Describing COVID-19 as a "once-in-a-lifetime" pandemic that has brought tragedy and sufferings at doorsteps of many and caused huge economic impact, Prime Minister Narendra Modi said on Wednesday that the planet will not be the same after this and the events in future will be remembered as either pre or post-Covid.

Delivering the keynote address on the occasion of "Vesak Global Celebrations" on Buddha Purnima, Modi noted that the pandemic has impacted every nation but added that there have been many noteworthy developments which strengthen our strategy to fight it.

"Most importantly, we have the vaccine which is absolutely important to save lives and defeat the pandemic," he said, asserting that the emergence of jabs within a year of the COVID-19 outbreak shows the power of human determination and tenacity.

India is proud of its scientists for developing vaccines, Modi said, and also saluted healthcare and frontline workers for risking their lives to save others.

Offering condolences to those who have suffered and lost near and dear ones in the pandemic, the prime minister said he grieved with them.

In COVID-19, the humanity has faced its worst crisis in decades and has not seen a pandemic like this for a century, he said.

On the occasion, Modi also highlighted the issues of climate change and terrorism, saying one must not lose sight of the other challenges faced by humanity while fighting the pandemic.

With the prime ministers of Nepal and Sri Lanka and the secretary general of International Buddhist Confederation in attendance at the virtual event, Modi gave a call for all those who believe in humanity to come together and defeat terrorism and radicalisation.

The life of Gautama Buddha was about peace, harmony and co-existence, he noted, adding that there are still forces whose existence depends on spreading hate, terror and mindless violence.

Such forces do not believe in liberal democratic principles, he added, according to a statement.

Referring to the issue of climate change, Modi said the reckless lifestyle of the present generation is threatening future generations, and said our planet should not remain wounded.

Buddha's emphasis was on a way of life where respect for mother mature is paramount, he said, highlighting that India is among the few large economies to be on track to achieve their Paris targets.

For India, sustainable living is not only about right words but also about right actions, he said.

Modi said Lord Buddha devoted his life to removing human suffering and noted that in the last one year, several individuals and organisations rose to the occasion and did everything possible to reduce human suffering during the pandemic.

Generous contributions of equipment and materials were made by Buddhist organisations and followers of Lord Buddha from around the world, he said, adding these actions are in line with his teachings of "blessings, compassion and welfare of all".