Ahmedabad Municipal Corporation studying Covishield efficacy among its health workers: official

According to AMC officials, health workers across civic body’s urban health centres and hospitals will be tracked for antibody titers every 15 days, over six months. It may be further extended depending on the efficacy data collected.

“It will soon be registered as a trial. We have already taken the first data point in the last week of May (of the total estimated 12 data points) of approximately 1,000 health workers, after getting approval from our ethics committee. We selected health workers as it is easy to track them periodically and they are the most exposed to the risk of getting Covid,” said an AMC official on condition of anonymity.

The civic body has not been tracking breakthrough infections — those infected among the general population after getting vaccinated — as “it is practically not possible”, another AMC official said.

“We see cases where people test positive for Covid-19 after taking the vaccine. The incubation period of the virus is seven days, so it could be that they took the vaccine during this period. Then it would not qualify as a breakthrough infection,” the official added.

The AMC is also conducting another round of sero survey which is the fifth, which is separate from the vaccine efficacy study, and is registered with the Clinical Trials Registry – India (CTRI). The serosurvey will look solely at the presence of Covid-19 antibodies owing to infection or due to the vaccine. According to an AMC source, the final data will also include an analysis to determine seropositivity among vaccinated general population.

On June 4, the Muljibhai Patel Urological Hospital in Kheda registered an observational, cross-sectional single arm trial to study post-vaccination Covid-19 rate among its employees with an expected sample size of 500 participants.
The study plans to look at symptomatic confirmed breakthrough infections.

Speaking to The Indian Express, principal investigator and head of urology department, Dr Ravindra Sabnis, said, “We will look at incidence and severity of infection after the vaccine. In the published data so far (globally), the incidence of symptomatic infection post-vaccination has been low but anecdotally from what we have seen, this may not be the case. Our sample is that of health workers who are quite exposed to the virus and are a vulnerable population… some of them have been serious and severe infection (post vaccine).”

“We estimate that the data collection would be completed in a week as it is a survey-based study. We will look at symptomatic, RTPCR-confirmed positive cases among our employees… and then statistically analyse the severity of infection (including hospitalisation or ICU admissions or mortality, if any),” Dr Sabnis added.

“We are contemplating a separate study where we will look at antibody titres of all our vaccinated employees,” Dr Sabnis added.