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

23 Mar 2021

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 apart^b	No data
AZD1222 AstraZeneca, University of Oxford, SK BIO	MFDS Korea	2 doses, 4–12 weeks apart^b	No data
Covishield (ChAdOx1_nCoV-19) Serum Institute of India	DCGI	2 doses, 4–12 weeks apart^b	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.

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IPCRG COVID-19 and respiratory Q&A

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The content is drawn from the references listed above. Wording has been adapted for clarity and applicability for the primary care context. The content does not imply direction by the IPCRG nor does it form a position of the IPCRG on this subject. The content may be adapted as new evidence arises. This content is advisory; it is intended for general use and should not be regarded as applicable to a speciﬁc case.

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