Mixing two vaccines 'seems to be working well': WHO scientist

As governments and pharma companies all over the world prepare to bring out boosters targeting more contagious virus variants, World Health Organisation (WHO) Chief Scientist Dr. Soumya Swaminathan has stated that nations where people have got at least one dose of the COVID-19 vaccine but are now facing shortages don't need to count on these. Swaminathan stated that heterologous prime-boost immunisation or immunisation using a combination of vaccines could be of big help for these countries instead.  

WHO defines heterologous prime-boost immunisation as a form of vaccination wherein two different vectors or delivery systems expressing the same or overlapping antigenic inserts are administered.

Also read: South Korea to mix-and-match Pfizer, AstraZeneca COVID-19 vaccines

 "It seems to be working well, this concept of heterologous prime-boost," Swaminathan said during a recent Zoom interview. "This opens up the opportunity for countries that have vaccinated people with one vaccine and now are waiting for the second dose they have run out of, to potentially be able to use a different platform vaccine", she said while expounding on its benefits.

She further cited data from the UK, Spain and Germany which suggests that 'mix-and-match' regimen involving two different types of COVID-19 vaccines generates more robust immune response (higher levels of virus-blocking antibodies and white blood cells that kills virus-infected cells) even though there are some side effects like pain, fever and other minor side effects.

Malaysia is also mulling using combinations of the AstraZeneca and Pfizer-BioNTech shots in a bid to speed up inoculations, Science, Technology and Innovation Minister Khairy Jamaluddin mentioned earlier this week.

Also read: COVID-19 vaccines: No mixing of different doses; stick to SOP, says govt

Swaminathan's pitch for combination vaccination was backed by several experts. Director of the Vaccine Education Center at the Children's Hospital of Philadelphia director Paul Offit said that inoculating using a combination of jabs is likely to offer longer immunity or fewer side effects for certain individuals, adding basic requirement of a vaccine is to protect against hospitalisation, ICU admission and death.

"With that bar, we probably would need a vaccine maybe every three to five years," he said in a STAT podcast.

Edited by Mehak Agarwal

Also read: India to soon test mixing two different COVID-19 vaccines