Updated: Mar 14
Before the emergence of the Omicron variant, evidence showed the enhanced effectiveness of combining two different COVID-19 vaccines in preventing the disease and protecting us against the Delta variant with the potential to influence the system going forward.
The natural experiment of mix-and-matching COVID-19 vaccines began last March because of the extremely rare but serious side effects that occurred from the AstraZeneca vaccine. The negative outcomes resulted in halting the distribution of the AstraZeneca and using a different vaccine as the second dose. Three studies have independently confirmed the increased effectiveness of mix-and-match regimens for various populations at various times — including during the rise of the hyper-infectious Delta variant — and enhanced immune response among immunosuppressed individuals.
Although the effectiveness of the mix-and-match COVID-19 vaccines regimen is now well-established, how well this vaccine regimen will hold up over time and whether and when boosters are needed is still to be determined. Further research is required to determine whether the mix-and-match vaccine regimen will be an effective defense against the heavily-mutated Omicron variant.
Read more here.