Low immunity levels in some, despite 2 doses of AstraZeneca, Sinovac
A leading medical expert in Thailand has expressed concern that some people who’ve received both doses of either the AstraZeneca or Sinovac vaccine are showing low levels of immunity to Covid-19. According to a Nation Thailand report, Thiravat Hemachudha from the Health Science Centre of Emerging Diseases at Chulalongkorn University says that, 3 or 4 weeks after inoculation, some people show no immunity or low levels of 20 – 30%.
The report goes on to say that in order for a vaccine to be considered effective, the ability to stop a virus must be higher than 20% if immunity is to develop. It’s understood that vaccinated people will normally show an immune response that varies from low, to medium, to high, but that response must continue to increase following inoculation.
Thiravat cites the rabies vaccine as an example. Full inoculation requires injections on day zero, day 3, and day 7. Some patients will start to develop immunity around day 10 and everyone who’s vaccinated will show immunity by day 14.
Low levels of immunity, at less than 20%, are being seen in some people who were vaccinated on the same day and with the same vaccine, leading Thiravat to speculate that there may have been an issue with a particular batch. He adds that some of those showing very low levels of immunity have underlying health conditions, including diabetes, which will have an impact on their immune system.
According to the Nation Thailand report, a number of Covid-19 patients have become infected despite having 2 doses of Sinovac or 1 dose of AstraZeneca. Thiravat says that in vaccinated individuals where immunity does not increase, or where it increases to less than 68%, a third dose could be beneficial.
SOURCE: Nation Thailand
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