WHO says Moderna COVID-19 vaccine doses can be up to six weeks apart

By Rachel Arthur

- Last updated on GMT


Related tags WHO Moderna COVID-19 vaccine

Advice published by the World Health Organization today says the two doses of the Moderna vaccine should be administered 28 days apart; but this interval can be extended up to 42 days if necessary.

The WHO’s Strategic Advisory Group of Experts (SAGE) has issued interim recommendations for the use of the Moderna mRNA-1273 vaccine against COVID-19 in people aged 18 years and older.

It states that people should be vaccinated with two doses (100 µg, 0.5 ml each) 28 days apart: and “If necessary, the interval between the doses may be extended to 42 days.”

The advice is similar to that issued for the Pfizer vaccine: which it said should be issued 21-28 days apart, or up to six weeks apart in some situations.

Additional WHO advice on the Moderna vaccines reads: “The vaccine is safe and effective in people with known medical conditions associated with increased risk of severe disease, such as hypertension, diabetes, asthma, pulmonary, liver or kidney disease, as well as chronic infections that are stable and controlled. Although further studies are required for immunocompromised persons, people in this category who are part of a group recommended for vaccination may be vaccinated after receiving information and counselling.

“The vaccine can be offered to a breastfeeding woman who is part of a group recommended for vaccination (e.g. health workers); discontinuing breastfeeding after vaccination is currently not recommended.”

Vaccination is not recommended for pregnant women unless they are considered to be at risk of high exposure (such as health workers); and it is not recommended for anyone with a history of severe allergic reaction to any component of the vaccine.

Very frail older persons with an anticipated life expectancy of less than three months should be individually assessed.

Moderna’s vaccine has yet to receive Emergency Use Listing from the WHO but has undergone review by the European Medicines Agency (EMA) and meets the WHO’s criteria for SAGE consideration.

Early studies show the vaccine appears to be effective against the strains originating in South Africa and the UK; although protection against the South African strain is diminished. As a result, Moderna announced this week that it is developing a booster shot specifically designed against the B.1.351 (South Africa) variant;​ as well as exploring the potential of a three dose regimen of its existing vaccine.

Moderna mRNA-1273 Phase 3 clinical trial

Doses were administered 28 days apart, resulting in an efficacy figure of 94.5%. The primary endpoint of the study was prevention of COVID-19 with onset at least 14 days after the second injection.

The study published in the New England Journal of Medicine​​​ notes that “results from a preliminary exploratory analysis suggest that some degree of prevention may be afforded after the first dose.”

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