The Moderna COVID-19 (mRNA-1273) vaccine: what you need to know

18 August 2022

Updated 18 August 2022, to adhere to the latest SAGE recommendations.

The WHO Strategic Advisory Group of Experts on Immunization (SAGE) has issued updated interim recommendations for the use of the Moderna COVID-19 (mRNA-1273) vaccine against COVID-19. This article provides a summary of those interim recommendations; you may access the full guidance document here.

Here is what you need to know.

Who can be vaccinated?

The vaccine is safe and effective for all individuals aged 6 months and above. In line with the WHO Prioritization Roadmap  and the WHO Values Framework, older adults, health workers and immunocompromised persons should be prioritised.

The Moderna vaccine can be offered to people who have had COVID-19 in the past. But individuals may choose to delay vaccination for 3 months following the infection.

Should pregnant and breastfeeding women be vaccinated?

Given the adverse consequences of COVID-19 during pregnancy and the increasing data supporting a favorable safety profile of mRNA-1273 in pregnancy, WHO recommends the use of mRNA-1273 in pregnant individuals. WHO does not recommend pregnancy testing prior to vaccination. WHO does not recommend delaying pregnancy or terminating pregnancy because of vaccination.

Vaccine effectiveness is expected to be similar in breastfeeding women as in other adults. WHO recommends the use of the vaccine in breastfeeding women as in other adults. In addition, vaccine-elicited antibodies have been found in breast milk following vaccination of breastfeeding women, suggesting possible neonatal as well as maternal protection. WHO does not recommend discontinuing breastfeeding because of vaccination.

Who should not take the vaccine?

Individuals with a history of severe allergic reaction to any component of the vaccine should not take this or any other mRNA vaccine.

Individuals who developed myocarditis or pericarditis following the first dose of mRNA-1273 vaccine should not receive additional doses of any COVID vaccine unless with the recommendation of their doctor or a healthcare professional. 

Can children and adolescents take the vaccine?

This vaccine is authorized for use for those aged 6 months and above, with an adjustment in the recommended dosage in those aged 6 months – 4 years, and those aged 5-11 years.

WHO recommends that countries should consider using the vaccine in children aged 6 months to 17 years only when high vaccine coverage with 2 doses has been achieved in the high priority groups as identified in the WHO Prioritization Roadmap. 

Children and adolescents aged 6 months to 17 years of age with comorbidities that put them at significantly higher risk of serious COVID-19 disease, should be offered vaccination, alongside other high-risk groups.

Studies on the safety and efficacy of the vaccine in children aged below 12 are still ongoing.

In accordance with the WHO Prioritization Roadmap, the priority remains to prevent deaths by achieving high vaccine coverage (primary series and boosters) in the highest and high priority-use groups. In general, children are at lower risk of COVID-19. That is why WHO recommends that countries prioritize vaccinating people who have higher risk first.

Is it safe?

On 30 April 2021, WHO listed the Moderna vaccine for emergency use. WHO’s Emergency Use Listing (EUL) assesses the quality, safety and efficacy of COVID-19 vaccines and is a prerequisite for COVAX Facility vaccine supply.

The Global Advisory Committee on Vaccine Safety, a group of experts that provides independent and authoritative guidance to the WHO on the topic of safe vaccine use, receives and assesses reports of suspected safety events of potentially international impact. In October 2021, the GACVS COVID-19 subcommittee concluded that the mRNA COVID-19 vaccines have clear benefits in all age groups in reducing hospitalizations and deaths due to COVID-19.

A very rare serious adverse event is myocarditis, which is mainly observed in young males aged 18-35 after the second dose. These myocarditis cases typically occurred within a few days after vaccination, are generally mild, respond to conservative treatment, and are less severe with better outcomes than classical myocarditis or COVID-19 related myocarditis.

How efficacious is the vaccine?

The Moderna vaccine after two doses and a first booster dose has been shown to have very high effectiveness against severe disease, hospitalizations and death, and modest effectiveness against symptomatic illness.

What’s the recommended dosage?

For adults aged 17 and above, SAGE recommends the use of the Moderna mRNA-1273 vaccine at a schedule of two doses (100 µg, 0.5 ml each) 8 weeks apart.

