Why it’s too early to mix and match coronavirus vaccines
The primary objective of vaccination is to achieve a robust and lasting immunity against a disease.
What you need to know:
- Mixing and matching drugs is not novel
- But, the certainty of safety and efficacy have to be backed by scientific studies
Vaccine strategy is often a delicate balance of thoughtful preparation and strong execution, with health officials forced to act with imperfect information and use scarce resources across a broad population.
As scenarios evolve, our strategy should not involve mixing and matching Covid-19 vaccines, just yet.
The primary objective of vaccination is to achieve a robust and lasting immunity against a disease.
This encompasses induction of an enduring immunologic memory towards the offending pathogen (antigens) and production of persistent antibodies against the antigens.
Vaccines achieve this by teaching the body to recognise an offending pathogen by introducing either a weakened part or inactivated form of a pathogen and allowing the body to develop an effective response without the potential of causing a disease.
Blood clot claims
Newer vaccines use mRNA technology to provide the body with instructions on how to make spike proteins specific to the offending pathogens.
The idea of mixing and matching Covid-19 vaccines, is not yet feasible as studies are still ongoing.
Mixing and matching drugs is not novel. But, the certainty of safety and efficacy have to be backed by scientific studies.
This is because of the potential of drugs to interact, normally referred to as drug-drug interactions. These interactions can culminate in an enhanced efficacy, increased propensity to cause untoward effects hence toxicity or decreased efficacy.
While the prospects of an enhanced efficacy are alluring, we have to be wary of the prospects to enhance toxicity especially in the wake of blood clot claims.
We, therefore, urge the government to take advantage of the eight-week time lag approved as feasible between the first and second doses of the AstraZeneca vaccine to procure more of the vaccines used in the first dose to use in the second vaccination batch.
This can be prioritised even as we await results from the clinical trials looking at the effects of mixing vaccines.
