A World Health Organization (WHO) expert panel issued its first guidance on the Moderna COVID-19 vaccine, saying that it should ideally be given to people in two separate doses, 28 days apart.
In exceptional circumstances this period could be extended to 42 days, said WHO’s advisory group of experts on immunization, SAGE, amid supply shortages affecting many countries.
The development follows SAGE’s recommendations on 5 January on how the similar Pfizer Covid-19 vaccine should be used, as deaths from the new coronavirus topped 2.1 million globally. Both are so-called mRNA vaccines which trigger an immune response by teaching the body to make special proteins, as opposed to including any live or inactive weakened virus.
“Based on current evidence, SAGE recommends the administration of two doses — 100 micrograms, 0.5 milliliter each
— with an interval of 28 days between doses,” Dr. Alejandro Cravioto, SAGE Chair said. “SAGE recommends at present that, if judged necessary, due to exceptional circumstances of Covid-19 disease burden in a country, the interval between doses may be extended to 42 days.”
At a virtual press conference, the SAGE chief noted that this was the longest interval provided in clinical trials to date.
But it will be up to countries to decide how to act on these recommendations.
“It’s because of the severity of the disease, which is compromising our health systems, causing untold numbers of deaths, severe cases, long-term complications — that’s the problem here,” said Dr. Kate O’Brien, Director, Department of Immunization, Vaccines and Biologicals at WHO.
“So in order to take the limited supply that we have, and deploy that where it’s going to make the most difference to a country, we really have to be committed to prioritization based on epidemiology, based on what the science says about how we’re going to get out of this.”
Responding to questions over the potential dangers of the vaccine to pregnant women — particularly those who were health workers and who therefore ran a higher risk of becoming infected, along with others suffering from underlying illnesses — the SAGE panel noted in a statement that “WHO recommends not to use (Moderna) mRNA-1273 vaccine in pregnancy, unless the benefit of vaccinating a pregnant woman outweighs the potential vaccine risks.”
Nevertheless, some 7,000 pregnant women have already had the Moderna mRNA-1273 vaccine and this data will be reviewed as soon as possible, said Dr. Joachim Hoùmbach, Executive Secretary of SAGE.