Scientists now recommend mixing of AstraZeneca and Pfizer COVID-19 vaccines

Kenya is yet to decide whether or not it will mix and match shots of the COVID-19 AstraZeneca and Pfizer vaccines after Oxford University-driven research indicated that receiving the two different shots as first and second dose induced higher antibodies.

This comes as the country awaits over 1 million doses of the Pfizer vaccine donated by the United States government from next week.

The race to achieve herd immunity is one that is slowly outpacing the world, given vaccine supply challenges; this occurring amidst surging COVID-19 infections across the globe owing to the delta variant.

But a recent report from the Com-Cov study trial spearheaded by the University of Oxford indicates that a mix-and-match approach to COVID-19 vaccines will help alleviate these issues and create more flexibility in the immunization regimens available to people.

The Com-Cov study, which looked at giving the doses four weeks apart in 850 volunteers aged 50 and above, found that AstraZeneca followed by Pfizer induced higher antibodies and T cell responses than Pfizer followed by AstraZeneca.

Additionally, both of these mixes induced higher antibodies than two doses of AstraZeneca.

“It is good, it is reassuring, both have been tested, and there are obviously many more, but what I do not think we can do is to provide general recommendation that you can mix and match the way you want. This is product specific,” said Dr. Joachim Hombach, Executive Secretary, Sage/Immunization – WHO.

In Kenya, the Ministry of Health is yet to determine whether or not the mix and match approach will be a viable option. So far, 1.74 per cent of the population has been fully vaccinated.

“Yes, data is emerging but still this is some work in the pipeline. In some countries like Spain and Germany have given two different doses so we will also await data from them to be able to guide us,” said Acting Director General of Health Dr. Patrick Amoth.

A smaller study from Germany’s Saarland University also showed a stronger immune response in patients who received AstraZeneca followed by Pfizer than they did in patients who had received two doses of the AstraZeneca vaccine.

However, both studies have not gone through the peer-review process where independent scientists evaluate them.

“More data will be coming but it is a great addition to flexibility, but whether it is a general principle that could be applied is something to be determined,” added Dr. Hombach.

According to Dr. Amoth, “…that is why it is also important for us to get more vaccines so that can also trial those in our own local setting.”

Kenya is hoping to scale up vaccination with the arrival of 13 million doses of the one shot Johnson & Johnson vaccine as well as 1.6 million doses of the Pfizer.