What evidence is available to support the recommended dosing intervals for the current SARS-CoV-2 vaccines?

23 Mar 2021
Respiratory conditions
  • COVID-19
Type of resource
IPCRG COVID-19 and respiratory Q&A

What the research says:

There are currently no systematic data to determine optimal dosing regimens for SARS-CoV-2 vaccines. Manufacturer-recommended dosing intervals for evaluation in clinical trials of current SARS-CoV-2 vaccines were selected based on expert opinion and informed by experience with other vaccines. Regulatory agencies base their marketing approval on the dosing intervals evaluated in the clinical trials conducted by the manufacturers. Clinical trials of current SARS-CoV-2 vaccines did not compare the effectiveness of the recommended (3–4 weeks) and extended dosing intervals (2–3 months). Some evidence is available for the Oxford-AstraZeneca vaccine in a relatively small number of individuals that a dosing interval of 2–3 months offered numerically higher efficacy than among those who received their second dose within 6 weeks (Voysey et al 2020).

Status of SARS-CoV-2 Vaccines within WHO EUL/PQ evaluation process (17 March 2021)a Last updated: 23 March 2021

Name of vaccine

Manufacturer
Regulatory Agency Manufacturers recommended dosing schedule Duration of immunity

BNT162b/COMIRNATY (INN tozinameran)

Pfizer, Biontech
EMA 2 doses, 21 days apart No data

AZD1222

AstraZeneca, University of Oxford
Core – EMA Non-COVAX 2 doses, 4–12 weeks apartb No data

AZD1222

AstraZeneca, University of Oxford, SK BIO
MFDS Korea 2 doses, 4–12 weeks apartb No data

Covishield (ChAdOx1_nCoV-19)

Serum Institute of India
DCGI 2 doses, 4–12 weeks apartb No data

SARS-CoV-2 Vaccine (Vero Cell), Inactivated

Sinopharm/BBIBP
NMPA 2 doses
(interval not yet specified; trials ongoing)
No data

SARS-CoV-2 Vaccine (Vero Cell), Inactivated

Sinovac
NMPA 2 doses
(interval not yet specified; trials ongoing)
No data

mRNA-1273

moderna
EMA 2 doses, 28–42 days apart No data

Ad26.COV2.S

Janssen, Johnson&Johnson
EMA Single dose No data

Sputnik V

The Gamaleya National Center
Russian NRA 2 doses, 21 days apart No data

Convidicea (Ad5-nCoV)

CanSinoBio
NMPA Single dose No data

[Name not available]

Novavax
EMA 2 doses
(interval not yet specified; trials ongoing)
No data

EpiVacCorona

Vector State Research Centre of Virology and Biotechnology
Russian NRA 2 doses, 21–28 days apart No data

Recombinant Novel Coronavirus Vaccine (CHO Cell)

Zhifei Longcom, China
NMPA Under evaluation No data

SARS-CoV-2 Vaccine, Inactivated (Vero Cell)

IMBCAMS, China
NMPA 2 doses (interval not yet specified; trials ongoing) No data

Inactivated SARS-CoV-2 Vaccine (Vero Cell)

Sinopharm/WIBP
NMPA 2 doses, 21 days apart No data

DCGI, Drugs Controlled General of India; EMA, European Medicines Agency; EUL/PQ, Emergency Use Listing/Prequalification; MFDS, Ministry of Food and Drug Safety; NMPA, National Medical Products Administration

aList of vaccines obtained from: World Health Organization. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/covid-19-vaccines. Accessed March 2021.

bWHO recommends an interval of 8–12 weeks; additional dosing regimens under evaluation.

What this means for your clinical practice:

  • SARS-CoV2 vaccination should be delivered in line with National guidance on dosing schedule.
  • In exceptional circumstances, such as in the case of someone having a first inoculation in one country and then moving to another country, the recommendations summarised in the table above may be referred to.