Congress leader Rahul Gandhi on Friday asked the government why "large-scale testing is not being done" to check and prevent the spread of the Delta plus variant of coronavirus and how effective are the vaccines against it.

Many experts feel that the Delta plus variant, which has been declared as a ''variant of concern'' by the Union health ministry, may trigger a third wave of COVID-19 infections in the country.

"Questions to the Modi government on Delta plus variant: Why is testing not being done on a large scale to check and prevent it? How effective are the vaccines against it and when will complete information be available? What is the plan to control it in the third wave of the virus," he posed in a tweet in Hindi.

India was hit severely by a brutal second wave of the COVID-19 pandemic in April and May, claiming a massive number of lives daily, with a shortage in oxygen supply at various hospitals adding to the woes.

However, the number of cases have shown a downward trend and the positivity rate too has been shrinking in the last several days. From a daily case count of over 4 lakh, the number of new COVID-19 cases has been hovering around 50,000 in the last couple of days.