The letter from the health ministry said the measures taken should be based on local conditions, laying down the guidelines for what it called “threshold limits”.

The thresholds, the Centre said, are test positivity of 10 per cent or more in the last one week or 40 per cent occupancy on oxygen supported or ICU beds.

The states and Union Territories can take “containment measures, curbs even before thresholds are reached” the Centre said.

Besides Omicron, the Delta variant is “still present” in different parts of the country, the letter read.

Calling for “greater foresight, data analysis, dynamic decision making and strict and prompt containment action”, the letter said decision making at the State/UT and district level “must be very prompt and focused and take containment measures and restrictions even before these thresholds are reached”.

As part of test and surveillance methods, the Centre has mentioned door-to-door case searches, contact tracing of all Covid-positive persons.

Samples from cluster infections must immediately be sent to INSACOG Labs for Genome Sequencing.

The states have also been asked to “accelerate and ensure” 100 per cent vaccination coverage.

It has also been suggested that emergency funds be used to ramp up medical infrastructure, including hospital beds, ambulances, oxygen equipment and medication.

The number of Omicron cases has crossed the 200-mark in India, the Health Ministry has said. Maharashtra and Delhi have reported the highest number of cases of the new variant — 54. They are followed by Telangana (20 cases), Karnataka (19), Rajasthan (18), Kerala (15) and Gujarat (14). Of them, 77 patients have recovered or migrated, the ministry added.