Why WHO tag of community spread doesn’t mean much

Believe it or not, countries like Italy and Spain with more than 1.5 lakh Covid-19 cases and thousands of deaths each are not classified as being in the community transmission stage in the WHO’s daily situation reports. And yet, Syria with just 25 cases and two deaths is in this stage.

How is this possible? Starting Apr 9, the WHO reports what countries themselves define as their stage of transmission. Even Italy, Spain, France and the UK are not among the 22 countries in the “community transmission” category. All of them, and most European countries, are listed as pending classification.

Prior to that date, the transmission classification was based on WHO’s analysis of official data on cases and deaths reported by countries. The daily situation report puts out a list of countries with data on the total number of confirmed cases, new cases, total deaths and new deaths and the country’s transmission classification. Countries send detailed data on cases and deaths in a standard format to the WHO daily.

The transmission scenarios too were changed from Apr 9. These changes were based on updated guidance to member states on implementation of global surveillance for Covid-19 issued on March 20. Before Apr 9, the transmission scenarios were 1) under investigation, 2) imported cases only, 3) local transmission 4) community transmission and 5) interrupted transmission, though the details of how interruption of transmission would have been demonstrated had not been worked out.

The new transmission scenarios are 1) no cases 2) sporadic cases 3) clusters of cases and 4) community transmission. Sporadic cases seems to combine the two earlier classifications of imported cases and local transmission as it has been defined as countries or areas with “with one or more cases, imported or locally detected”. However, clusters of cases, defined as countries “experiencing cases, clustered in time, geographic location and/or by common exposures” is an additional scenario that has been introduced. The definition of community transmission has remained more or less the same.

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In the new self-reporting format, as on April 12, a majority of the 215 countries or territories reporting data to WHO, 81 classified their transmission scenario as “clusters of cases”. These included China with over 83,000 cases and over 3,300 deaths as well as India with over 8,000 cases and 273 deaths and even Maldives and Grenada with 19 and 14 cases respectively and zero deaths.

A majority of the 22 countries in the “community transmission” scenario are in the Americas, including the US, Canada, Brazil and Mexico. But it also includes South Africa with 2,028 cases and 25 deaths and Syria with just two deaths.

Almost all 60 countries classified as having “sporadic cases” have few or no deaths and hardly any has reported any new deaths. New Zealand has the highest number of cases in this group, 1,079 cases, with 1 new case and a total of four deaths. Most of Africa falls in this category. As many as 49 countries, most in Europe, are listed as “pending” along with UAE and Qatar, two hotspots for infection among the Gulf countries.

In response to TOI’s queries regarding the changes, a WHO spokesperson explained:

“As per WHO definition, community transmission occurs when countries experience a large number of cases not linkable to transmission chains with multiple clusters in different areas and face challenges with tracking all chains of spread. Although many countries are facing this situation now, every country deals with a unique epidemiology and context, with patterns that may differ across areas in the same country. For this reason, WHO believes that countries should ultimately decide on their own transmission classification and we continue to support all countries with their self-reporting process.”

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