South Korea Study: Mixed AstraZeneca-Pfizer Vaccination Increases Antibodies

Covid-19 inoculation with AstraZeneca first, followed by Pfizer, boosts neutralising antibodies by six times compared to two AstraZeneca shots, according to a South Korea study.

KUALA LUMPUR, July 29 — A new South Korean study showed that mixing AstraZeneca and Pfizer-BioNTech vaccines boosted neutralising antibody levels against Covid-19.

Reuters reported that the heterologous vaccination with AstraZeneca first and Pfizer for the second dose improved Covid-19 antibody levels six times more than receiving two doses of AstraZeneca. The mixed inoculation reportedly produced similar amounts of neutralising antibodies as receiving two Pfizer doses. 

A total of 499 health care personnel took part in this study, conducted by the Korea Disease Control and Prevention Agency.

Of them, 100 people received mixed doses of vaccination, while 200 received double Pfizer shots. The remaining participants received two shots of AstraZeneca vaccine. 

This study investigated the effects of mixing certain vaccine doses and vaccine efficacy against variants of concern like Alpha, Beta, Gamma, and Delta.

The vaccination groups in the South Korean research reportedly did not show poorer neutralisation against Alpha. However, neutralising activity decreased between 2.5 and six times for other coronavirus variants such Beta, Gamma and Delta.

Oxford University also conducted a similar study in June which showed that mixed AstraZeneca-Pfizer shots — either AstraZeneca or Pfizer as first dose — produced better immune responses compared to two doses of AstraZeneca.

In fact, Thailand also recently announced that it will use AstraZeneca as a second dose for those who received the first dose of the Sinovac vaccine, after a new preliminary Thai study appeared to find decreasing protection from complete inoculation with Sinovac.

However, the World Health Organization warned individuals not to use the mix-and-match vaccination approach as only public health authorities should make such decisions.

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