Covid-19 | Oxford’s study supports ‘mix-and-match’ vaccination schedule

On the heels of the Macau SAR government saying it has not ruled out the possibility of mandating the administration of a “Covid-19 vaccine cocktail,” — referring to the administration of different types of vaccines for the first and second shots — Oxford researchers announced later in the day that the so-called “mix-and-
match” approach can indeed boost immunity against the virus.
“The preliminary data [by research conducted by other instituions] shows that the efficiency, or the antibody concentration, is higher [for people taking the vaccine cocktail] when compared with taking a single type of vaccine,” Tai Wa Hou, coordinator of the Health Bureau’s Covid-19 Vaccination Operation, said on Monday before the release of the Oxford study.
“However, it takes some more time [for the government] to fully study the safety of such use,” Tai added.
Oxford’s newly-published study, the Com-COV vaccination trial, seems to offer greater hope for the cutting-edge vaccination approach to be practiced in Macau.
According to the study, which examined the potency of a mixed vaccine schedule involving the Pfizer-BioNTech (Pfizer) and Oxford-AstraZeneca (AstraZeneca) vaccines, a mixed vaccine schedule was found to “generate a strong immune response” against coronavirus.
However, researchers stressed that the order that these vaccines are administered will give rise to different immune responses, with AstraZeneca followed by Pfizer displaying “the better immune response.”
The AstraZeneca-first, Pfizer-second approach is proven to induce “higher antibodies and T-cell responses” than the reverse order, the report stated.
More importantly, a mixed schedule of these two vaccines regardless of the order of administration was found to be more effective and induce a higher antibody response than the standard two doses of the AstraZeneca vaccine alone.
Meanwhile, having two doses of the Pfizer vaccine was found to generate the highest antibody response, and the completed doses produced the highest T cell response.
This study investigated the mix-and-match approach, with two doses administered at a four-week interval.
“Today’s data is a vital step forward, showing that a mixed schedule gives people protective immunity against Covid-19 after four weeks,” Jonathan Van-Tam, Deputy Chief Medical Officer Professor, stated in the report.
However, the most common interval for the AstraZeneca vaccine is eight to 12 weeks. A longer interval such as this creates a better immune response, according to Matthew Snape, Associate Professor in Paediatrics and Vaccinology at the University of Oxford and Chief Investigator of the study.
The study for the 12-week dose interval is underway, with results to be announced soon.
“The results for the 12-week interval, which are yet to come, will have an instrumental role to play in any decisions about the future of the U.K.’s vaccination program,” Van-Tam said.
The Oxford report is considered to offer much-needed confidence to some European countries, which have offered other vaccine types as an alternative second shot to replace the AstraZeneca vaccine, after the AstraZeneca vaccine was found to be associated with rare blood clots.