Coronavirus | Sero-surveys show COVID-19 peak far away, say experts


Half the people, or 57%, tested in the slums in Mumbai had been exposed to and developed antibodies against the SARS-CoV-2 virus as compared with only 16% of those tested in residential societies, according to a survey conducted by the Brihanmumbai Municipal Corporation in three wards of Mumbai.

Results from Delhi’s seroprevalence study earlier this month found that nearly a quarter of the 21,000-odd samples tested suggested exposure to the virus, and some of the densest districts had over 20% prevalence.

Also read | India reports over 1 million COVID-19 recoveries

These studies, said an expert, suggested that a peak in infections was nowhere on the horizon.

“Testing strategies differ in the two cities, though they lead the tables in confirmed cases. The positive is that casualty rates from the disease are lower than initially expected. However, it is also evident that the lockdown or the measures to arrest the spread of the disease have largely failed,” said a government epidemiologist involved in the surveys, who did not want to be identified.

‘Still susceptible’

Conducting seroprevalence surveys in different cities of India is a positive thing, said another expert. Dr. Giridhar Babu, Professor and head, Lifecourse Epidemiology, Public Health Foundation of India, told The Hindu: “We need more rounds in future to understand the nature and extent of the transmission. It is too early to provide definitive inferences based on the available seroprevalence estimates. Except for the slum settings in Mumbai, early indicators suggest that three cities [non-slum settings of Mumbai, Ahmedabad and Delhi] have seroprevalence of around 20%. Most parts of these three metros might have had a peak in the past but still, a vast majority of people in urban areas are susceptible.” Continuing use of masks is important as 80% of the people in India are still susceptible to COVID-19.”

In the Mumbai survey, 6,936 people — 61% of them slum-dwellers — were sampled.

The Hindu Explains | What are the implications of the Delhi sero-survey findings?

The study also found a high proportion of asymptomatic COVID-19 infections in the city. Civic authorities claimed the sero surveillance result indicates that “asymptomatic infections are likely to be a high proportion of all infections”.

“Although prevalence in women was marginally higher than men, age-wise prevalence in the population was comparable in these wards,” the BMC said in a statement.

The high exposure in slums indicates that fatality rate in Mumbai may be “as low as 0.05-0.10%”, instead of the existing 5.5%, said a release accompanying the survey.

Also read | Sero surveillance survey in Kerala yields ‘unexpected’ results

Delhi has adopted a policy of widely deploying antigen tests, a quicker alternative to the RT-PCR (reverse transcription polymerase chain reaction) test, but the results are potentially missing nearly half of those who could be carrying the virus. The prescribed procedure is to retest those with symptoms but only a small fraction in Delhi, less than 0.5%, were retested, as The Hindu has previously reported. This strategy also misses out asymptomatics who may be potential carriers of the infection.

You have reached your limit for free articles this month.

To get full access, please subscribe.

Already have an account ? Sign in

Show Less Plan

Subscription Benefits Include

Today’s Paper

Find mobile-friendly version of articles from the day’s newspaper in one easy-to-read list.

Faster pages

Move smoothly between articles as our pages load instantly.

Unlimited Access

Enjoy reading as many articles as you wish without any limitations.

Dashboard

A one-stop-shop for seeing the latest updates, and managing your preferences.

Personalised recommendations

A select list of articles that match your interests and tastes.

Briefing

We brief you on the latest and most important developments, three times a day.

*Our Digital Subscription plans do not currently include the e-paper ,crossword, iPhone, iPad mobile applications and print. Our plans enhance your reading experience.



Source link

Leave a Reply

Your email address will not be published. Required fields are marked *