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Saturday November 27th, 2021

AstraZeneca second shot at 12-weeks gives same antibody levels as 4-weeks: Sri Lanka study

ECONOMYNEXT – Recipients of a second AstraZeneca dose after 12-weeks showed the same levels of antibodies as those who had received it at the recommended four week interval, a study in Sri Lanka has shown.

Though Sri Lanka started giving AstraZenea from the beginning of 2020, supplies from India was disrupted with the Indian variant going viral and some 600,000 people had to wait for the second dose of the vaccine till July.

With the Japanese government donating 1,455,840 doses of the AstraZeneca vaccines, Sri Lanka started giving the second dose in August 2021.

A study done by the Allergy, Immunology and Cell Biology Unit, University of Sri Jayewardenepura, by testing the samples of late vaccine receivers, the researches stated that the antibody formation of the body has been not affected due to the delay of receiving the vaccine.

“We compared antibody and T cell responses in two cohorts with two different dosing gaps” the research team said.

“Antibodies to the SARS-CoV-2 virus were assessed in 297 individuals with a dosing gap of 12 weeks, sampled at 12 weeks post second dose (group 1) and in 77 individuals with a median dosing gap of 21.4 weeks sampled 6 weeks post second dose (group 2)”

The results showed that all individuals (100%) had SARS-CoV-2 specific total antibodies, the team said.

“There was no difference in antibody titres or positivity rates in different age groups in both groups.”

In the study, ACE2 receptor blocking antibodies (ACE2R-Abs), antibodies to the receptor binding domain (RBD) of the virus and variants of concern (VOC) and ex vivo T cell responses were also assessed.

“The ACE2R- blocking Abs (p<0.0001) and antibodies to the RBD of the VOCs were significantly higher in group 2, compared to group 01. 41.2 percent to 65.8 percent of different age groups gave a positive response by the haemagglutination assay to the RBD of the ancestral virus and VOCs in cohort 1, while 53.6 percent to 90 percent gave a positive response in cohort 2,” the researchers said.

“Both dosing schedules resulted in high levels of antibody and T cell responses post vaccination, although those with a longer dosing gap had a higher magnitude of responses, possibly as immune responses were measured 6 weeks post second dose compared to 12 weeks post second dose.”

Health authorities have vaccinated 1,479,575 people with the first dose of the AstraZeneca vaccine while 1,390,438 have received the second jab.

So far a total of 15.2 million of the population has received the first jab while 13.3 has received both first and second jab.

Authorities said a booster dose from the Pfizer BionTech vaccine will be given for Health, military, police personnel and those engaged in tourism sector after November 01,2021. (Colombo/ Oct 28/2021)

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