Delhi is on track to achieving herd immunity, sero-survey indicates
What's the story
More than 50% of those surveyed in Delhi have developed antibodies against COVID-19, suggested the fifth sero-survey results. While this doesn't exactly confirm that half of Delhi has achieved herd immunity against the SARS-CoV-2 virus, the latest serological survey comprises a sizeable sample size of 28,840 individuals.
The findings indicate that the general population of Delhi is close to achieving herd immunity against COVID-19.
On track
Figures reveal large number of asymptomatic infections
The latest Delhi survey started on January 11 and detected the highest ever seroprevalence of antibodies against the virus. The number rose from 25.5% in September to over 50% now.
Speaking to Indian Express, Dr. Shobha Broor, the Head of Microbiology at AIIMS, stated that the survey reveals a large number of asymptomatic infections in Delhi, which is on track to achieving herd immunity.
Immunity
Delhi's seroprevalence is significantly higher than the national average
In one unnamed Delhi district, the prevalence of antibodies was as high as 58%. This confirms the asymptomatic infection theory since the actual number of reported cases has been steadily declining.
Pune is the only other city that has recorded more than 50% seroprevalence of COVID-19 antibodies. In most other parts of the country, the numbers average between 30% and 40%.
Herd immunity
Individuals with antibodies will reach 70%: AIIMS official
Dr. Broor said that the number of individuals with antibodies may reach 70% in the next round of survey going by the current growth rate. This generally has a negative effect on the rise of new infections, so COVID-19 cases should decline as a consequence.
However, antibodies against the virus are temporary, so that doesn't preclude individuals from vaccinating themselves against the virus.
Invaluable tool
The role of serological surveys in tackling the pandemic
The Indian Government's serological surveys are a potent tool in determining the course and severity of the deadly pandemic.
Analysis of large enough sample sizes, such as this one, provides invaluable insights to scientists and medical professionals and helps them devise a viable strategy to contain the spread of the virus.
Studies like this are vital to formulating an effective vaccination plan.