Inactivated vaccine followed by vector vaccine multiplies immunity boost: virologist
A vaccine cocktail of Sinovac and AstraZeneca has proved very effective, Yong Poovorawan, head of the Centre of Excellence in Clinical Virology at the Faculty of Medicine, Chulalongkorn University, reported on Saturday.
The idea to mix vaccines was considered due to limited doses for mass inoculation and the rise of the Delta strain in Thailand.
Two doses of inactivated vaccination would help immunity rise to an average level of 100 units, said Dr Yong. If two doses of the vector vaccine are given 10 weeks apart, the immune system will rise to 900 units. If the vaccines are alternated -- inactivated vaccine followed by the vector virus at 3-4 weeks -- the recipient achieved a high immunity of 700 units.
However, two doses of the inactivated vaccine followed by the virus vector vaccine -- as front-line medical personnel are now doing -- has been found to provide an average immunity boost of 10,000 units.
His team is currently conducting in-depth research into its ability to block the virus in each species, including the Delta variant.
From past data, the Delta strain evades immunity hence higher levels of immunity are needed until a vaccine that matches the epidemic strain or a second-generation vaccine is available, the virologist said.