Malegaon Magic study: ‘Residents did not register rapid drop in antibodies level’
At a time when Covid cases were registering a spike during the second wave – that of Delta variant – across the country in 2021, Malegaon city continued to report low numbers. Intrigued by the phenomenon, the Maharashtra University of Health Sciences (MUHS) undertook the Magic Malegaon project to find out why the deadly wave somewhat spared the city situated in Maharashtra’s Nashik district. To their bafflement, the researchers, in the preliminary analysis of a second round of survey in April-May this year, have found that unlike several other parts of the country, there has been no rapid drop in the level of antibodies against Covid among the residents of Malegaon.
“The first survey conducted in January this year indicated that the Covid-19 neutralising antibody prevalence was found to be much higher in the population (96 per cent) and this was mostly associated with younger age, gender, diet and vaccination status of the population. Now, preliminary analysis of a second survey of the same participants – around 1,670 in number — indicates that the decay in antibody titres was not rapid and continued to remain satisfactory in all, barring 80 persons,” Lt Gen (retd) Madhuri Kanitkar, Vice Chancellor of MUHS, told The Indian Express.
“Decay in antibody levels has been slower in Malegaon than rest of the country. In almost 88 per cent of individuals, the decline in antibodies was less than 20 per cent even after three months. In the third phase of the study, we will also assess whether the memory cells of the 80 persons with very low antibody levels are able to mount an antibody response if they are exposed to the virus,” the MUHS VC said. She pointed out that there were some people who were Covid negative in the first round of their survey and were found positive during the second serosurvey. “However, they do not remember ever getting the infection as they did not have symptoms. So, it would be interesting to know if a possible low-level infection circulating in the community worked as a natural booster to give them immunity. We are following up on these patients and looking at other demographic and social factors,” Kanitkar said.
Notably, Malegaon corporation area was a hotspot of infection in the first wave of the Covid pandemic in 2020, witnessing 178 deaths and 4,560 total infections, with a positivity rate of 18.5 per cent in the April-September period. In 2021, between February and mid-July 2021, there were 6,222 Covid positive cases and 120 reported deaths. During the third Omicron wave from January 1 till date, Malegaon has reported approximately 450 cases and no death.
“The spread of Covid-19 infection was low in this population of seven lakh in Malegaon in the second wave and even during the third wave now. This is despite the high vaccine-hesitancy,” Dr Sapna Thakare, Malegaon health officer, said. The health official said an approximate 60 per cent beneficiaries have got the first dose while few were fully vaccinated.
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At MUHS, researchers took up this epidemiological study to determine demographic factors influencing Covid-19 IgG antibody production among the adult population in Malegaon. Study findings of the first survey have also been accepted for publication in the Asian Journal of Medical Science. This includes data on a total of 2,454 participants who were screened for Covid-19 neutralising antibody by ELISA technique in the first survey in January this year.
Serological tests to detect the presence of IgG antibodies may provide a more reliable estimation of the prevalence of SARS-CoV-2 past infection in the population. “We collected 5 ml venous blood in a plain bulb for testing and found the prevalence of neutralising antibodies to be 93.9 per cent. Females had 95 per cent positive antibodies vis a vis males (92.34 per cent). Maximum positive antibody status was seen in the age group of 20 – 40 (55.6 per cent). Around 77.9 per cent persons who followed a mixed diet (vegetarian and non-vegetarian) had higher levels of antibodies as compared to those with a pure vegetarian diet (10.2 per cent). Around 83.2 per cent of people who were vaccinated also had higher antibody levels. The lowest level of antibody positivity was seen in persons who were underweight (8 per cent) followed by those who were obese (12.7 per cent). Also, maximum antibodies were seen in persons who had taken Vitamin C and Zinc tablets (92.1 per cent),” Dr Nirmalkumar A Rawandale, Head of Department of Medicine at Bhausaheb Hire Government Medical College Dhule, Maharashtra, and principal investigator of the project said.
Extensive studies are required to establish any association between prophylactic methods other than vaccination and Covid-19 antibody response, researchers said.