New Delhi, Nov 24 : The Union Health Ministry on Wednesday expressed concerns over the decreasing trends of Covid testing in some states. The health ministry said that the decrease in the Covid testing would undermine the actual infection spread within the community. "With the onset of winter and increased pollution in some states, prevalence of ILI/SARI and respiratory distress symptoms should be closely monitored, with tests conducted regularly for timely monitoring and clustering of cases for early hotspot identification", said the health ministry. In a letter to the states, the ministry said that in the absence of sustained levels of sufficient testing, it is very difficult to determine the true level of infection spread in a geography. With a majority of countries seeing multiple surges in the Covid cases in recent times and a few developed countries facing even fourth and fifth wave despite high levels of Covid vaccination, there is a need for continued vigil given the unpredictable and contagious nature of the disease. The ministry added further that all efforts must be implemented to preserve the gains made so far and to prevent deterioration of Covid-19 scenario across the country. "Nagaland has reported 342 average daily tests as on week ending 22nd November. This is in a stark contrast to a high of 1,250 average daily tests conducted in the week of August 23-29. It is also worrying to note that the state has recorded a positivity of 1.5 per cent in the week ending 22nd November, having stagnated over the past 4 weeks, with an abysmally low share of RT-PCR tests," said the ministry to the states. The health ministry has written letters to the states: Nagaland, Sikkim, Maharashtra, Kerala, Goa, Manipur, Meghalaya, Mizoram, J&K, Punjab, Rajasthan, West Bengal and Ladakh. The ministry has directed these states to maintain the momentum and build on the progress made so far to bring the pandemic situation under control. /IANS