Bengaluru: A study conducted by the Cardiovascular Science Institute Sri Jayadeva has found Covid-19 antibodies intact at 99% of cohorts, six months after they took both doses of covishield.
Dr.
CN Manjunath, Director, Jayadeva, said that 250 health workers were fully vaccinated last week, at 99%, covid antibodies were intact.
He said this shows a dose of booster is not needed at this time.
Hospital microbiology departments have carried out blood tests for IgG neutralization antibodies through the ELISA method at 250 health care staff in hospitals including doctors and nurses.
They all have received a second dose of Covishield in February this year.
The same staff batch was tested for antibodies in April too, and 79% have demonstrated a positive antibody response, while the remaining 21% has demonstrated a negative immune response.
When the test was repeated in September on the same cohort, the positive immune response was seen in 99% of them and only 1% of these health service workers continued to show a negative immune response.
Considering the kit used for this study, the cut off value of 30% reference is considered a positive immune response.
In the September study, 49% of cohorts reported more than 90% of the antibody level.
The highest antibody response was seen between 19 health workers suffering from a lightweight Covid-19 infection after being fully vaccinated.
Between April and September, only 10 health care workers showed a decrease in the level of antibodies, but they were still within the limit of a positive immune response, the researchers said.
Pending Immune ResponseDr Manjunath said this study had revealed the phenomenon of immune responses delayed among several vaccine recipients.
“During the antibody test in April, 21% had not shown a positive immune response.
When we repeated the test four months later, we saw most of them developed a positive antibody response.
This shows an indirect antibody response to some individuals.
They are called pending immune respondents , “Dr.
Manjunath said.
The study was pioneered by Dr.
Naveena J, Head of the Department of Microbiology, and the team included Dr.
MP Nandini and Dr K Kavitha, both assistant professors at the Institute.
Jayadeva conducted a study to explore the need for a booster vaccine dose for its staff, who worked in the Highrisk environment and hence very vulnerable to infection.
This study highlights the fact that two covishield doses at four weeks intervals are very effective.
The fact that the intact immune response after six months will have an impact on the booster dose vaccine policy.
“At six months, most people who are vaccinated do not require a booster dose.
However, we must undergo a cohort for fresh antibody tests at the end of the year,” said Dr.
Manjunath.
He said the results of the study would help improve the morale of health workers and the general population and would also encourage more people to take vaccines.