9 out of 10 Covid-19 patients in Karachi are asymptomatic, AKU study reveals

Updated 08 Sep 2020

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About 95 per cent of the people who tested positive for the novel coronavirus through blood tests reported no symptoms. — AFP/File
About 95 per cent of the people who tested positive for the novel coronavirus through blood tests reported no symptoms. — AFP/File

A recent study by Aga Khan University researchers has revealed that nine out of 10 Covid-19 patients in Karachi — considered by experts as one of the country's epicentres — were asymptomatic, a statement released by the institution said on Monday.

The study suggested that the reason hospitals in Pakistan did not face the same strain as hospitals in Spain and the United Kingdom was because most patients did not experience any symptoms and, therefore, did not require treatment.

It said the ratio of asymptomatic cases in Pakistan was much higher than that witnessed in developed countries.

The research was based on samples of residents from areas with both low and high transmission rates with researchers finding that 95 per cent of those who tested positive for the novel coronavirus through blood tests reported no symptoms.

"Antibody testing or seroprevalence provides a true picture of the burden of Covid-19 as they capture asymptomatic cases who represent silent carriers of the disease," said Dr Fyezah Jehan, a co-researcher.

"Understanding how, when and in what types of settings, Covid-19 spreads is critical to developing effective public health and infection prevention measures to break chains of transmission."

The research also confirmed the findings of an earlier study conducted by the government, which had concluded that 11pc of the population had contracted the disease, using results of antibody tests.

The rise in cases between April and June, in both low and high transmission areas of Karachi, was also confirmed by the Aga Khan University researchers. They found that the transmission rate in Ibrahim Hyderi, where community transmission rate was low, jumped from 0.2 to 8.7pc during April and June, when Pakistan saw its peak.

In areas like Safoora Goth, Pehlwan Goth and Faisal Cantonment, among others, where community transmission was high, the transmission rate increased drastically from 0.4pc to 15.1pc.

“The sharp increase in antibody levels in an area with low reported cases indicates that the virus continues to spread unchecked in populations where testing rates are sub-optimal,” said Dr Imran Nisar, an assistant professor at the university and co-investigator on the study.

The study revealed that children and adolescents are as likely to be infected as adults. It also dispelled the notion that men are more vulnerable to getting infected, concluding that members of both sexes are equally prone to contracting the virus.

The team has so far held two serosurveys — testing blood serum of a group to determine the prevalence of a virus or pathogen in a population — in which more than 2,000 people participated. A third survey is currently underway and a fourth is planned for later in September in order to determine the impact of easing the lockdown on Eidul Azha and Muharram processions.

Restrictions that were imposed by the government in the past few months have been retracted as Pakistan saw a drastic drop in cases.

Following an initial surge, the number of infections has plummeted in recent weeks, with Covid-19 deaths hovering in the single digits each day, while neighbouring India tallies hundreds of fatalities.