COVID-19 cases spike again in India: Is this a new variant of COVID strain?

The increase in COVID-19 cases in India in the last one week, especially in states such as Maharashtra, Punjab, Kerala, Chhattisgarh and Tamil Nadu, is raising concerns whether the spurt in new cases is linked to new variants of SARS-CoV-2 or is it attributable to any super spreading event locally? 
India saw 16,738 fresh COVID-19 cases on February 24, nearly half of them from Maharashtra. It is well established that the variants of the UK, South Africa and Brazil are highly transmissible. The South Africa strain is known to reduce the efficacy of vaccines as well.
Here is an explainer on how dangerous are new variants, when have they been discovered and is there any link between them and new cases? Will these strains reduce vaccine efficacy or have