The World Health Organization (WHO) has concluded that the known and potential benefits of the Moderna COVID-19 vaccine mRNA-1273 outweigh the known and potential risks.
The decision follows advice from the WHO Strategic Advisory Group of Experts on Immunization (SAGE) after its extraordinary meeting on 21 January 2021.
Due to limited vaccine supplies, many countries have begun to extend intervals between the first and second dose. The new interim guidance acknowledges that there appears to be protection following one dose; however, there is insufficient information about longer-term protection beyond 28 days.
However, the WHO notes that neutralising antibody responses were modest after the first dose and increased substantially after the second dose.
The recommendation at present is that the interval between doses may be extended to 42 days as this was the longest interval for any participants in the primary efficacy analyses of the phase 3 trial.
It is recommended that priority be given initially to health workers at high risk and older people with and without comorbidities.
The WHO currently does not currently recommend vaccination of travellers, unless they are part of a high-risk group or in epidemiological settings identified in the WHO Prioritization Roadmap.