(CNN) Pharmaceutical company Merck announced Monday it is discontinuing development of its Covid-19 vaccine candidates after early studies showed immune responses were inferior to natural infection and other Covid-19 vaccines. Merck said its vaccine candidates appeared to be safe, but the company did not provide results from early trials. In June, Merck announced it had acquired the company Themis to focus on a measles vector-based coronavirus vaccine candidate. Another candidate, developed with the nonprofit International AIDS Vaccine Initiative, was based on technology used for Merck's Ebola vaccine. Demand for Covid-19 vaccines is high, especially as the more contagious variants of the virus begin to spread in some places.

Source: CNN January 25, 2021 13:18 UTC