2nd AZ·Pfizer·Moderna shot prevents variants by 80%

NECA and KAMS jointly conducted a rapid review on COVID-19 vaccines

Mixed use of vaccines can increase systemic reactions at an acceptable level

Study results on the preventive effect of the AstraZeneca, Pfizer, and Moderna vaccine against variants showed that the vaccines had a preventive effect of over 80% after completing the two-dose regimen.

 

The prevention effect was greater against the Alpha variant than the Delta.

 

In preventing symptomatic infections, the vaccines had a similar prevention effect against variants and the original virus.

 

Mixed vaccination using the AstraZeneca and Pfizer vaccine showed a neutralizing antibody response that was similar or higher than that of those using two shots of the same vaccine and the systemic reaction was at an acceptable level.

 

The National Evidence-based Healthcare Collaborating Agency (NECA, President: Kwang-hyub Han) and the Korean Academy of Medical Sciences (KAMS, President:Ji-Tae Choung) jointly presented the results of the "Rapid review on issues regarding COVID-19 vaccines" study on the 15th.

 

On the preventive effect of the current COVID-19 vaccines against variant strains such as the Alpha, Beta, Gamma, and Delta strains, the vaccines demonstrated a clinically significant effect (prevention of symptomatic infections, hospitalizations, and death).

 

Regarding the preventive effect of the vaccines against variants, the vaccines were slightly less effective against the variants compared to the original virus, but still, the vaccine had a preventive effect of over 80% when subjects completed the two-dose regimen.

 

The vaccines had a stronger preventive effect against the Alpha variant than the Delta.

 

In preventing symptomatic infections, the preventive effect was of the vaccines was at a similar level for variants and the original virus.

 

When completing a single shot of vaccination, the risk of hospitalization and deaths from variant infection was reduced by 78-96%, and after the second shot, by 86-96%.

 

Also, the vaccines' effect on reducing hospitalization and deaths was not largely different against different types of variants, however, the data available as of now were insufficient to discern the severity of the events.

 

Mixed vaccination using the AstraZeneca and Pfizer vaccine showed a neutralizing antibody response that was similar or higher than that of those using two shots of the same vaccine.

 

Systemic reactions increased after the use of mixed vaccines, but at an acceptable level.

 

On the immunogenicity after receiving mixed vaccinations, the study showed that receiving mixed vaccinations also elicited a neutralizing antibody response against the COVID-19 virus.

 

In general, immune response increased after mixed vaccinations compared to two doses of the AstraZeneca vaccine, and was similar or higher than that measured after two doses of an mRNA vaccine (Pfizer, Moderna).

 

The mixed vaccination had increased systemic response compared to two doses of the same vaccine, but was tolerable and at an acceptable level.

 

However, as only short-term safety studies existed on mixed vaccination, it was difficult to evaluate the adverse events that have a low incidence using studies based on the current scale.

 

The mixed vaccination regimen had increased immune response against the variants compared to two shots of the AstraZeneca vaccine and had an increased or reduced effect compared to two shots of the Pfizer vaccine, depending on the type of variant.

 

But the limitation was that only small-scale studies with limited results existed for review.

 

No direct studies on preventing infections were available and only studies with immunogenicity results existed for review.

 

Mi-young Choi, head of Clinical Evidence Research Team at NECA said, “This study was the first systemic literature review conducted on the use of mixed dose vaccinations and activities against the variant strains.

 

As most of the reviewed literature were studies in progress or unpublished, quantitative and qualitative limitations do exist in our study.” KAMS Policy Director Ho-kee Yum (Chair of the Expert Committee for COVID-19 Response, Korean Medical Association) said, "We can predict and respond to new infectious diseases to a certain extent by studying existing clinical data.

 

I believe the release of reliable study results from a medical society and the government like this will contribute greatly to reducing the public anxiety that has been rising recently and in overcoming the pandemic.”