•The study that saw samples analysed from 41 individuals that had received three doses of AZ
•The study was performed independently by investigators at the University of Oxford
Image: ANDREW KASUKU
A study by the Oxford University has found that a third AstraZeneca booster dose works effectively against the new Omicron variant.
Omicron is now the predominant strain in the country overtaking Delta after genome sequencing conducted by local experts found it was accounting for 100 per cent of the samples tested.
As the variant continues to spread globally, the study that saw samples analysed from 41 individuals that had received three doses of AZ and 20 individuals that had received three doses of Pfizer vaccine found AZ significantly boosted antibody levels against Omicron.
The experts found that neutralising antibody levels against Omicron following a third dose boost of Covid-19 Vaccine AstraZeneca were broadly similar to levels achieved after two doses against the Delta variant.
“It is very encouraging to see that current vaccines have the potential to protect against Omicron following a third dose booster,” Professor of Medicine at University of Oxford and one of the study investigators John Bell said.
“These results support the use of third dose boosters as part of national vaccine strategies, especially to limit the spread of variants of concern, including Omicron,” he added.
According to the study, the levels seen after the third dose booster were higher than the neutralising antibodies found in individuals who had been previously infected with and recovered naturally from Alpha, Beta, Delta variants and original strain.
Sera obtained from individuals one month after receiving the third dose booster vaccination neutralised the Omicron variant to levels that were broadly similar to those observed one month after the second dose against the Delta variant.
The study analysed blood samples taken from individuals infected with Covid-19; those who had been vaccinated with a two-dose schedule and a third dose booster; and those who had reported previous infection from other Covid-19 variants of concern.
The study was performed independently by investigators at the University of Oxford and the findings were posted online on the bioRxiv preprint server.
“Covid-19 Vaccine AstraZeneca plays an important role in vaccination programmes around the world and this data give us confidence that the vaccine should be given as a third dose booster,” the Executive Vice President, BioPharmaceuticals R&D, AstraZeneca Mene Pangalos said.
This comes barely a week after the Health Ministry opened up issuance of booster doses to individuals who are already fully vaccinated.
The guidelines released last Saturday will now see Kenyans who had been fully vaccinated receive an additional dose of Moderna, AstraZeneca or Pfizer vaccine six months after completion of the primary series.
The Ag Health DG Dr Patrick Amoth said the new directives were arrived at following advice from the Kenya National Immunisation Technical Advisory Group (KENITAG).
The advisory committee has also okayed the mix and matching of vaccines after the World Health Organisation last week issued interim recommendations on the same.
“The population that has been fully vaccinated should be offered an additional dose of either AZ, Moderna or Pfizer vaccines six months after the completion of the primary series. The same or different vaccine can be used for the additional dose,” Amoth said.
The guidelines have been sent to the Council of Governors and the county directors for health for implementation.
“Individuals who have received the first dose of Moderna cab receive AZ as the second, 28 days after the Mordena shot was administered,” Amoth aid.
Simialrly, individuals who report serious adverse reactions after receiving a vaccine can be switched to a different type for completion of their vaccination schedule.
The DG has noted that for instance, if a serious adverse event occurs after Pfizer of Moderna administration, AZ should be provided 28 days after the initial dose.
After the serious adverse events occur after administration of the AZ vaccine, Pfizer or Moderna vaccines should be provided as he second shot eight weeks after the initial shot.