TechNet has recently released a page that gathers major technical guidance documents from WHO on maintaining immunization services during the Covid-19 pandemic: https://www.technet-21.org/en/topics/covid-19
Currently, you'll find global guidance as well as guidance from WHO regions. In addition, the page offers a list of the excellent OpenWHO Covid-19 learning resources.
We'll update this page as often as possible. Please finally note that it doesn't intend to replace the WHO website that also provides a full list of country and technical guidance on Covid-19.
Should you feel there's an important document that should be added to that list, don't hesitate to contact me to let us know.