An essential booster to mitigate the effects of Omicron, but can lose some effectiveness | Imperial News

The new report states that it is predicted that the levels of neutralizing antibodies to prevent Omicron infections will decrease and the effectiveness of the vaccine against severe diseases will decrease.

Vaccines have played a central role in reducing the serious illness and mortality of COVID-19 over the last 12 months. However, the emergence of the variant of concern has reduced the effectiveness of the vaccine against mild and subsequent infections. The degree of debilitation for severe illness (ie, requiring hospitalization) is less than the degree of debilitation for mild illness, but even a slight decrease in protection is a significant increase in hospitalization and mortality, especially in the high-risk group. May bring.

Vaccine efficacy

In this latest report by the COVID-19 Response Team at Imperial College, researchers adapted an immunological model to population-level vaccine efficacy data to determine vaccine efficacy in the face of Omicron variants.

Our estimates suggest that this is likely to lead to a small but significant reduction in efficacy against severe illness and death. Professor Azra Ghani

After two initial doses and booster vaccine with mRNA vaccine (Pfizer BioNTech or Moderna), neutralizing antibodies (preventing infection) were 1.6 times (95% reliable interval, CrI) compared to levels after 2 doses. 1.4–1.9) Estimated to increase. 3.3 times (95% CrI 2.5-4.7) with the Pfizer-BioNTech vaccine compared to the levels after two doses of the Oxford-AstraZeneca vaccine. However, researchers have found that when the immune system encounters a variant, the level of neutralizing antibody produced against Omicron is 4.5 times higher than that produced against the delta variant (95% CrI 3.1–7.1). ) It is estimated that it may be lower.

Important booster dose

Researchers have also found that this reduction in neutralizing antibodies may affect the effectiveness of the vaccine against serious illnesses. In the worst-case scenario, where the rate of decay after booster administration is the same as that observed after the first two doses, this study found that vaccine efficacy against serious disease (hospitalization) was 96.5% (95% CrI 96.1%). – If the antibody disintegrates from 96.8% for Delta by 60 days after the primary vaccine course to 80.1% for Omicron (76.3% –83.02) and then at the same rate as after the booster observed after the primary vaccine. Pfizer-BioNTech Vaccine Booster Course. If this decay factor is half that, the decline is estimated to be from 97.6% (95% CrI 97.4% -97.9%) for Delta to 85.9% (95% CrI 83.1% -88.3%) for Omicron. However, this may be further alleviated by extending the lifespan of T-cell-mediated immunity.

Researchers say these numbers are currently associated with a high degree of uncertainty, but are likely to require specific vaccines of the Omicron variant and / or additional booster immunity to restore protection. It states that it shows.

Global vaccine distribution

This report considers how this immunological model should be integrated with the SARS-CoV-2 virus infection model to optimally deploy booster doses in light of the current pandemic situation. .. Researchers model three scenarios. One has significant past infections (and adaptive immunity) and has high access to vaccines, one has significant past infections but limited access to vaccines, and the other. One is the so-called “zero COVID” country where past infections are limited.

Boosters will be an important part of policy response to reduce hospitalizations and deaths and prevent overloading the healthcare system. Dr. Alexandra Hogan

Their findings show that booster doses are important to mitigate the effects of future Omicron waves in countries with high levels of circulating virus.

In “Zero COVID” countries, booster effects are also needed to prevent new waves of infection and safely initiate infection.

If vaccine supply is restricted or vaccine deployment is delayed, directing booster doses to the highest risk groups to ensure continued high protection in the face of weakened immunity can be a good idea. These doses are a great advantage over giving the younger age group as a primary vaccination.

Researchers say it is not yet known how serious the disease caused by the Omicron mutant is compared to the disease caused by the previous mutant.

Professor Azra Ghani Comment from Imperial College London: “Given the rapid proliferation of Omicron variants so far, this is very likely to replace the globally circulating Delta variant in the coming weeks. Immunogenicity data clearly show a significant reduction in neutralizing antibodies, but preliminary vaccine efficacy estimates indicate a significant reduction in protection from mild disease. Our estimates suggest that this is likely to lead to a small but significant reduction in efficacy against severe illness and death. One of the remaining uncertainties is that of Omicron. How serious the disease caused by the subspecies is compared to the disease caused by the previous subspecies. It may take weeks to fully understand this, but the government has the potential. We need to plan now to mitigate the effects. Our results show the importance of providing booster doses as part of a broader public health response. Prioritizing these boosts over high-risk populations over initial vaccination should be part of this response in countries with limited dose supply. “

Dr. Alexandra Hogan Imperial College London said: “Although data are still available, the rapid spread of the Omicron variant is of great concern in countries where the virus continues to circulate and in countries where infection was previously suppressed and now lifted. Both have predicted a significant increase in infections and cases in the coming weeks. Our study makes booster doses an immediate priority, especially in the elderly, high-risk, and high-priority populations. It provides further evidence of the importance of providing. Although the effects of Omicron on the severity of the disease are not yet fully understood, boosters reduce hospitalizations and deaths and the medical system is overloaded. It will be an important part of the policy response to prevent it from becoming. “

This unreviewed study is presented in the latest report from the WHO Collaborative Center for Infectious Disease Modeling within the MRC Center for Global Infectious Disease Analysis at the Jameel Institute, Imperial University of London.

Since the advent of the new coronavirus (COVID-19) in December 2019, Imperial College’s COVID-19 response team has adopted a policy of immediately sharing findings on an outbreak of pandemic.