https://www.siliconvalley.com/2021/02/18/coronavirus-second-vaccine-dose-delayed-how-long-you-can-wait-may-surprise-you/

(CNN) — Some vaccine providers have been forced to cancel Covid-19 vaccine appointments due to the winter weather that has ravaged much of the US and caused delays in vaccine deliveries.

That can be worrisome for people who were set to receive their second dose of the two-dose Covid-19 vaccines, which are supposed to have a second inoculation administered three or four weeks after the first.