Longer delays up to 45 weeks before the second dose of Oxford-Astrazeneca vaccine, produced as a covishield in India, leads to an increase in immune response, a researcher University of Oxford study has found.
In the pre-packs of research, the researchers also concluded that the third dose of vaccines would substantially increase the immune response.
Like many countries, including India, this research has chosen to delay the second dose. It is given the shortcomings in the supply of covishield vaccines.
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In May, the Modi government said that the second dose of the covishield vaccine after a 12-16 week gap since the first dose contradicts the previously set 6-8 weeks. This causes uncertainty about how effective the vaccine is in protecting against the virus.
“The lack of vaccines has produced several people who received the first dose of ChadoX1 NCOV-19 without receiving the second dose in the recommended 4-12 week period”. The researchers stated about the implications of thier study and findings. “We do report that the increasing the interval as far as 45 weeks produces a decrease in antibody titers after the second dose, offers greater flexibility in vaccination schedules.”
The researchers studied the second delayed dose-effect through phase 1/2 (COV001) and phase 2/3 (COV002) from the ongoing clinical trial of the Oxford-Astrazeneca vaccine.
In the trial, the participants, who were in the 18-55-year-old group, were given. The Oxford-Astrazeneca vaccine (ChadoX1 NCOV-19) or the meningococcal vaccine as a control.
“As a cohort of comparisons for those who have a long interval between the first and second doses in COV001. A new subset of the participants from COV001 and COV002. Who have received two doses of ChadoX1 NCOV-19. With varied boost prime intervals selected to be included in the analysis,” this study noted.
The initial Phase 1 group data in the COV001 was also analyzed “to observe the persistence of immune response after a single dose”.
REACTIVIZENT DATA 321 participants and immunogenicity data 261 participants, available from two experiments, used in this study. At the same time, reactogenicity refers to the person’s reaction to vaccines. Immunogenicity refers to vaccine capabilities (or foreign substances) to provoke the immune response.
The participants have been given a second dose on the gap of 8-12 weeks, 15-25 weeks or 44-45 weeks.
Then in March this year, the researchers added substudies to phase 1/2, and 90 participants who had been given two doses and 40 control participants were recruited to test the third dose effect.
The antibody response was examined at 75 participants, while “a surge in specific cellular immune response” was analyzed at 15.
The level of antibodies remains increased above the basic level for a year after the first dose administration. The rate peaked at 28 days, halved to 180 days, and reached 0.30 peak levels on day 320. The second dose caused an increase in antibody response 4 to 18 times in one month from the dose administration.
“Furthermore, the extension of the dose interval (up to 45 weeks) between the first and second doses increases the immune response to the second dose, when compared to shorter dose intervals,” said this study.
This is important. The researchers found that the antibody titers were in 923 on those who had given the second dose. In intervals of 8-12 weeks, 1,860 to those who remember Jab.
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In intervals of 15-25 weeks and 3,738 on those who gave the second dose. In 44-45 weeks intervals.