The Union health ministry on Friday asked states to screen patients with flu-like symptoms and ramp up Covid-19 tests to detect any “emerging hotspots”, amid a five-fold increase in the counts of active Covid-19 cases over the past three weeks.

The call to test sufficient numbers of patients’ samples emerged at a Covid-19 preparedness review meeting called by Union health minister Mansukh Mandaviya amid concerns that the average tests per million are below average in 23 states.

India’s seven-day average of daily new lab-confirmed Covid-19 infections has increased seven-fold from 571 on March 17 to 4,188 on April 7, while the counts of active cases have increased from about 4,600 to over 28,000 over this period.

Scientists tracking genetic changes in circulating coronavirus variants say the current surge is driven by a variant called XBB.1.16, a sublineage of the omicron strain that had fuelled the country’s third Covid-19 wave but with largely mild illness.

The health ministry said the proportion of XBB.1.16 cases among samples sequenced had increased from about 21 per cent in February to 36 per cent in March. But, it said, there is no evidence of any increase in severe disease, hospitalisation or mortality.

The ministry said Delhi, Haryana, Himachal Pradesh, Karnataka, Kerala, Maharashtra and Tamil Nadu are among states reporting high numbers of Covid-19 cases. Kerala, Maharashtra and Delhi each have 10 or more districts where test positivity rates are greater than 10 per cent.

High test positivity rates — the fraction confirmed as positive among those tested — imply either a large epidemic or low levels of testing, both of which are detrimental to efforts to control an epidemic.

The health ministry on April 6 recorded 13 Covid-19 deaths nationwide, compared to four deaths on April 1, but doctors monitoring the surge have said available data suggests that almost all deaths have occurred among patients with serious underlying chronic health disorders.

Last month too, the health ministry had called on states to enhance surveillance and encourage the public, particularly vulnerable sections of the population, to adopt Covid-19 appropriate precautions.