Omicron (B.
1.
1.
529): Technical Brief and Priority Actions for Member States.
Retrieved January 5, 2022 from https:// for-omicron-(b.
1.
1.
529)-technical-brief-and-priority-actions-for-member-states