For adolescents aged 12 to 17 years, SAGE recommends 2 doses (100 µg, 0.5 ml each), given intramuscularly, 4 weeks apart.

For children aged 6 to 11 years, SAGE recommends 2 doses (50µg in 0.25 ml each), 4 weeks apart.

For children aged 6 months to 5 years, SAGE recommends 2 doses (25 µg [0.25 ml each), 4 weeks apart.

WHO recommends that the second dose should be administered 4–8 weeks after the first dose; an interval of 8 weeks between doses is preferred as this interval is associated with higher vaccine effectiveness and lower risk of myocarditis.

Compliance with the full schedule is recommended and the same product can be used for both doses.

SAGE recommends that severe and moderately immunocompromised persons should be offered an additional dose of vaccine. This is due to the fact that this group is less likely to respond adequately to vaccination following a standard primary vaccination series and are at higher risk of severe COVID-19 disease. 

Is a booster dose recommended for this vaccine?

The first booster dose is recommended for the highest priority-use groups (e.g. older adults, persons with moderate to severe immunocompromising conditions, and health workers), 4-6 months after the completion of the primary series. If more than 6 months have elapsed since completion of the primary series, the booster dose should be given at the earliest opportunity.

WHO recommends countries should consider a second booster dose 4-6 months after the first booster dose for the highest priority groups.

For persons aged 12 and above, WHO recommends the dosage of the booster dose is half the dose used in the primary vaccination series (50 µg at 0.25 ml). The benefits of booster vaccination are recognized following increasing evidence of waning vaccine effectiveness against mild and asymptomatic SARS-CoV-2 infection over time.

There is currently no recommendation for either first or second booster doses in children under the age of 12, except for children with immunocompromising conditions.

Can this vaccine be ‘mixed and matched’ with other vaccines?

SAGE accepts two heterologous doses of WHO EUL COVID-19 vaccines as a complete primary series.

For countries considering heterologous schedules, (e.g. using different COVID-19 vaccine platforms), WHO has made the following recommendations:

  • Either of the WHO EUL COVID-19 vectored vaccine (Janssen or AstraZeneca Vaxzervia/COVISHIELD) can be used as a second dose following a first dose of the Moderna vaccine, dependant on product availability.
  • The Moderna vaccine can also be used as a second dose following any of the WHO EUL COVID-19 inactivated vaccines (Sinopharm, Sinovac or Bharat) or any of the vectored vaccines (Janssen or AstraZeneca Vaxzervia/COVISHIELD) 
  • The Moderna vaccine can also be used as a booster dose following any of the COVID-19 vaccines with WHO EUL.

Does it prevent infection and transmission?

There is only modest impact on preventing mild infections and transmission, particularly in the context of Omicron. 

Immunity persists for several months, but the full duration is not yet known. A booster dose restores vaccine effectiveness against Omicron, in particular against severe disease.

In the meantime, we must maintain public health measures that work: masking, physical distancing, handwashing, respiratory and cough hygiene, avoiding crowds, and ensuring good ventilation.

Does it work against new variants?

The vaccine remains effective against virus variants, though for the Omicron variant, vaccine effectiveness against severe and mild disease after two doses is lower compared to Delta, and waning is more rapid. Therefore, a third dose (first booster) is recommended for all adults, and a second booster for the highest priority-use groups.

How does this vaccine compare to other COVID-19 vaccines already in use?

It is impossible to compare vaccines head-to-head due to the different approaches taken in designing the respective studies, but overall, all of the vaccines that have achieved WHO Emergency Use Listing are highly effective in preventing severe disease and hospitalization due to COVID-19.

 


This webpage was updated on 18 August 2022 to reflect the latest guidance.

This webpage was updated on 10 June 2022 to ensure consistency of formatting.

This webpage was updated on 23 February 2022 to update the latest guidance.

This webpage was updated on 5 January 2022 to update the latest guidance and ensure consistency of information and formatting.

This article was revised on 29 January 2021 to include a section dedicated to pregnant women, but the recommendations remain the same. 

There will be no further updates to this page. For more information on Covid-19 vaccines