Updated: October 10, 2021 7:27:26 am
Nearly 93 per cent of 478 health workers from the urban health centres and hospitals under the jurisdiction of the Ahmedabad Municipal Corporation (AMC), who had taken either one or both doses of the Covid-19 vaccine, had antibodies as recently as in August, according to a survey.
The vaccination for health workers was conducted between January and May and all of those sampled had taken Covishield. However, six per cent of those covered in the sero survey who had taken both doses of the vaccine, showed no presence of antibodies against the virus.
The AMC initiated a study in the latter half of May to understand the efficacy of Covid-19 vaccine, Covishield, among its health workers who have received either one dose or both the doses, with an aim of tracking antibody titers every 15 days, over a period of six months.
Although until August, samples were taken once every 15 days, since September, samples are being taken once a month. According to an AMC health department official the change in sampling duration was decided upon “after it was seen that there was no material difference in seropositivity in two weeks’ time.”
With a targeted sample size of 1,009 health workers across urban health centres in seven zones and five AMC hospitals, the seventh sampling in August saw participation from 478 of the targeted health workers.
Of the 478 samples, 51 subjects, part of the seventh sampling, had taken only the first dose. Among them, 49 had developed antibodies while two did not. Among those who were fully vaccinated, antibodies were found 398 health workers, while 29 were negative for antibodies.
AMC hospitals included as part of the study include CH Nagri Eye Hospital, LG Hospital, SVP Hospital, VS Hospital and SCL Municipal General Hospital. Among those sampled, 398 subjects were such who had taken both doses of the vaccine and showed presence of antibodies against the novel coronavirus.
29 others were fully vaccinated and yet were not detected with any antibody, which an AMC health official indicated, “could be a function of elapsed time between taking the second dose and sampling.”
The official said, “Vaccination for health workers commenced on January 16. Say, someone took the first dose of vaccine in January, then took the second dose in February and March. It is possible that by August antibodies may have waned and the health worker may thus test negative for the antibody test.”
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