"Vaccine Effectiveness: AZ-Pfizer Cross Vaccination > AZ Two Doses"

Vaccination Order Also Influences Outcomes

An elderly person is receiving a COVID-19 vaccine at the vaccination center in Yongsan-gu, Seoul, on the 3rd amid the imbalance in COVID-19 vaccine supply./Photo by Hyunmin Kim kimhyun81@

[Asia Economy Reporter Cho Hyun-ui] A study in the UK has found that mixing AstraZeneca (AZ) and Pfizer COVID-19 vaccines produces a stronger immune response than receiving two doses of the AZ vaccine.

On the 28th (local time), BBC and The Guardian reported, "The Oxford University 'Com-COV' study compared mixed AZ-Pfizer vaccination with two doses of each vaccine," highlighting these findings.

The study involved over 800 participants aged 50 and above. The interval between the first and second doses was set at 4 weeks.

The results showed that the antibody response was highest with two doses of Pfizer, while the immune cell response was strongest when Pfizer was administered after AZ.

The order of vaccination also influenced the response. Receiving Pfizer after AZ resulted in higher antibody and immune cell responses than receiving AZ after Pfizer.

BBC stated, "These findings suggest that people who received two doses of the AZ vaccine may exhibit a stronger immune response if they receive a different vaccine as an additional dose."

However, it was explained that receiving only the AZ vaccine does not mean reduced effectiveness. BBC emphasized, "Two doses of the AZ vaccine reduce the risk of hospitalization due to COVID-19 by more than 90%."

Professor Matthew Snape of Oxford University explained, "The scale of this study is not large enough to provide grounds for a major change in the clinically validated same-vaccine vaccination policy."

Professor Jonathan Van-Tam, Deputy Chief Medical Officer for England, also said, "There is no reason to change the current same-vaccine vaccination policy as long as vaccine supplies are sufficient." He added, "Mixed vaccination offers policy flexibility for booster doses and will help countries with vaccine shortages."

Countries such as Germany, the UK, Spain, and Canada have already implemented mixed vaccination. Early studies in Germany and Spain showed that mixed vaccination is more effective.

A research team at Charit? Hospital in Berlin, Germany, reported that individuals who received mixed AZ-Pfizer vaccination experienced fewer systemic reactions (fatigue, headache, etc.) than those who received two doses of Pfizer only. The Carlos III Health Institute in Spain announced that immune responses were 30-40% higher with mixed AZ-Pfizer vaccination compared to two doses of AZ.

However, the Oxford University study in the UK reported that the proportion of participants who reported fever after mixed vaccination was 34-41%, higher than 10% for two doses of AZ and 21% for two doses of Pfizer. No serious adverse reactions were observed.

This content was produced with the assistance of AI translation services.