Update 12 October: The Director-General of the WHO spoke against the idea of letting herd immunity to COVID-19 to develop naturally by letting people in lower risk groups be exposed and infected. He pointed out that this has never been used as a public health response to a disease outbreak, and that there is not enough data to even know whether people are immune to the disease after having it. Dr. Tedros said health officials typically aim to achieve herd immunity by vaccination. "Herd immunity is achieved by protecting people from a virus, not by exposing them to it." He added that "allowing a dangerous virus that we don’t fully understand to run free is simply unethical."
Posted 11 October: The World Health Organization’s special envoy on COVID-19 Dr. David Nabarro in an interview stated lockdowns are not helpful as the primary means to control COVID-19. He advocated a middle path which means holding the virus at bay whilst keeping economy and social life going. It would require "high level of organisation by governments and remarkable degree of engagement of people" with robust infectious disease control services or public health. He emphasised on combining of several measures such as "physical distancing , face protection, hygiene, isolating the ill and protecting the vulnerable" as an effective method. See the complete interview here on YouTube.
This resonates with the "Great Barrington Declaration", a petition endorsed by numerous public health scientists and epidemiologists urging policymakers to take a focused approach called 'Focused Protection' instead of lockdown policies. They advocate promoting herd immunity while taking measure to protect the vulnerable groups.